GCSE Astronomy - Pearson Edexcel - COMPLETED Flashcards

Question

When does the Sun lie directly over the equator?

Answer 1

March 21st and September 23rd; these dates also correspond to the vernal and autumnal equinoxes

Answer 2

21st June; this is also the summer solstice

Answer 3

21st December; this is also the winter solstice

Answer 4

The Arctic and Antarctic Circles represent the most Northern (66.5 Degrees North) and Southern (66.5 Degrees South) latitudes

Answer 5

The atmosphere: 1. Provides us with oxygen to breathe 2. Absorbs harmful UV and X-radiation 3. Regulates our planet's temperature to mean 15 Degrees Celsius 4. Protects us from most meteoroid strikes

Answer 6

The drawbacks of the atmosphere are: 1. The sky is blue restricting observations to night time 2. Light is scattered by oxygen and nitrogen molecules in our air; most scattering occurs at shortest (blue) wavelengths so the sky is blue 3. Air is in the atmosphere and is consistently in turbulent motion. Different densities of air rise and fall on a variety of scales causing light to react and change direction as it passes through the different layers making the stars 'twinkle'

Answer 7

Some major problems are: 1. Skyglow (the rusty orange haze caused by lights near urban communities) 2. Local glare from things like streetlights ruin astronomer's dark adaptation

Answer 8

Iron and nickel

Answer 9

Silicon and oxygen

Answer 10

Evidence: 1. Satellites orbit the Earth 2. Ships disappear over the horizon 3. The Earth casts a curved shadow during an eclipse 4. Aircraft fly in arcs (not straight lines) 5. Images of the Earth from space

Answer 11

The line around which the Earth rotates?

Answer 12

66.5 Degrees

Answer 13

1. Ocean of Storms 2. Copernicus Crater 3. Kepler Crater 4. Sea of Crises 5. Apennine Mountains 6. Sea of Tranquillity 7. Tycho Crater

Answer 14

Lunar Maria were formed by ancient volcano eruptions which caused lava to flow into large basins. Molten lava was able to seep upwards near the edges of the Maria

Answer 15

Terrae are the lighter parts of the Moon and called the Lunar Highlands. They are composed of Feldspar, which is lighter in colour than the Maria as it has crystallised slower, and also reflects more of the Sun’s light

Answer 16

The Lunar Craters were formed from collisions with asteroids and meteorites on the surface. As the Moon has no atmosphere, there is no protection from incoming missiles

Answer 17

Nearer the edges of the Maria, the mountain ranges were thrust upwards, forming mountains

Answer 18

Lunar Valleys form in between the mountains

Answer 19

The Moon is tidally locked with the Earth

Answer 20

Lunar Libration

Answer 21

Libration Latitude

Answer 22

Libration Longitude

Answer 23

The Far side is devoid of Maria

Answer 24

The Moon’s equator is inclined to the plane of its orbit around the Earth by 1.5°; the plane of the Moon’s orbit is inclined at 5.1° to the ecliptic; this makes the Moon appear very high in the sky which is Libration in Latitude

Answer 25

Libration in Longitude occurs from the Moon's varying speed in its elliptical orbit around Earth

Answer 26

The point in the orbit of the moon or of an artificial satellite most distant from the centre of the Earth

Answer 27

The point nearest the earth’s centre in the orbit of the moon or a satellite

Answer 28

The Terminator is the line that separates light and darkness on the moon

Answer 29

Second and Third contact

Answer 30

Danjon Scale

Answer 31

The Apennine mountains are located between the Sea Of Serenity and the Sea of Rains

Answer 32

During the Moon’s orbit, the orbital speed changes due to its elliptical orbit. The Moon’s rotation remains constant. This allows the eastern and western limb to be visible during different times of the lunar month

Answer 33

The Maria have less craters in them suggesting they are younger as they aren’t old enough to have many craters from old impacts

Answer 34

There is a high contrast around the area which creates exaggerated shadows

Answer 35

The Moon’s equator is inclined to the plane of its orbit around the Earth by 1.5 Degrees

Answer 36

The plane of the Moon’s orbit is inclined at 5.1 Degrees to the ecliptic

Answer 37

Tidal locking is when a satellite's orbital period exactly matches its rotational period. An example is the Moon. Only one side of the Moon ever faces the Earth

Answer 38

1. Giant Impact Hypothesis 2. Fission Theory 3. Capture Theory 4. Co-Accretion Theory

Answer 39

The phases of the Moon occur because the Moon is always 50% illuminated and 50% in darkness. When the Moon orbits around the Earth, the angle we view the Moon from changes so we see different amounts of light and dark sides of the Moon

Answer 40

A large astronomical body (named Theia) struck Earth and the debris cooled and condensed to become the Moon

Answer 41

The Earth was spinning so quickly, a part of Earth broke off and formed the Moon

Answer 42

The Earth and Moon were formed at different places in the Solar System but the Earth captured the Moon with the Earth’s gravitational force

Answer 43

The Co-Accretion theory is the theory that the Earth and the Moon formed together at the same time out of material from a solar nebula

Answer 44

The Giant Impact Hypothesis is supported by the Moon’s lack of substances that evaporate (volatiles), the discovery of KREEP-rich rocks on Moon and its small iron core

Answer 45

When a large light source casts a shadow of a small object, it results in a dark central shadow with a surrounding lighter shadow

Answer 46

A 'Blood Moon' is when the Moon appears to turn red during a lunar eclipse

Answer 47

When the Moon is completely blocked by the Earth, no light directly reaches the Moon’s surface. The only light that reaches the surface of the Moon, are the rays that have been refracted from the Earth’s atmosphere and red rays have the longest wavelengths so refract the most and are able to be bent so much that the rays hit the Moon. Therefore, the Moon appears red

Answer 48

This is the time when the Moon first enters the Earth’s Penumbra

Answer 49

This is the time when the Moon is completely in the Umbra

Answer 50

This is the time when the Moon first starts to exit the Earth’s Umbra

Answer 51

This is the time when the Moon exits the the Earth’s Penumbra

Answer 52

Small bright spots of Sunlight before and after totality which are caused by the Sun’s rays shining through the valleys on the Moon

Answer 53

When only one of Baily’s beads is visible

Answer 54

The Moon and the Sun both roughly have angular diameters of 0.5 Degrees

Answer 55

Gravitational High Tide is when the Moon’s gravity makes the Earth’s water bulge so it is a high tide when you are facing the Moon

Answer 56

Inertial High tide is when the water that isn’t pulled by the Moon, becomes flung outwards by the spinning Earth

Answer 57

When the Earth spins away from the high tide

Answer 58

When the tides are controlled by the Moon’s gravity

Answer 59

The inverse square nature of the force causes the gravitational pull of the larger object on the smaller object’s nearer side to be greater than that of its far side. This is equivalent to two equal and opposite forces acting on the near and far sides that tend to stretch and elongate the smaller object. The smaller object also causes a similar, but weaker force on the larger object

Answer 60

The Moon exerts tidal forces onto the Earth causing tidal bulges in the oceans on the parts of the Earth facing towards and away from the Moon

Answer 61

There are two daily high and low tides

Answer 62

Tides caused by the Moon

Answer 63

Tides caused by the Sun

Answer 64

‘Low’ high tides

Answer 65

‘High’ high tides

Answer 66

Spring tides can only occur when the moon is in the full or new phase

Answer 67

The positions of the Solar and Lunar tides add up

Answer 68

Neap tides can only occur during quarter moons

Answer 69

Neap tides occur as the solar tide adds to the lunar low tide, which partially cancels it out

Answer 70

Precession

Answer 71

Precession is the change in the orientation of the rotational axis of a rotating body

Answer 72

1. The changing ‘Pole Star’ 2. The changing locations of the equinox: these are drifting westwards. For example, the First Point of Aries that is used to mark the spring equinox but this is now in Pisces 3. The misalignment of ancient monuments and temples

Answer 73

When the Moon passes directly in front of the Sun , it obscures light for observers and produces a dark shadow

Answer 74

The area during a Solar eclipse where the Sun is fully covered by the Moon

Answer 75

The area of observation where the Sun is partially covered

Answer 76

Baily’s beads are when the Sun’s rays shine through the valleys of the Moon and are visible

Answer 77

The diamond ring effect is when only one Baily bead is visible

Answer 78

When the Moon first touches the Sun

Answer 79

The Moon is just about to fully cover the Sun

Answer 80

The Moon has just finished covering the Sun

Answer 81

The Moon is just about to exits the Sun’s Umbra

Answer 82

An annular eclipse is when the Moon’s silhouette is slightly smaller than an normal eclipse and a ‘ring of fire’ occurs as the Moon is in its apogee in its elliptical orbit around Earth

Answer 83

Lunar eclipses occur when the Moon passes through the Earth’s shadow

Answer 84

During a lunar eclipse at totality, the Moon appears red in colour due to predominantly red light refracting through the Earth’s atmosphere and illuminating the Moon

Answer 85

When the Moon first enters the Earth’s Penumbra

Answer 86

The Second Umbral Contact is when the Moon is completely in the Umbra of the Earth

Answer 87

When the Moon first exits the Umbra

Answer 88

When the Moon completely exits the Penumbra

Answer 89

Eratosthenes

Answer 90

He read that at noon on the Summer Solstice, columns of temples did not cast any shadows in Syene (Tropic of Cancer). At the same time in Alexandria, the Sun’s position was about 7° (roughly one 50th of a circle) from the zenith. He knew that the distance from Syene to Alexandria was 790 km and used simple Geometry to work out that the circumference of the Earth was 50 x this. He worked this out to be 39,500 km. His reading was very accurate as it was in 5% of the actual circumference of the Earth

Answer 91

He determined: 1. A lunar eclipse was produced when the Moon passed into the Earth’s Umbra 2. The Sun was so far away that its rays were parallel when reaching the Earth 3. The Moon’s path took it through the centre of the Earth’s Umbra which has the same diameter of the Earth

Answer 92

Using his three assumptions, Aristarchus showed that: diameter of Moon . .Time interval from U1 to U2 ————————– = ————————————— diameter of Earth . . Time interval from U2 to U4 He calculated the Moon’s diameter was between 0.32 and 0.40 times of the Earth’s. The correct value is 0.27

Answer 93

The width of his thumbnail

Answer 94

Lengths of Shadows at local noon

Answer 95

The angle between the Sun and Moon at half-moon

Answer 96

Timings of Umbral Contacts during total lunar eclipse

Answer 97

He compared the apparent angular sizes of the Moon and the Sun

Answer 98

One year corresponds to one complete orbit of the Earth around the Sun

Answer 99

One sidereal day is the time it takes for the Earth to spin once on its axis: 23 h 56 min

Answer 100

The time it takes for the Earth to spin so the Sun appears in the same place in the sky: 24 h 00 min

Answer 101

The time it takes for the Moon to complete one revolution of the Earth

Answer 102

During the time it takes for the Moon to complete one orbit of the Earth, The Earth has moved through an angle of 27° in its orbit around the Sun. This is why the Moon needs an extra 2.2 days to re-align with the Sun and Earth again

Answer 103

Sundials indicate Apparent Solar Time (AST)

Answer 104

Apparent Solar Time is the apparent timing of the Sun seen by an observer. This is in reference to the actual position of the Sun in the Sky

Answer 105

Mean Solar Time (MST)

Answer 106

Mean Solar Time is the time calculated by the mean time it takes for the Sun to cross the sky each day in a consistent manner

Answer 107

Equation of Time is the difference between mean solar time and apparent solar time, which varies with the time of year. It is used to correct Mean Solar Time to the Apparent Solar Time

Answer 108

The real Sun is ‘fast’

Answer 109

The real Sun is ‘slow’

Answer 110

A shadow stick can determine at which time the Sun culminates and also the observer’s longitude

Answer 111

Equation Of Time= Apparent Solar Time-Mean Solar Time

Answer 112

An analemma is a chart showing how the EOT varies with the Sun’s declination during the course of one year

Answer 113

An analemma is likened to a ‘snowman’ with a bigger bottom than top

Answer 114

The Earth travels at different speeds in its orbit which causes the real Sun to move slower faster or slower in the sky on different dates

Answer 115

When it is close to the solstices, the real Sun is travelling faster from East to West than when close to the equinoxes when a large component of its apparent motion is northwards or southwards; the Sun therefore lags behind and leaps ahead of the Mean Sun in the East-West motion

Answer 116

EOT = AST - MST

Answer 117

Retrograde motion is when the planets occasionally appeared to travel backwards from east to west in a ‘loop-the-loop’ motion

Answer 118

Retrograde motion is the faster moving Earth overtaking the superior planet on the inside of its orbit

Answer 119

The band that contains all the orbits of the planets and the Sun. The band is at ~8° either side of the ecliptic due to the large orbital inclination of Mercury

Answer 120

An inferior planet is a planet that has an orbit that is smaller than the other planet in perspective

Answer 121

A superior planet is a planet that has an orbit that is greater than the other planet in perspective

Answer 122

Inferior conjunction is when an inferior planet is in between your planet and the Sun in perspective

Answer 123

Superior planet is when an inferior planet and your planet are on the opposite sides of the Sun

Answer 124

Greatest elongation is when an inferior planet appears furthest away from the Sun

Answer 125

Opposition is when a superior planet is opposite to the Sun. The superior planet is closest to Earth and at its brightest

Answer 126

A transit is when a planet goes in front of the Sun

Answer 127

An occultation is when a planet obscures a distant star as it goes in front of it for a few moments

Answer 128

RA = 12h 00min Dec. = 0°

Answer 129

A solar flare

Answer 130

A transit is when a planet and the Earth line up so that the planet appears to move across the Sun

Answer 131

An occultation is when one body in space obstructs our view of another. Transits and eclipses are types of occultations

Answer 132

When a superior planet is closest to the Earth and in the opposite section of the sky compared to the Sun

Answer 133

When to celestial bodies appear to have a close approach and look as if they overlap

Answer 134

Greatest elongation is when an inferior planet appears to be the furthest distance away from the Sun. It occurs when the Planet is at a 90° angle to the Earth and the Sun

Answer 135

A meteor shower occurs when the Earth passes through a meteor stream. The meteor stream consists of many small grains of dust and rock which become very hot through friction with the Earth’s atmosphere

Answer 136

Sirius and Aldebaran

Answer 137

When asterisms and constellations were first named, there was very little communication. Different cultures were relatively isolated compared with today, and so were unable to share/exchange stories, myths and legends. Different cultures were able to see different stars and identify patterns because of different geographical locations. Different cultures used different stories, myths and legends on which many of their asterisms and constellations were named

Answer 138

The Celestial Equator

Answer 139

An artificial satellite

Answer 140

An Aircraft

Answer 141

Reflection

Answer 142

Reflection

Answer 143

Reflection of sunlight

Answer 144

Radiation pressure from the Sun

Answer 145

Fluorescence / excitation of ions

Answer 146

Interaction with Solar wind

Answer 147

88 constellations

Answer 148

Asterisms are unofficial, popular patterns of bright stars that have a close likeness to their name. Examples include ‘The Plough’ in Ursa Major or Orion’s Belt

Answer 149

A group of stars that are roughly the same age and formed in the same giant molecular cloud. An example is the Pleiades

Answer 150

Pointes from constellations that point to another star or celestial object. An example is The Plough which points to Polaris and the ‘handle’ arc to Arcturus

Answer 151

Two stars that appear to have merged from our perspective

Answer 152

Declination is the projection of latitude onto the celestial sphere; it is measured in degrees (+&-signs indicate N or S)

Answer 153

Right Ascension is the East-to-West coordinate system. Right ascension is measured from the first point of Aries; it is measured in hours and minutes where 1 hr=15° and 1 min=0.25°

Answer 154

The Azimuth is a bearing from due north moving round eastwards to the point on the observer’s horizon directly under the star; it ranges from 0° to 360° back to 0° again

Answer 155

The Zenith is the point directly above the observer The Nadir is the point directly below the observer

Answer 156

Your Meridian is the great arc passing through the celestial poles, as well as the zenith and nadir of an observer’s location

Answer 157

Diurnal motion is when a star reaches its highest point (culminate) when they are due south as they cross the observer’s meridian and later set in the west

Answer 158

23hrs 56 mins

Answer 159

A sidereal day is how long it takes for the Earth to rotate in accordance with the stars

Answer 160

A Solar Day is the time it takes for the Earth to rotate around its axis so the Sun appears in the same position in the sky

Answer 161

A Solar day occurs because, during the time it takes for the Earth to rotate 360°, the Earth also moves around the Sun by 1° so it needs to rotate for a further 4 mins to align back to the same point as the Sun

Answer 162

Local Sidereal time is the time the Right Ascension of a star that lies on the observer’s meridian at a given moment in time. An example is if a star with RA= 14 h 45 mins lies on an observers meridian, the LST is 14:45

Answer 163

A star’s hour angle is the time since the celestial object was last crossing the observers meridian or the angular distance on the celestial sphere measured westward along the celestial equator from the meridian to the hour circle passing through a point

Answer 164

Hour Angle = Local Sidereal Time - Right Ascension

Answer 165

If the Hour Angle is negative, its value tells an astronomer how long it will take before the star or celestial object will be crossing their meridian

Answer 166

The NCP is the North Celestial Pole. It is the equivalent of a North Pole in the celestial sphere. Polaris is located within 0.8° of the NCP

Answer 167

The Altitude of a star measures the angle between the horizon, you, and the celestial object

Answer 168

The Celestial Equator is the hypothetical sphere which contains the stars ‘painted’ on the inside

Answer 169

The Ecliptic is an imaginary circle on the Celestial Sphere that represents the apparent path of the Sun during the year

Answer 170

Altitude of NCP (or SCP) = observer’s latitude Altitude of Polaris = observer’s latitude

Answer 171

Polar Distance is the angular distance of a star from the NCP

Answer 172

Polar Distance = 90° - Declination

Answer 173

The small circle that a star traces out during a sidereal day has a radius equal to its polar distance

Answer 174

When a celestial body passes your meridian at its highest point. The Upper Transit is when a star culminates

Answer 175

Lower transit is when a celestial body passes your meridian at its lowest point

Answer 176

Altitude = Latitude ± Polar Distance at upper and lower transits

Answer 177

Circumpolar stars are stars the remain visible at all times and do not set below the horizon

Answer 178

For a star to be circumpolar: 90° - Declination < latitude of the observer

Answer 179

Towards the left, it points to Sirius. To the right, it points to Aldebaran then the Pleiades

Answer 180

It points to the Andromeda Galaxy and Fomalhaut

Answer 181

A short, bright streak of light in the sky, lasting a few seconds

Answer 182

A fuzzy patch of light

Answer 183

A curtain or stream of of coloured light

Answer 184

The angle between the planet and the Sun is large. This means the planet is in a darker area of sky so contrast is greater

Answer 185

Elliptical Barred Spiral Spiral Lenticular Peculiar Dwarf Elliptical Quasar

Answer 186

2 stars the orbit around the mutual centre of gravity

Answer 187

2 stars that appear as one when viewed

Answer 188

Stars that change brightness

Answer 189

1. We’re restricted to view only at night 2. The atmosphere continuously rises and falls; this causes the stars to ‘twinkle’ 3. Skyglow; an orange haze cast by lights near urban places 4. ‘Glare’ from lights that ruins our dark adaption

Answer 190

The Van Allen belts are regions with intense radiation. The Inner belt consists of high energy protons. The Outer belts are high energy electrons that dip toward the poles

Answer 191

Measure the angle from your zenith to the Sun. Add the angle from your zenith to the Sun at the equator for this specific day

Answer 192

Seasonal constellations are the Constellations that can only be seen in certain times of the year as the Sun blocks us from viewing them when the Sun covers it up

Answer 193

Precession is the circular motion of the axis of something that is rotating

Answer 194

The current celestial alignments differ from the original alignments of the monuments because the Earth’s axis of rotation isn’t fixed; it precesses

Answer 195

Aristotle and Plato models suggested a geocentric system with the Earth at the centre of the Solar System

Answer 196

The Geocentric system had an inability to explain the observed retrograde motion of the planets

Answer 197

Each planet was placed on a small rotating circle (an epicycle) whose centre revolved around the Earth on another circle (the deferent)

Answer 198

Ptolemy put the Earth slightly off-centred and an imaginary point called the Equant from which the angular motion of the centre of each epicycle was uniform

Answer 199

The Heliocentric system is a model that suggested the Sun was at the centre of the solar system

Answer 200

Archistarchus of Samos argued for a Heliocentric system in c.270 BCE based on his calculations that the Sun was much larger than the Earth However, the theory was only recognized as a real hypothesis from Nicholas Copernicus who applied mathematical modelling

Answer 201

Galileo used the first telescope to observe the sky. He provided evidence for the Heliocentric theory: 1. The apparent size of the Planet Venus changed and showed phases 2. Four Moons that orbited Jupiter

Answer 202

The first law of planetary motion states that planets move in elliptical orbits around the Sun, with the Sun at one focus of ellipse (the other is empty). The points in the orbit at which is closest and furthest from the Sun are called the Perihelion and aphelion

Answer 203

Kepler’s second law states that an imaginary line from the Sun to a planet sweeps out equal area in equal intervals in time

Answer 204

Kepler’s third law states that the square of the orbital period (T) of a planet is proportional to the cube of its mean distance (r) from the Sun

Answer 205

T² α r³ or t² . . . . . . . . — = a constant . . . . . . . . r³

Answer 206

Newton’s law of Gravitation states that every body in the Universe attracts every other body with a force that is directly proportional to the product of their masses and inversely proportional to the square of their distance apart

Answer 207

The inverse square law states that the intensity of gravitational force is inversely proportional to the square of the distance from the source

Answer 208

The closest point in a satellite’s orbit of the Earth (it is at its fastest here)

Answer 209

The furthest point in a satellite’s orbit of the Earth (it is at its slowest here)

Answer 210

The closest point in an astronomical bodies’ orbit of the Sun (it is at its quickest here)

Answer 211

The furthest point in an astronomical bodies’ orbit of the Sun (it is at its slowest here)

Answer 212

F α 1 . . --- . . d² F = force d = distance

Answer 213

The mean thickness of the Lunar crust is 50-60 km, which is 3 times that of the Earth’s

Answer 214

The thickness in the lunar highlands on the far side can be as large as 160 km whereas, the Near side has lunar maria which is lower land

Answer 215

The radius of the Moon’s core is less than 25% of the Moon’s radius. In comparison, the Earth’s core extends to more than 50% of its radius

Answer 216

The Moon’s core is offset from the centre by about 2 km

Answer 217

The Luna 3 of Russia took the first picture of the Moon’s far side

Answer 218

The Apollo missions were a series of US-planned missions which aimed at sending the first man on the Moon

Answer 219

1. Giant Impact Hypothesis 2. Fission Theory 3. Capture Theory 4. Co-accretion Theory

Answer 220

The Giant Impact Hypothesis suggests that a large astronomical body - astronomers name Theia - stuck the Earth. Theia was vaporised and the debris cooled and condensed to form the Moon. This also suggests why the Earth is at a tilt of 23.5°. It also is supported by the fact the Moon has little volatiles and its small iron core

Answer 221

The Earth was spinning so rapidly part of it spun off and formed the Moon

Answer 222

The Capture Theory suggests that the Earth and the Moon were formed in different places in the Solar System, but the Earth caught captured the Moon with its gravitational force

Answer 223

The Co-Accretion theory suggests the Earth and the Moon formed at the same time out of material from the Solar Nebula

Answer 224

A retro-reflector A seismometer A solar wind particle collector

Answer 225

It has a thicker crust It contains more craters Almost devoid maria

Answer 226

Pinhole projection H-alpha filter Telescopic projection

Answer 227

Sunspots are cooler areas of the Photosphere where the Sun’s magnetic field rises from below the Sun’s surface and the magnetic regions poke through. They are darker in colour as they are expending less energy and have a lower temperature

Answer 228

Umbra is ~3800K Penumbra is ~5600K

Answer 229

If the difference in longitude (ΔL) of a sunspot occurs in a time interval, then rotation period (T) can be calculated by: T . . 360° —- = —— Δt . . ΔL

Answer 230

The earliest Nuclear Fusion is when hydrogen (H) nuclei fuse into Helium (He) nuclei

Answer 231

The temperature has to be high enough to overcome the mutual electrostatic repulsion of the positively-charged nuclei

Answer 232

The Proton-Proton or Deuterium-Deuterium chain

Answer 233

At each stage in the chain, mass (m) is lost and converted into energy (E). This is in accordance with Einstein’s equation E=mc², where c is the speed of light

Answer 234

The Sun loses 4 million tonnes of mass every second, this is insignificant as the Sun’s total mass is 2.0 × 10²⁷ tonnes

Answer 235

Radiative zone

Answer 236

This zone is where the energy in the form of photons (gamma-radiation) is transferred in a random manner due to the scattering of photons by electrons outwards

Answer 237

The convection zone

Answer 238

~200 000 km

Answer 239

The convection zone is where the thermal energy is transported to the photosphere by rising convection currents of hot plasma

Answer 240

The photosphere

Answer 241

The photosphere is ~2 million K at the base. At the visible part of the photosphere, the temperature is 5800 K

Answer 242

The Sun radiates energy in the form of visible light but also to a lesser extent of infra-red, ultra-violet and X-Radiation

Answer 243

The chromosphere and corona

Answer 244

2000 km thick

Answer 245

400 K - 100 000 K at the top

Answer 246

2 million K

Answer 247

The corona can extend outwards for millions of km into space

Answer 248

An outflow of charged particles (mostly protons and electrons)

Answer 249

The Corona

Answer 250

Coronal holes

Answer 251

Coronal mass ejections and Solar Flares

Answer 252

Solar wind is responsible for aurora and the creation of cometary tails

Answer 253

The butterfly diagram is a diagram that shows the solar cycle of sunspots. The cycle begins with a few spots at mid latitude. The numbers of sunspots fall and rises, and they drift towards the solar equator

Answer 254

A Red Supergiant collapses

Answer 255

A Type Ia Supernova occurs when Red Giant star is in a binary system with a white dwarf. Over time, the white dwarf will gravitationally steal matter from the Red Giant, resulting in the increase of mass. It will surpass the Chandrasekhar limit and the electron degeneracy pressure will be insignificant in preventing the collapse, resulting in a supernova

Answer 256

A build up of of magnetic energy which is released from a sunspot

Answer 257

Particles that are emitted from all over the Sun. They are slowed by the magnetic fields of the Sun They are mostly charged protons and electrons

Answer 258

During the middle of a Sunspot cycle where there are the most amount of Sunspots

Answer 259

The particles need to be hot enough to withstand the electric repulsive forces. They have to hit each other fast so they need to be at very high pressure (15 Million Kelvin)

Answer 260

Sunspots are black spots on the surface of the Sun that are formed where the the magnetic field leaves the surface. It is a cool area where no convection occurs

Answer 261

Magnetosphere

Answer 262

Local Mean Time - Mean Solar Time In Greenwich _______________________________________ . . . . . . . . . . . . . . . . . . . . . . . 4 =Degrees of Longitude to the East

Answer 263

The First Umbral Contact is when the Moon starts to cover the Sun

Answer 264

The second Umbral contact is when the Moon has just finished covering the Sun

Answer 265

The Moon is on the cusp of leaving the Umbra of the Sun

Answer 266

The fourth Umbral Contact is when the Moon has just left the Sun

Answer 267

When the Moon is too small to fully cover the Sun so a ring of light surround the Sun

Answer 268

An Annual Solar Eclipse occurs when the Moon’s orbit is in an apogee and the the Moon appears too small to cover the entire Sun compared to normal eclipses

Answer 269

An accretion disk consists of hot, swirling gas captured by a white dwarf ( or neutron star or black hole ) from a binary companion star

Answer 270

A white dwarf supernova can occur only in a binary system, and all such events are thought to have the same luminosity

Answer 271

Photosphere Convective zone Radiative zone Core

Answer 272

A H-alpha filter makes the observation of the Sun safe as the intensity of light received from the Sun is reduced

Answer 273

The Sun rotates faster at the equator then the poles

Answer 274

2 million K

Answer 275

15 million K

Answer 276

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune

Answer 277

Mercury Venus Earth Mars

Answer 278

They are all relatively small rocks surrounding iron cores

Answer 279

Jupiter Saturn Uranus Neptune

Answer 280

The gaseous planets have liquid interiors and substantial atmospheres of hydrogen and Helium with traces of methane and ammonia. They also have complex ring systems and large amounts of Moons

Answer 281

Jupiter Saturn Uranus Neptune

Answer 282

They lack the gravitational force needed to sweep debris out of their orbit. They also don’t consistently stay in the zodiacal band

Answer 283

All the dwarf planets (except Ceres) are found in the Kuiper belt

Answer 284

Ceres is found in the Asteroid belt

Answer 285

Ceres, Pluto, Eris and Makemake

Answer 286

Small Solar System Objects which include asteroids, meteoroids and comets

Answer 287

Most Asteroids are found in the Asteroid Main Belt between the orbits of Mars and Jupiter

Answer 288

Asteroids range from ~10 m to ~1000 km; most have irregular shapes

Answer 289

Kuiper Belt

Answer 290

< 200 years

Answer 291

The gravitational influence of Neptune nudge the comets into solar orbits; these have a subset period of < 20 years

Answer 292

Oort Cloud, a spherical distribution of icy bodies about halfway to the nearest star

Answer 293

> 200 years

Answer 294

1. They have unpredictable orbits 2. Highly-inclined to the plane of the Solar System 3. Some orbiting in the opposite sense to that of the planets

Answer 295

Rarefied gasses and dust envelop the nucleus of dust and ice; eventually, one or more tails develop that can be several million kilometres long

Answer 296

The tail and the comet become less visible. The comet ceases to be influenced by solar radiation, fades from view and returns to the outer Solar System

Answer 297

A comet’s ion tail is long, straight and predominantly blue in colour

Answer 298

Meteoroids are particles of dust, rock and mixtures of stone, ice and metal that are in orbit around the Sun

Answer 299

When a particle enters the Earth’s atmosphere, air resistance converts kinetic energy into thermal energy, heating the particles. This results in a streak of light visible in the night sky that is called a shooting star or meteor

Answer 300

A Meteor Shower is when the Earth passes through a meteoroid stream in the wake of a comet, many more meteors are visible

Answer 301

The radiant is the point where the individual meteors appear to diverge from a vanishing point. This is simply due to perspective. The shower is named after the nearest constellation

Answer 302

Fireballs are when larger meteoroids enter the atmosphere and produce bright light. These survive their journey, reaching the Earth’s surface as meteorites

Answer 303

AU is an astronomical unit that is equal to the mean distance from the Earth to the Sun. 1 AU = 150 million km

Answer 304

Refractors and Reflectors

Answer 305

The job of the Objective element is to collect as much light as possible and focus the light to a small bright image

Answer 306

The eyepiece magnifies the image of the objective element so the images can be observed in a higher resolution and are much brighter

Answer 307

The telescope’s aperture is the size of the hole that light goes through

Answer 308

The more light enters the telescope, making images brighter The higher amount of detail that can be resolved

Answer 309

The resolution depends on the wavelength of light entering the telescope: the longer the wavelength, the poorer the resolution. So, red nebulae are not as good as that in blue nebulae surround young stars

Answer 310

The light grasp is a measure of how much light is captured by the objective element; this depends on the cross-sectional area. The area depends on the square of the diameter of the objective lens or mirror. light grasp α area α (diameter of the objective element)²

Answer 311

Magnification depends on the ratio of focal length of the objective (fo) and eyepiece (fe)

Answer 312

magnification = focal length of objective = fo . . . . . . . . . . . . . ————————————- . .— . . . . . . . . . . . . . focal length of eyepiece . . fe

Answer 313

The shorter focal length, the greater the magnification

Answer 314

A Barlow Lens allows eyepieces to be slotted into it. The optical elements of a Barlow lens increase the magnification by a factor of 2 or 3

Answer 315

Field of View of a telescope is the circle of sky that is visible through its eyepiece

Answer 316

Field of View of a telescope is the circle of sky that is visible through its eyepiece

Answer 317

Field of View is measured in degrees or minutes of arc (arcmins) where 1°=60’

Answer 318

Astronomers prefer to use reflector telescopes as they can have larger objective apertures that can be supported by the telescope. Also, it is possible for mirrors to reflect light with almost no loss in intensity or chromatic abberation

Answer 319

Chromatic Aberration is when lenses tend to focus different wavelengths of light to slightly different points. This causes images to be blurred and unclear

Answer 320

Chromatic Aberration - Long in size which makes viewing impractical

Answer 321

1. Fly-by Missions 2. Orbiters 3. Impactors 4. Landers

Answer 322

Fly-by missions are missions that analyse and explores many targets, without getting caught in the gravitational pull of the target. Missions include 𝘝𝘰𝘺𝘢𝘨𝘦𝘳𝘴 𝘐 and 𝘐𝘐 (that visited the outer planets) and 𝘕𝘦𝘸 𝘏𝘰𝘳𝘪𝘻𝘰𝘯𝘴 (that explored Pluto and the outer Solar System)

Answer 323

Orbiter missions are probes that get caught in the gravitational fields of the target. Missions include the 𝘔𝘢𝘨𝘦𝘭𝘭𝘢𝘯 probe that mapped the planet Venus using radar, 𝘋𝘢𝘸𝘯 (that made detailed studies of asteroids Ceres and Vesta) and 𝘑𝘶𝘯𝘰 that measured Jupiter’s composition and magnetosphere

Answer 324

Impactor missions are missions that are planned to crash onto a target to create an artificial quake. Examples include the third stages of 𝘚𝘢𝘵𝘶𝘳𝘯 𝘝 spaceship that were impacted onto the lunar surface to cause artificial moonquakes and the 𝘋𝘦𝘦𝘱 𝘐𝘮𝘱𝘢𝘤𝘵 probe which crashed on Comet Temple 1 to study the internal composition of a comet

Answer 325

Missions where the impact is controlled and the probe touches down intact on the surface. Example include 𝘏𝘶𝘺𝘨𝘦𝘯𝘴 landing on Saturn’s moon Titan, the 𝘚𝘱𝘪𝘳𝘪𝘵 and 𝘖𝘱𝘱𝘰𝘳𝘵𝘶𝘯𝘪𝘵𝘺 on Mars and 𝘗𝘩𝘪𝘭𝘢𝘦 onto the comet 67P/Chunyumov-Gerasimenko in order to perform a chemical analysis of its water content

Answer 326

A comet’s ion tail consists of charged ions that have been excited by the particles in the solar wind and emit light by fluorescence when they de-excite

Answer 327

A stationary point is when a planet’s motion changes direction

Answer 328

A Protoplanetary disc is a rotating disk of dense gas and dust surrounding a newly formed star

Answer 329

A frost line marked the boundary beyond which it was cold enough for volatiles to freeze onto tiny particles of dust; within the frost line, only metals and rock could condense into solid grains

Answer 330

Accretion is when small grains of solid material collide and stick into each other forming larger flakes. These collide into other pieces forming larger and larger bodies

Answer 331

After ~100 million years, the accumulated pieces formed the metallic and silicate cores of the planets

Answer 332

Beyond the frost lines, the cores of the protoplanets grew to much bigger sizes due to the large abundance of ices. The gravitational attraction of these massive cores were able to draw in large amounts of hydrogen and helium that were present in the outer solar system to form the atmospheres of four gas giant planets

Answer 333

1. A planet’s or moon’s mass 2. Temperature 3. Magnetic Field

Answer 334

The hotter the temperature, the faster the gas molecules move, making them more likely to escape the gravitational attraction of the planet or moon

Answer 335

The greater the mass, the greater the gravitational pull on the atmosphere

Answer 336

The 50 bodies collided, broke apart and re-formed a significant number of times before becoming an ordered system with stable orbits around the Sun

Answer 337

Mercury’s iron core occupies over 60% of its volume; the planet is thought to have lost most of its rocky interior due to a collision with a protoplanet about one sixth of its size

Answer 338

The backwards spin of Venus and sideways spin of Uranus suggests that these two planets had significant collisions during the Solar System’s history

Answer 339

Tidal heating is when internal friction and the interior of a Moon becomes warm

Answer 340

Thermal energy is produced at the expense of rotational kinetic energy, and the moon’s spins slows down a little. Over time, this results in a synchronised rotation where the Moon’s rotational and orbital period are the same

Answer 341

The Internal friction produces energy which heats up the moon

Answer 342

Tidal heating doesn’t end because most moon orbits aren’t perfectly circular: A varying orbital speed means that tidal bulges still occur and oscillate about a mean position

Answer 343

Orbital Resonance

Answer 344

Orbital Resonance works when the different moons are aligned and and ‘tugged’ out of shape meaning they don’t have circular orbits

Answer 345

Tidal heating is responsible for the molten layers that are beneath the rocky or icy crusts of large moons. This is responsible for active volcanoes or cryovolcanoes (ice volcanoes)

Answer 346

If a moon’s internal elastic forces that resist deformation aren’t strong enough, the tidal forces will break up the body or prevent one from forming

Answer 347

Planetary rings are believed to be formed after a moon was broken up by tidal forces and the fragments spread around the planet

Answer 348

The Roche limit is the minimum distance a large satellite can approach its parent body without being torn apart

Answer 349

The Lagrangian points are the stable positions near large objects in orbit. These are the points where a small object is able to orbit

Answer 350

The Lagrangian points in a two body system (an example is the Earth and Sun) at which their combined force of gravity is equal to the centripetal force needed to maintain the circular motion of a third object (a satellite)

Answer 351

Exoplanets are planets that orbit a star outside the Solar System

Answer 352

1. Astrometry 2. Transit Method 3. Radial Velocity Method

Answer 353

Astrometry is when massive Exoplanets orbit their star and their combined gravitational pull can cause the star to move or wobble slightly in its position around the common centre of gravity

Answer 354

The Transit Method is when you can detect an Exoplanet transiting across the host star. This causes a very small (1%) drop in brightness for the duration of their transit

Answer 355

The radial velocity method is when the slight wobbling of a star due to orbital motion of the exoplanet can be detected as small Doppler-shifts in the wavelengths of the the star’s spectral lines as it moves in the line-of-sight of the observer

Answer 356

Astronomers uses spectroscopy to reveal small changes in a stars spectral lines

Answer 357

The Radial Velocity Method

Answer 358

Carbon and Water

Answer 359

Carbon has the ability to make interesting compounds such as amino acids and can form more complex organic molecules

Answer 360

Water in its liquid form is an excellent solvent and acts as a transport mechanism for many nutrients

Answer 361

The Habitable Zone is the area a planet must be if liquid water is to be located on its surface

Answer 362

The Drake Equation is the equation that attempts to estimate the likelihood of intelligent life in our galaxy

Answer 363

Saturn’s Moon Titan Jupiter’s moon Europa Saturn’s moon Enceladus

Answer 364

Saturn’s moon titan has seas of liquid hydrocarbons

Answer 365

Jupiter’s moon Europa contains an ocean of liquid water under its outer shell

Answer 366

Saturn’s moon Enceladus has eruptions of salt water, hydrocarbons and carbon

Answer 367

Search for Extraterrestrial Intelligence

Answer 368

1. Number of Stars in our galaxy 2. Number of earth-like planets in the Habitable zone 3. Fraction of stars with orbiting planets 4. Fraction of Earth-like planets on which life evolves 5. Fraction of Planet’s life for which intelligent civilisations live 6. Fraction of planets where life is intelligent and develops technology to communicate with us

Answer 369

Extremophiles are life forms that can live in extreme temperatures, conditions, high pressure and high concentrations of salt water

Answer 370

diameter = speed × time interval of beginning a transit to being fully in the disk of the parent star

Answer 371

2 l.y. (2 light years)

Answer 372

Elliptical and parabolic

Answer 373

Deposits by comets and large asteroids

Answer 374

Iron Stone Stoney-Iron

Answer 375

Iron and Nickel

Answer 376

The cores of asteroids

Answer 377

Oxygen and Silicon

Answer 378

1. Giant Impact Hypothesis which formed the Moon 2. Uranus’ sideways spin 3. Venus’ backwards spin 4. Impact craters on the Moon, Mars and asteroids 5. Large Iron Core of Mercury

Answer 379

Rocky Matter was ejected from Mars following a collision with a large meteoroid

Answer 380

Mars’ Deimos and Phobos

Answer 381

After Mars’ formation, Mars probably has a molten core in which electric currents could flow and produce a magnetic field. Mars’ magnetic field was able to deflect particles of solar wind around the planet. As Mars cooled, its molten core solidified and currents could no longer flow meaning the Magnetic field was lost The solar wind was no longer deflected so blew away particles in Mars’ atmosphere

Answer 382

Water and ice is ejected from Enceladus’ geysers. Some water and ice falls back onto Enceladus and some is captured by the gravitational field of Saturn forming its E-ring

Answer 383

Mimas (One of Saturn’s moon)

Answer 384

Gravitation and Elastic

Answer 385

The moon could have a small diameter and/or the distance between the moon and its parent planet is large

Answer 386

Tidal forces are gravitational in origin. Gravity follows an inverse square law. The moon must have a large enough diameter for the difference in gravitational pull on the ‘near’ and ‘far’ side of the moon to be significant/greater than elastic forces

Answer 387

For our Solar System, the Frost Line was about 5 AU from the Sun. Within the frost line, volatile ices were unable to condense due to the high temperatures. However, beyond the Frost Line, it was cold enough for ices to condense and these are thought to have caused the significantly larger cores of the gas giants

Answer 388

Solar wind is most likely reason for ‘blowing’ light gases toward the Outer Solar system. Solar wind is ‘strongest’ closer to the Sun i.e. in the inner Solar System

Answer 389

Magnitude is the measure of a brightness of a star

Answer 390

The magnitude difference of 1 corresponds to the fifth root of 100≈2.5

Answer 391

Apparent magnitude is how bright a star seems from Earth

Answer 392

1. The total energy by the star in the visible region 2. The distance to the star 3. The amount of interstellar gas and dust that reflects and absorbs light 4. The amount of light absorbed and scattered by the Earth’s atmosphere

Answer 393

Absolute magnitude is how bright a star would be if all stars are 10 parsecs away

Answer 394

M=m+5- 5log(d) M=absolute magnitude m=apparent magnitude

Answer 395

Spectroscopy

Answer 396

Spectroscopy is when you collect light with the aid of a telescope and then diffract it to create a spectrum

Answer 397

When you do a spectroscope, there are a set of darker lines. The spectral lines correspond to exact wavelengths at which atoms in the outer layers of stars absorb light; each element has its own unique set of wavelengths

Answer 398

Spectral types

Answer 399

Astronomers examine the ratios of hydrogen: helium: other elements

Answer 400

O B A F G K M

Answer 401

The H-R diagram is a scatter graph the classify’s stars in accordance to their luminosity, spectral type, colour, temperature and evolutionary stage

Answer 402

A star’s luminosity or absolute magnitude is plotted against either spectral type or temperature

Answer 403

The main sequence stars lie in a band running from top left to bottom right

Answer 404

Giants and Supergiants stars lie above the main sequence band

Answer 405

Red or Blue

Answer 406

White dwarfs lie below the main sequence band towards the left

Answer 407

1 l.y = 9.5 × 10 ¹²

Answer 408

1 pc = 3.1 × 10 ¹³

Answer 409

1 pc = 3.26 l.y

Answer 410

Minutes of Arc is one degree split into 60 minutes of arc. 1 arc minute is further split into arc seconds where one degree is 3600 arc seconds

Answer 411

Heliocentric Parallax

Answer 412

Parallax is when the position of a near object differs greater in comparison to distant objects when viewed from different places

Answer 413

Variable stars are stars that vary in brightness

Answer 414

1. Changing physical quantity such as size 2. Changes in the light reaching Earth

Answer 415

Graphs of apparent magnitude against time

Answer 416

Intrinsic and Extrinsic variables

Answer 417

Cephied Variables are when the Star actually pulsates. When it’s larger, it has a greater magnitude, and therefore it’s brighter

Answer 418

Binary stars are when there is a bright primary star and a dimmer secondary star that orbit around their mutual centre of gravity

Answer 419

When the secondary eclipses the primary, there is a large drop in intensity

Answer 420

When the primary star eclipses the secondary star, there is a small drop in intensity

Answer 421

Radio telescopes consist of a large concave dish that reflects and focuses radio waves into an antenna. Here, the antenna converts the radio waves into electrical signals that can be stored and processed

Answer 422

Radio telescopes are large so they can achieve the best possible resolution by collecting as much radio waves as possible

Answer 423

Aperture synthesis is when multiple telescopes are linked electronically to study the same source of radio waves. This converts many telescopes into one large one with an aperture equivalent to the largest distance between individual telescopes

Answer 424

The air is dry and steady. Also, there is a lack of clouds which obscure your view

Answer 425

The satellite is above atmosphere where there is: - no air to blur or absorb light - no day-night cycle where your viewing times are restricted - no light pollution from skyglow meaning it is in the optimum position to place a telescope in space

Answer 426

Space telescopes have limited lifetimes, very difficult to construct, launch and maintain

Answer 427

1. Quasars 2. The structure and rotation of our galaxy 3. Pulsars 4. Protoplanetary discs 5. Jets from black holes 6. SETI (Search for extraterrestrial intelligence)

Answer 428

1. Protostars 2. Interstellar dust and molecular clouds 3. ‘Hotspots’ on the moon

Answer 429

Corona and chromosphere structure of young stars

Answer 430

1. Active galaxies 2. Accretion disks surrounding black holes 3. Supernova remnants

Answer 431

Gamma ray bursts in distance galaxies

Answer 432

All wavelengths other than optical or radio, need to be put on fixed observing platforms orbiting the Earth. However, Infrared observatories can be sited on high mountains

Answer 433

M = m + 5 - 5log(d) M=absolute magnitude m=apparent magnitude d= distance

Answer 434

First, you obtain a spectrum of the star and determine its spectral class. Then, using the H-R diagram you get its absolute magnitude (you use the main sequence band). You then observe the star to get its apparent magnitude. Finally, you use the distance modulus formula to calculate 𝗱

Answer 435

α (alpha), β (beta), γ (gamma), δ (delta), ε (epsilon)

Answer 436

light intensity is proportional to 1 . . . . . . . . . . . . . . . . . . . . . . . .————– . . . . . . . . . . . . . . . . . . . . . . . .distance²

Answer 437

intensity of light from α . (distance β)² ——————————— = —————— intensity of light from β . (distance α)²

Answer 438

Luminosity against Spectral type

Answer 439

Temperature increases to the left and Absolute magnitude increases downwards

Answer 440

Light passing through the outer layers a star is made of all wavelengths / energy. Some of this light has the correct wavelength/energy to excite atoms in the star’s outer layers. When the atoms de-excite they emit radiation/photons of the same wavelength/energy but in a random direction and not necessarily ‘outwards’. The wavelengths / energies at which these ‘reactions’ occur depends on the chemical element. Light received on Earth is dimmer and so darker at these wavelengths

Answer 441

Cepheid variable

Answer 442

Cataclysmic variable stars are stars which irregularly increase in brightness by a large factor, then drop back down to a inactive state

Answer 443

For most of the time, the primary and secondary stars are not aligned. This is their constant brightness. The larger/primary ‘dip’ in a light curve occurs when the dimmer/secondary star is directly in front of the brighter/primary star. The smaller/secondary ‘dip’ occurs when the secondary star is behind the primary star. This time, the corresponding drop in intensity is not as significant

Answer 444

Square Kilometre Array

Answer 445

The process of linking multiple telescopes together to increase aperture size

Answer 446

Stars near the horizon appear higher in the sky than they actually are

Answer 447

Diffraction grating

Answer 448

Supernova remnants and Planetary Nebulae

Answer 449

Gamma X-Ray UV Visible IR Microwave Radio

Answer 450

Nebulae are large interstellar clouds of dust and gas

Answer 451

Open clusters are a group of young stars that formed from the same giant molecular cloud. They all are roughly the same age

Answer 452

Globular clusters a group of older stars

Answer 453

Open clusters are found on the spiral arms of the Galaxy

Answer 454

Globular clusters are found in a ‘halo’ around the centre of the galaxy

Answer 455

The Messier Index is a catalogue of 110 astronomical objects that can be observed

Answer 456

All stars originate from the gravitational collapse of of a cool, dense molecular cloud of gas and dust that are found in the spiral arms of galaxies. As the cloud collapses, it becomes unstable and fragments into smaller clumps (protostars) that will form the cores of individual stars

Answer 457

Gravitational potential energy is converted into kinetic energy and its temperature increases. It eventually becomes hot enough for the fusion of hydrogen into helium

Answer 458

Radiation Pressure is the pressure that is exerted on a surface due to the exchange of momentum between an object and the electromagnetic field. The Radiation Pressure of stars is caused by the nuclear fusion of elements

Answer 459

During the main sequence stage, radiation pressure and gravity balance. This stops any further gravitational collapse

Answer 460

A star is in the main sequence stage for ~90% of its lifetime

Answer 461

The Chandrasekhar Limit is the maximum mass of a stable white dwarf

Answer 462

The maximum limit is a Sun with a core 1.4 times the mass of the Sun

Answer 463

When the generation of energy stops, the radiation pressure becomes zero and the star gravitationally collapses. This raises the temperature of the star and causes the fusion of hydrogen again but this time in a shell around the core. The helium core further contracts which increases the rate of energy generated. This makes the star expand and form a Red Giant

Answer 464

If the core becomes hot enough, helium will fuse into carbon

Answer 465

A planetary nebula is a nebula that is formed by an expanding shell of gas from an ageing star

Answer 466

Electron Degeneracy Pressure

Answer 467

Electron Degeneracy Pressure is because the electrons cannot be squeezed together any closer and so resist any further compression

Answer 468

A White Dwarf

Answer 469

A Black Dwarf

Answer 470

Black Dwarfs form after a white dwarf cools down and loses its energy

Answer 471

If a star has a core mass greater than the Chandrasekhar limit, the star will continue to collapse and will be able to fuse carbon into Neon. Fusion continues until iron is formed in the core

Answer 472

The collapse is stopped by the neutron degeneracy pressure

Answer 473

The electrons are forced into protons to form a solid core of neutrons, and these neutrons prevent being compressed further

Answer 474

The star becomes a neutron star

Answer 475

The Star will turn into a red Supergiant after it is a main sequence. The neutron degeneracy pressure is insufficient to prevent the gravitational collapse after the supernova and the core collapses further to form a black hole

Answer 476

An emission nebula is a cloud of ionized gas. The most common source for ionizations are high energy photons emitted from a nearby star

Answer 477

Reflection Nebulae are clouds of dust which are simply reflecting the light of a nearby star or stars. The nearby star or stars are not hot enough to cause ionization in the gas of the nebula like in emission nebulae but are bright enough to give sufficient scattering to make the dust visible

Answer 478

Absorption nebulae are nebulae that can be seen because they obscure, or absorb, the light coming from stars or bright nebulae behind them

Answer 479

Averted vision means looking slightly to the side of a faint, extended object so that light falls onto the rods (not the cones) of the eye’s retina In dark conditions, the cones (which lie where the optical axis joins the retina) are not sensitised, but the rods (which lie adjacent to the optical axis) are

Answer 480

Sir Patrick Moore

Answer 481

Diffraction spikes are when some stars appear to have crosses through them

Answer 482

Gravitational Waves and Supernovae

Answer 483

Electron degeneracy Pressure

Answer 484

Old and Dim

Answer 485

Young and bright

Answer 486

Neither emits enough radiation to be ‘bright’ enough to register on the luminosity/absolute magnitude/vertical axis

Answer 487

Via Lactea

Answer 488

Barred Spiral Galaxy

Answer 489

In the Spiral Arms

Answer 490

The Centre of the Galaxy is blocked by dust and dense gas

Answer 491

The Doppler Principle is that relative motion changes the frequency or wavelength of observed waves. We notice this change mainly with sound waves

Answer 492

The object is moving away from us

Answer 493

The source is moving towards us

Answer 494

The received wavelengths are supposed to be 21 cm, but they aren’t exactly. This will tell us the relative velocities of the different parts of the Milky Way and how it’s rotating

Answer 495

Redshift is receding sources of waves

Answer 496

Blueshift refers to sources that are approaching us

Answer 497

Hubble Classification System

Answer 498

Tuning Fork Diagram

Answer 499

Vast clouds of gas and dust collapsed gravitationally, allowing stars to form

Answer 500

Lumps of matter were already present in the Universe. They clumped together under their mutual gravitational attraction to form galaxies

Answer 501

Elliptical

Answer 502

Active galaxies are galaxies that have a small core of emission in a normal galaxy. It emits huge amounts of radiation in wavebands such as X-ray and radio regions

Answer 503

An Active Galactic Nucleus is a compact region at the centre of a galaxy that have a much higher luminosity over a portion of the electromagnetic spectrum which indicates that the luminosity isn’t produced by stars

Answer 504

Seyfert Galaxies are galaxies that have a bright nucleus and emit strongly in the IR, UV and X-ray regions

Answer 505

Seyfert galaxies were discovered by Carl Seyfert in 1943

Answer 506

A quasar is an extremely luminous AGN that emits strongly in the UV and X-ray regions

Answer 507

Quasars appear star-like on images and have large redshifts

Answer 508

Blazars are compact quasars where the galactic jets are pointing towards us

Answer 509

Any five of: Andromeda Galaxy Large Magellanic Cloud Small Magellanic Cloud Triangulum Galaxy Milky Way Pegasus Dwarf etc.

Answer 510

Virgo Cluster

Answer 511

Laniakea Supercluster

Answer 512

Redshift is when objects moving away from us, are shifted towards the red end of the spectrum and the wavelengths of spectral lines become longer than the same corresponding wavelengths measured in a laboratory on Earth. It is an example of the Doppler Principle

Answer 513

λ - λ₀ . .v ------- = -- . .λ₀ . . .c λ = Observed wavelength λ₀ = True Wavelength v = Velocity c = Speed of light

Answer 514

v = H₀d H₀ = Hubble's Constant v = Velocity d = Distance

Answer 515

Calculate the gradient of a v-d graph

Answer 516

The accepted value is 68 km/s/Mpc

Answer 517

The Big Bang is a rapid expansion from an extremely high density to create the universe

Answer 518

The Steady State Model suggests that the the Universe always has been expanding. The density of the Universe is constant over time with new matter being constantly created

Answer 519

A Cyclic Universe suggests that there have been a series of Big Bang/ Big Crunch scenarios and will continue in the future

Answer 520

Big Bang and Cyclic models

Answer 521

Quasars Cosmic Microwave Background (CMB) Radiation Hubble Deep Field (HDF) image

Answer 522

Quasars are only found with high redshifts, which implies that they lie great distances from us and were created when the Universe was very young; the fact that quasars were more common in the early Universe compared with today which supports the nature of the Big Bang model

Answer 523

Russian cosmologist George Gamow predicted if the early Universe was hot and dense, it would’ve cooled and expanded to a temperature just above absolute zero. In 1965, Robert Wilson accidentally discovered CMB radiation from all parts of the sky that corresponded to a temperature of 2.7 K

Answer 524

These images were a series of long exposure images of empty space with a small field-of-view of 2.6 arcmins but the image revealed thousands of distant old galaxies, implying that the early Universe was very different from how it appears today

Answer 525

1. Decelerating Universe 2. Coasting Universe 3. Accelerating Universe

Answer 526

A decelerating Universe leads to a collapse in a ‘Big Crunch’

Answer 527

A coasting Universe will continue to expand at a constant rate

Answer 528

The expansion of the Universe is accelerating due to dark energy, a mysterious repulsive force, which increases the rate of expansion

Answer 529

Gravitational Lensing

Answer 530

Gravitational Lensing is the apparent bending of light from galaxies to form multiple images of the same galaxy

Answer 531

WIMPs (Weakly Interacting Massive Particles)

Answer 532

Velocity and Distance are directly proportional to each other

Answer 533

c(Δλ) -------- = v . .λ c = speed of light Δλ = Change in wavelength λ = Actual Wavelength v = Recession velocity

Answer 534

Blueshift is when light is shifted towards the shorter end of the spectrum, indicating that it is moving towards us

Answer 535

The Equant is a mathematical concept used to explain observed speed changes in planetary orbit in a geocentric system

Answer 536

The Epicycle is a geometric model that was used to explain the apparent change in speed and direction of the apparent motion of the planets. It was used in particular to explain retrograde motion

Answer 537

Megaparsec

Answer 538

The basic unit is the kilometre per second per megaparsec. The kilometre and megaparsec are both units of distance/length. These can effectively cancel to leave the unit as the ‘per second’

Answer 539

Hubble time is the time for which the Universe has been expanding

Answer 540

Normal matter - 5% Dark Matter - 25% Dark Energy - 70%

Answer 541

The age of the Universe - 14 billion years

Answer 542

Hubble length is the length of the observable Universe

Answer 543

1H+1H →2H+0e+0v 1 . . 1 . . . .1. . . 1 . . .0 2H+1H→3He 1 . . .1 . . . 2 3He+3He→4He+1H+1H 2. . . .2 . . . . 2 . . . 1 . . 1

Answer 544

In 1543, Copernicus formulated the Heliocentric system, with the Sun at the centre rather than the Earth

Answer 545

In 1572, Brahe discovered a supernova in Cassiopeia

Answer 546

In 1608, Lippershey invented the telescope

Answer 547

In 1609, Galileo discovered the 4 Jovian moons, the Moon’s craters and the Milky Way Galaxy

Answer 548

In 1609, Kepler announced the first and second laws of planetary motion. He announced the third law in 1619

Answer 549

The first law states that planets move in elliptical orbits around the Sun at one focus of each ellipse (the other is empty)

Answer 550

Kepler’s second law states that an imaginary line from the Sun to a planet sweeps out equal areas in equal intervals of time

Answer 551

Kepler's third law states that the square of the orbital period (T) of a planet is proportional to the cube of its mean distance (r) from the Sun T² --- = A constant r³ or t²=r³

Answer 552

In 1666, Cassini noticed the Martian Polar Ice Caps

Answer 553

In 1668, Newton built the first reflecting telescope. In 1687, he published The Theory Of Universal Gravitation

Answer 554

Newton discovered that the force of weight is directly proportional to the product of the masses of the two objects

Answer 555

Newton found that the strength of gravity follows an inverse square law, this means that the strength of gravity goes down by the increase of distance squared F×d²=k F = Force (Newtons) d= Distance (metres) K= a constant

Answer 556

In 1705, Halley computed the orbit of the eponymous Halley’s Comet using Newton’s laws

Answer 557

In 1781, Charles Messier published an astronomical catalogue consisting of nebulae and star clusters that came to be known as 110 ‘Messier objects’

Answer 558

In 1842, Doppler discovered the ‘Doppler effect’ of moving stars

Answer 559

In 1905, Albert Einstein came up with the Theory Of Relativity in ‘On The Electrodynamics Of Moving Bodies’. In 1916, he introduced the General Theory of Relativity

Answer 560

During 1911-14, they introduced the H-R Diagram that shows how the characteristics of stars are related

Answer 561

The main sequence band

Answer 562

The Bayer system uses Greek letters to represent relative magnitudes

Answer 563

A spectroscope is a device for producing and recording spectra for examination

Answer 564

Astronomers use spectroscopes to investigate the following properties of stars: Chemical composition Temperature Radial Velocity Stellar Classification (OBAFGKM)

Answer 565

Edmond Halley devised a method of determining the size of an Astronomical Unit by observing transits of Venus

Answer 566

A transit observations enabled the absolute size of the Solar system to be determined

Answer 567

Reflectors and refractors

Answer 568

Convex Lens

Answer 569

Parabolic (Concave) Lens

Answer 570

It collects as much light as possible and focuses it into a small, bright image

Answer 571

An eyepiece lens magnifies the image given by the objective element so we can see an image in high resolution

Answer 572

1. More light enters the telescope; making the image brighter 2. There is a higher resolution and a bigger amount of detail

Answer 573

The wavelength of light that is entering the telescope; a red nebulae has a lower resolution compared to a blue nebulae as red has a longer wavelength

Answer 574

The ratio of the lengths of the objective and and eyepiece

Answer 575

. . . . . . . . . . . . . . .focal length of objective. . . fo magnification = ———————————– = —- . . . . . . . . . . . . . . .focal length of eyepiece. . . fe

Answer 576

1. Use eyepieces of different focal lengths; the shorter the focal length, the greater the magnification 2. Use a Barlow Lens

Answer 577

A Barlow lens a piece of kit for astronomers that slots into the eyepiece and increases the magnification by 2x or 3x

Answer 578

The field of view of a telescope is the circle of the sky that is visible through the eyepiece

Answer 579

A concave mirror that transforms a plane wave into a spherical wave that moves into the centre

Answer 580

1. Commercial and sports floodlights 2. Urban street lamps and motorway lights 3. Domestic and industrial security lights 4. Lights above car parks and shopping centres

Answer 581

1 AU = 150 Million km = Distance from the Earth to the Sun

Answer 582

1 l.y. = 9,500,000,000,000 km= 9.5 billion km

Answer 583

1 pc = 3.26 l.y. = 3.1 × 10¹³ km

Answer 584

An H-Alpha filter is a filter which is designed to transmit a narrow bandwidth of light. It can be used to observe the features of the Sun

Answer 585

Dark Adaption is an observing technique where the observer spends time to allow the retina’s rods to desensitise so dimmer stars become more visible

Answer 586

A reflecting telescope consists of a Concave mirror and Convex lens

Answer 587

Converging mirror

Answer 588

Newtonian Reflector

Answer 589

Newtonian Reflector

Answer 590

Cassegrain Reflector

Answer 591

A finderscope is a smaller telescope attached to larger reflectors

Answer 592

Resolution

Answer 593

A Keplerian refractor consists of two concave lenses whereas, a Galilean refractor has one

Answer 594

Resolution of a telescope proportional to the diameter of the objective element

Answer 595

Keplerian Refractor

Answer 596

1. Higher magnifications 2. Larger objective diameters 3. Shorter physical lengths

Answer 597

Venus / Orbiter

Answer 598

Pluto & outer Solar System / Fly-by

Answer 599

Comet Tempel 1 / Impactor

Answer 600

Jupiter / Orbiter

Answer 601

Titan / Lander

Answer 602

Unmanned missions are cheaper, there is no danger faced towards humans and there are no communication time delays as the mission is pre-programmed with mission commands without the need for human interference

Answer 603

76P/Churyumov-Gerasimenko / Lander

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GCSE Astronomy - Pearson Edexcel - COMPLETED Flashcards

*NOT MY QUESTIONS, COPIED FROM ANOTHER DECK - CREDIT: ASHRAF AHMED GCSE ASTRONOMY 9-1 FLASHCARDS*

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NOT MY QUESTIONS, COPIED FROM ANOTHER DECK - CREDIT: ASHRAF AHMED GCSE ASTRONOMY 9-1 FLASHCARDS