midterm 1 (ch 1-3) Flashcards
Constellation
- The region of the sky containing the star pattern
- Not a group of star but rather a section of sky, all stars in this section belongs to the constellation
- Stars could be moving in opposite direction and could be very far apart but are named because that’s how they appear to us
Asterism
- A named grouping of stars that is not one of the recognized constellations, due to boundaries crossing into starts
- The Big Dipper is an asterism. The Great Square of Pegasus is also an asterism.
Greek letters - star brightness
α- the brightest star
β- the second brightest star
γ- the third brightest star
Paradoxical entity
There is no end to space, more and more paradoxical as we expand out of space, defying the laws of physics, universe is finite with no boundaries, even if vehicle was speed of light, never would encounter an end or walls
Where are you and the earth in universe?
Need to understand the laws of physics, gravity and paradoxical entity to understand
Planck Length
Lpl = 1.61619926 x 10^-35 m or 100 billion billion times smaller than an elementary particle!!, limit of physics, stops at this
Milky Way length
lMW = the milky way is about 1,000,000,000,000,000,000 km =10^21 m
Field of View and Astronomical Universe
- Field of view is by 10 x 10, seeing things as 10x farther
- Used to distinguish objects
- Larger than the previous square in the same direction on the celestial sphere.
- As an angular area viewed by the instrument, in the units of square degrees, or for higher magnification instruments, in square arc-minutes
Diameter of Earth
13,000 km
Each Degree of Earth
11.132 km
Earth Rotation
Earth rotates West to east, from the sunset line to darkness (sunsets), seems as if it rotates east to west
The diameter of the Moon
3500 km
Distance From Moon to Earth
380,000km
Astronomical Unit (AU)
1AU= 150 000 000km (the distance from the sun to earth)
Au from Sun to Mercury
0.387 AU
Au from Sun to Venus
0.723 AU
Au from sun to Earth
1.0 AU
Au from the sun to Mars
1.524 AU
Au from the sun to Jupiter
5.203 AU
Au from the sun to Saturn
9.523 AU
Au from the sun to Uranus
19.208 AU
Au from the sun to Neptune
30.087 AU
Au from the Sun to Pluto
39.746 AU
Earth is _____ AU
1
1 light year = ______ AU
63240
Stars and Projection
Way stars are projected onto the sky isn’t an accurate depiction of their location, even at 11000 AU difficult to grasp, 2D image
Why isn’t AU constant?
Increases at 0.045/ cy, may be due to= expansion of universe, loss of solar mass, loss of electromagnetic radiation
The α Centauri System
The (α Centauri) is the brightest star in the southern constellations of Centarus, nearest to the sun, 4.2 ly from earth
The Sun’s Closest Neighbors
α Centauri (Alpha Centauri)
Our Milky Way Galaxy
- It contains 100 x 10^ 9 starsIt has a diameter of 80,000 ly = 8.0 x 10 ^4 ly x 63240 AU/ly = 5.06 x10 ^9 AU
- It is typical galaxy but in many respects larger than most-our galaxy is close to the age of the universe
- Our galaxy is a part of a cluster of other galaxies called local group which contains 55 other dwarf, spiral and other galaxies
Local Group
Cluster of galaxies, different types of galaxies
Super Clusters
Grouping of local group can also be in clusters of clusters, linked to form long filaments and walls, largest structure in universe
Galactic Superclusters
Larger clusters of superclusters, ex; andromeda galaxy
Filaments and Walls
Neuron and filament similarities, similar micro and macro filaments from different galaxies, connected through macro and micro, Filaments between galactic superclusters Pisces-Perseus filament of galaxies
Hubble Telescope
- Can see the filaments connecting two galaxies unifying them, possible it transforms energy, it’s possible galaxies are randomly distributed based on structure, fluctuations and situate them in certain areas of space and time continuum
- May be based on density
- Giant but delicate filaments shaped by a strong magnetic field around the active galaxy NGC 1275
Voids
- Empty space between filament, no distribution, very few or no galaxies
- Cosmic voids are the vast empty spaces between filaments (the largest scale structures in the universe), which contain very few, or no, galaxies
- Voids typically have a diameter of 11 to 150 megaparsecs; –lack of superclusters are sometimes called “supervoids”. —Voids located in high-density environments are smaller than voids situated in low density spaces of the universe.
The Bootes Void
-The Bootes supercluster are famous mainly because they lie next to(and slightly behind) the Bootes Void.- one of the first to be discovered, most famous
Filament Walls in Voids
- Puzzling about filaments, wall and voids we have come to the frontier of the human knowledge
- We are at the limits of possible observation of our universe
How Far Can We See?
- We cannot see more that 13.8 billion light years
- Light that is farther away has not yet reach us
Cosmic Calendar
- Important to understand age of the universe (not known)
- How much universe is expanding
- Time is important
- Believe that’s it’s possible this calendar wasnt enough time for the universe to form
- Gravity and atoms work together to make stars
- Equivalent to the archeology of the universe
- Objects observed appear the way they looked thousands or millions and billions light years ago
Big Bang
13.8 billion years ago, could be start of time
Cosmic Calendar was Devised by the Astronomer Carl Sagen
- In this calendar the big bang happened precisely at midnight of january the 1st
- In January or t=0 the big bang takes place
- February to early march the milky way beings to form, which makes it one of the oldest galaxies
- There is debate about that but, new observational data place it in the domain of 13 billion years
- Around mid-august the solar system starts to form, and by the end of september primitive life exists on the earth
- And until mid- december complex living structures such as invertebrate structures start forming, and until december 25th dinosaurs and ended on december 30th of the cosmic calendar
Solar System
Consists of sun, family of planets and smaller bodies (moons, asteroids and comets)
Star
-Ex; sun, self luminous ball of hot gas that generates its own energy, 110x larger than earth-held together by own gravity and supported pressure of it hot gasses, generates energy through nuclear fusion-gas between stars is filled with gas that forms new stars-sun formed 5 billion years ago
How long does light from the sun take to reach Earth vs pluto and neptune?
takes 8 mins than hours to reach pluto and neptune
Light Years
Light travels in a year (distance), roughly 10^13 or 63000 AU
Galaxy
Cloud of stars, gas, dust, star clusters and nebulae bound together by combined gravity of all matter, orbiting common center of mass
Milky Way
Hazy band of light that circles our sky, produced by glow of our galaxy seen as a cloudy bind of stars in our sky
Milky Way Galaxy
Our galaxy containing our sun, visible at night as milky way, one of the oldest
Spiral Arms
Long spiral pattern of bright stars, star cluster, gas and dust, they extend from center to the edge of the disk of spiral galaxies, wind outward like a disk, ours is approx 80 000 ly in diameter
Andrew Mckellar
First to find existence of matter in space
Which of the following sequences objects is in the correct order of increasing distance?
Venus, Saturn, Moon, Andromeda galaxy, Polaris
Moon, Venus, Saturn, Polaris, Andromeda galaxy
Polaris, Andromeda galaxy, Moon, Saturn, Venus
Andromeda galaxy, Saturn, Venus, Polaris, Moon
Moon, Venus, Saturn, Polaris, Andromeda galaxy
Today the age of the universe is estimated in 13,700,000,000 years
- 37×10^6y
- 37×10^7y
- 37×10^8y
- 37×10^9y
1.37×10^9y
Which statement best describes the Milky Way Galaxy?
It is a spiral galaxy
It is comprised of several smaller galaxies
It is about 1,000 light-years in diameter
It is type of supercluster
It is a spiral galaxy
What is the implication if the distance to the nearest star is 4.2 light-years?
The star is 4.2 million AU away
The light we see left the star 4.2 years ago
The star must be very old
The star must be very young
The light we see left the star 4.2 years ago
If we say that an object is 1,000 light-years away, how does that affect how we see it?
We see it as it looked 1,000 years ago
We see it as it would appear to our ancestors 1,000 years ago
We see it as it looked 1,000 light-years ago
We see it as it is right now, but it appears 1,000 times dimmer
We see it as it looked 1,000 years ago
What is the average distance from Earth to the Sun?
1 AU
How is a planet different from a star?
Planets are larger than stars.
Planets reflect light, while stars produce their own light.
Stars move faster in the sky than planets.
Planets are brighter than stars.
Planets reflect light, while stars produce their own light.
Which of the following is the smallest?
Size of a typical planet
1 AU
1 light-year
Size of a typical galaxy
Size of a typical planet
What is 1.95 billion the same as? Question options:
- 95 × 10^12
- 95 × 10^9
- 95 × 10^6
- 95 × 10^5
1.95 × 10^9
It takes light 1.3 seconds to travel from the Moon to Earth and 8 minutes for light to travel from the Sun to Earth. Which of the following statements is true?
The Sun is 6.2 times farther from
Earth than the Moon
The Sun is 10 times farther from Earth than the Moon
The Sun is 370 times farther from Earth than the Moon
The Sun is 0.10 times farther from Earth than the Moon
The Sun is 370 times farther from Earth than the Moon
How long does it take for light to travel from the Sun to Neptune?
Several seconds
Several minutes
Several hours
Several weeks
Several hours
The speed of light is 3.0×105 km/s, and it takes 1.3 seconds for light to travel from the Moon to Earth. Based on this information, what is the distance from the Earth to the Moon?
390,000 km
230,000 km
- 9 km
- 3 km
390,000 km
Where is Polaris located?
The Solar system
The nearest star to our solar system is alpha Centauri at 4.0x 10^16 m (4.3 ly away). The diameter of the sun is 1.4 x 10^9 m.
How many suns would it take to line up adjacent to each other in order to reach alpha Centauri?
- 9 x 10^6
- 8 x 10^25
- 8 x 10^7
2.8 x 10^7
There approximately 100 billion stars in our galaxy. If there 100 billion observable galaxies in our universe, what is a reasonable estimate for the total number ion the universe?
- 0 x 10^22
- 0 x 10^20
- 5 x 10^15
- 0 x 10^24
1.0 x 10^22
The distance to a supercluster galaxy might be…
100 Mpc
10 Kpc
120 Ly
10 AU
100 Mpc
Approximately 100 Earths would fit inside Jupiter. This Jupiter’s radius must be …………….times larger that Earth’s radius.
100
12
10
1000
10
A spherical particle in the ring of Saturn has radius of about 1m. The surface area of the particle in the area of radiation flow is…
125 m^2
- 14 m^2
- 6 m^2
14 m^2
3.14 m^2
If the landing lights in Denver airport were switched on, then in one second these photons travel to:
New York (1580 km)
Alpha Centauri (40,000,000,000 000 km)
The Sun(150,000,000 km)
Moon (384,000 km)
Moon (384,000 km)
Sirius the brightest star in the sky is about 9 ly away. If the speed of light became half of its present value, how far would Sirius be?
9 ly
18 ly
4.5 ly
32 ly
18 ly
18ly
The Andromeda galaxy is about 2,000,000 ly away. Therefore light started its travel…
1,000,000y
2,000,000y
Just a second ago
Can’t be determined
2,000,000y
What is 5.7×107 the same as?
5.7 million
57 thousand
570 thousand
57 million
57 million
If the distance from the Sun to the Earth is represented by roughly 15 metres, then what would the distance from the Earth to the Moon on the same scale be?
About 30 metres
About 10 metres
About 1 metre
Smaller than the width of your hand
Smaller than the width of your hand
Approximately how many times larger than the diameter of a typical planet (the Earth) is the diameter of a typical star (the Sun)?
10 times
100 times
1000 times
10,000 times
100 times
What does the Solar System contain?
The Sun, its planets, and some smaller bodies
The Sun, galaxies, planets, and stars
The Sun, planets, moons, and stars
The Sun, planets, asteroids, and galaxies
The Sun, its planets, and some smaller bodies
What is the approximate diameter of the Earth?
1 AU
13,000 light-years
13,000 kilometres
1,000,000 kilometres
13,000 kilometres
Which of the following is no longer considered a major planet?
Mercury
Uranus
Pluto
Saturn
Pluto
The Stars
- The great square of pegasus is the boundary between andromeda and pegasus constellation boundaries, black square is the boundaries of the star
- Have coordinated for stars and numbers to find them
Brightness of the Stars can measure brightness using what scale?
the magnitude scale, based on astronomical scale
Magnitude Scale of Stars
- (+) numbers >5 represent objects fainter than the human eye can see
- (-) numbers = brightest stars
- larger the magnitude fainter the star
How many times brighter are 1st magnitude stars than sixth magnitude stars?
100 x
Hipparchus from rhodes (190-120 BCE) was the first to what?
catalogue stars by their brightness
Ptolemy (140 CE) used what system?
the magnitude system.
Star Brightness has nothing to do with___
angular size rather related to intensity of light
Apparent Visual Magnitude (mv)
A measure of the brightness of a star as seen by human eyes on Earth.
Celestial Sphere
An imaginary sphere of a very large radius surrounding earth which celestial object seems to be attached to, planets, star and moon attached, model of sky
Flux
A measure of the flow of the energy out of a surface., flaux is the amount of energy crossing a unit area in a unit time, unit area perpendicular to direction of photons, flaux is how much luminous an area in a unit time (F = L/4πr^2)-measure of light from a star that hits one square meter in one second
Limitation to Magnitude Scales
- Only studies visible light not ultraviolent
- Only studies magnitude seen from earth not actual brightness since distance is not accounted for
_________ motion of sky is due to ________ movement of earth
Westward (WW)
Astronomical distance are measured in ______
degrees
Scientific Model
A concept that helps one think about some aspect of nature but is not necessarily true
NCP
Always appears at the latitudes of 0 latitude of observer, from where you are you can find north celestial depending distance of where you are, they are equal, distance= north celestial
Zenith
The in the sky directly above the observer
Nadir
The point on celestial sphere directly below the observer; opposite of zenith, has 90 degrees from plane
Circumpolar Stars
Those that never rise or set, located on the poll in line, 34 km latitude = 34 km above
celestial equator
touches the horizon @ east and west points
Where are the celestial poles located?
directly above Earth’s north and south poles
Rotation
Motion around an axis passing through a rotating body.Ex. rotation of Earth (day and night)
Revolution
Orbital motion about a point located outside the orbiting body.Ex: Revolution of Earth around the sun (yearly cycle)
what is Procession?
- Slow change in the orientation of earth axis of rotation of gravity induced
- Is a phenomena.
how long is the precession cycle?
26000 years discovered by Hipparchus.
North celestial pole locations
- near the star Thuban 4800 years ago
- closest to polaris in 2100
- near vega in 12 000 years
- near Deneb in 8,000 years
What are the Two Motions of Earth?
Daily spinning motion and precession
Earth Axis Tilt
23.4 degrees
Ecliptic
Eastward motion of sun, the projection of Earth’s orbit on celestial sphere
Angular distance
the angle between the lines extending from your eye to the two objects
Arc second
1/60th of an arc minute
Arc minute
1/60th of a degree
angular diameter
the angular distance form one edge to the other
the sun and moon are _____ in diameter
half a degree
Earth’s Bulge
Bulge in the middle, gravity of sun and moon both pull on bulge causing earth’s axis to twist upright relative to its orbit which causes earth precession and celestial poles and equator
Cycle of the Sun
Go around the continuum of a point, will point to a different constellation, if you draw a line from earth through the sun and out then the plane will move, If you draw a line from the earth through the sun it will point to a different constellation, on the first of the month
Seasons are not caused by _____________________.
variation in the distance between earth and sun
Seasons are caused by ____________________.
the amount of solar energy that Earth’s northern and southern hemispheres recieve @ different times of the year from the tip of earth’s equator and axis relative to its orbit.
(ecliptic) the apparent path of the sun around the sky
1TW = 10^12 W
Rotation of Sun
Sun appears to move west to east on celestial sphere, but from east to west is the movement
Celestial Equator
Imaginary line around the sky directly about the earth equator, located at two points, projection of earth equator on sky
What are the two point on the Celestial Equator?
Vernal Equinox (March 20 Spring Begins)Autumnal Equinox (September 22 Fall Begins)
What are the four points on the ecliptic rotation of the Sun?
- Summer Solstice (highest point)
- Winter Solstice
- Vernal Equinox
- Autumnal Equinox
vernal equinox
sun crosses celestial equator going northward
summer solstice (June 22)
sun is at its farthest north
-Sun striking the ground at a steep angle spreads out less than light striking the ground @ a shallow angle
Autumnal equinox
sun crosses the celestial equator going southward
winter solstice (Dec 21)
sun reaches its most southern point
-strikes northern latitudes at a much steeper angle and spreads out
Two Reasons For Cold Winters In the Northern Hemisphere
- Winter sunlight is more spread out as the noon winter sun is lower in the sky than in the summer
- The summer sun rises in the northeast and sets in the north west spending more than 12 hours in the sky whereas the winter sun rises in the southeast and sets in the southwest spending less than 12 hours in the sky
perihelion
earth is at its closest point to the sun (1.7 %)
aphelion
its most distant point from the sun (1.7 %)
Cycles of the moon ( 3 important points)
- The moon always keeps the same side facing the Earth.
2 .The changing shape of the moon as it passes through its cycle of phases is produced by sunlight illuminating different parts of the side of the moon as seen by an observer, due to different position of the sun and moon, results in different faces on earth, all depends on long and lat of observer - The orbital period of the moon around Earth is not the same as the length of a moon phase cycle
How much does the earth move every night?
0.5 degrees
How much does the moon move each night?
13 degrees
How far is the moon from Earth?
46 000 km
How does the moon move across sky?
- Always appear in the west, the more it changes, the more light we see from the moon, rises when the sun goes down, First half as moon grows from new to full (1-14), moon is said to wax, second half as moon shrinks from full to new, it’s said to wane. (14-28)-moves from west to east in sky
- Orbits eastward around earth
When new moon starts.
Sun and new moon are at the same point, continue separate and meet back, no moon is seen
Dark Side of the Moon
There is no ‘dark side’ of the moon, all parts of the moon experience day and night in a month long cycle.
Solar Eclipses
Sun is eclipsed (hidden) and the moon is blocking (angular sizes are the same), lasts less that 5 minutes due moon moving faster
Umbra
The region of a shadow is totally shadowed
Penumbra
Portion of a shadow that is only partially shaded
Annular
Moon crosses in front of sun but too small to fully cover, small ring still seen, not dark, if moon is in farther part of its orbit during totality, diameter will be less than diameter of sun
Lunar Eclipse
- The Darkening of the moon when it moves through the Earth’s shadows.
- The moons darkens and turns copper-red because of sunlight refracted through Earth’s atmosphere.
- Lunar Eclipses always occur at full moon but not at every full moon
Saros Cycles
An 18 year, 111/3 day period, after which the pattern of lunar and solar eclipses repeats.
Perigee
close distance in regards the moons orbit around the earth
-365.4 km
Apogee
Farthest distance of 406.7 km
Declination δ
- (degrees) the angular north
- south distance measures from the celestial equator., latitude, above equator is positive, measured from celestial equator, positive is north, negative is south, capella is half way
Right Ascension α
(Hours, minutes, seconds)
- The angular east
- west distance measured from the vernal equinox., longitude, from 0-24 hours, capella is 17 minutes
Day corresponds to
Lunar phase period
Year corresponds to
Sun rotation, one year= one full rotation
Solar Day
The average time between successive crossings of the sun on the local meridian (24 hours)
Sidereal Day
The time between successive crossings of any star on the local meridian (23 hours, 56 minutes, and 4.09 seconds)
Synodic Month
The time for a complete lunar phase (about 29.5 days)
Sidereal Month
The time for the moon to orbit Earth once relative to any star (about 27.3 days)
Tropical (Solar) Year
Time between successive spring (autumnal) equinoxes
Sidereal Year
The time for Earth to complete one full orbit around the sun relative to any star.
Apparent Solar Time
- Time measured by the location of the sun in the local sky such that
- Noon occurs when the Sun crosses the meridian-sun position relative to our local meridian
- Meridian = noon
How much does earth move every day?
1 degree
Tropical Year (DAYS)
→ 365.25 Days minus 11 minutes (due to the precession of equinoxes)
The Egyptian Concept
365 days/year
Which of the following definitions best describes a constellation?
A region of the sky containing a certain star pattern
The dividing line between the north and south celestial hemispheres
A group of very faint stars
A group of very bright stars
a region of the sky containing a certain star pattern
Which of the following best describes the Big Dipper?
An asterism
A constellation
A faint star near Polaris
The North Star
An asterism
What do stars in the same constellation have in common?
They must be part of the same cluster of stars in space
They must have been discovered at about the same time
They are in the same part of the sky as seen from the Earth
They probably formed at the same time
They are in the same part of the sky as seen from the Earth
What languages do the standard constellation names come from?
Greek and Latin
Greek and Arabic
Arabic and Sanskrit
Latin and Arabic
Greek and Arabic
Which star would appear brightest to an observer on Earth?
δ Dra 3.07
α Cet 2.53
Nim 8.07
α CMa -1.46
α CMa -1.46
What causes the precession of the Earth’s rotation axis?
The force of gravity from the Sun and Moon on the Earth’s equatorial bulge
The magnetic field of the Earth
The impacts of asteroids
The force of gravity from the Sun and Jupiter on the Earth-Moon system
The force of gravity from the Sun and Moon on the Earth’s equatorial bulge
The Earth revolves in a counter clockwise direction around the sun at about 1 deg/day (360 deg and 365 days). Then this motion makes the sun to appear moving
Not at all-the sun does not appear to move
1 deg per day westward
1 deg per day eastward
15 deg per day eastward
15 deg per day westward
1 deg per day eastward
A person in Nashville , TN observes Venus in the western part of the horizon. Six hours later Venus will be
High in the south
Low in the south
Not visible
Nearly overhead
Not visible
A person in Denver Colorado observes Jupiter in the eastern horizon right after the sunset. Where would the planet be after six hours?
Low in the west
Nearly overhead
Not visible
High in the south
Low in the south
Low in the south
Where is an observer’s nadir?
The point directly opposite the observer’s zenith
The north point on the observer’s horizon
The point directly opposite the north celestial pole
The east point on the observer’s horizon
The point directly opposite the observer’s zenith
If the apparent visual magnitude of a star is 7.3, what does this tell us about the brightness of the star?
It is not visible with the unaided eye
It appears faint because of its great distance from the Earth
It is one of the brighter stars in the sky
It is bright enough that it would be visible even during the day
It is not visible with the unaided eye
The star Vega has an apparent visual magnitude of 0.03 and the star HR 4374 has an apparent visual magnitude of 4.87. It has been determined that both stars are at the same distance from the Earth. What does this information tell us about the two stars?
Vega must produce more energy per second than HR 4374
Together the two stars would have a magnitude of 4.9Vega will appear fainter to us than HR 4374
Vega must produce less energy per second than HR 4374
Vega must produce more energy per second than HR 4374
Which of the following is equivalent to one-3,600th of a degree?
Minute of arc
Precession
Second of arc
Angular diameter
Second of arc
What is the term for the point on the celestial sphere directly above an observer, no matter where on the Earth the observer is located?
North celestial pole
Zenith
Nadir
South celestial pole
Zenith
Where is the zenith for an observer standing at a point on the Earth’s equator?
Near the horizon and towards the south
Directly overhead
Near the horizon and towards the west
The position depends on the time of day
Directly overhead
If the Earth had an orbital tilt of 0 degrees ( obliquity) then
There would not be no seasons
Day and night would be 12 long every day everywhere on the Earth
An observer at the equator would see the sun pass at zenith every day
The direct rays of the sun would shine on the equator
All of the above
All of the above
On an imaginary planet that has an orbital tilt of 32 degrees, its corresponding Tropic of Cancer can be found at the latitude of
66.5oN
32oN
23.5°N
58oN
32o N
Which of the following locations are closer to the South Celestial Pole ?
(RA= 14h Declination=+88o)
(RA= 23h Declination=2o)
(RA= 18h Declination=-66o)
(RA= 14h Declination=-88o)
(RA= 14h Declination=-88o)
Based on your computer clock lets say that today is August 31, 2015 the sun is
North on the Celestial equator moving North
South on the Celestial equator moving South
South on the Celestial equator moving North
North on the Celestial Equator moving South
North on the Celestial Equator moving South
How often is the sun at zenith for an observer at the equator?
12 times per year
Never
Twice per year
Every day
Twice per year
An observer in the northern hemisphere watches the sky for several hours. Due to the motion of the Earth, this observer notices that the stars near the north celestial pole appear to move. What pattern does this apparent movement follow?
From left to right
Counter-clockwise around the celestial pole
Clockwise around the celestial pole
From right to left
Counter-clockwise around the celestial pole
If an observer travels north, toward higher latitudes, how does the number of circumpolar stars that he or she sees in the sky change?
Also depends on the Longitude of the observer
Increases
Remains constant
Decreases
Increases
If you were standing at the Earth’s North Pole, which of the following would be located at the zenith?
The celestial equator
The nadir
The star Vega
The north celestial pole
The north celestial pole
How much of the night sky lies north of the celestial equator?
Exactly half
All of the night sky
Less than half, because of the tilt of the equator to the ecliptic plane.
More than half, because of the precession of the poles
Exactly half
Seen from Winnipeg (latitude 50 degrees North), where is the star Polaris in the sky?
50 degrees above the horizon
The position depends on the time of day
40 degrees above the horizon
Directly overhead
50 degrees above the horizon
For an observer in Pond Inlet, Nunavut, at a latitude of 73° North, what is the angle between the northern horizon and the north celestial pole?
17°
73°
23.5°
27°
73°
For an observer in Oberon Bay, Australia, at a latitude of 39° South, what is the angle between the southern horizon and the south celestial pole?
45°
23.5°
39°
51°
39°
If the north celestial pole appears on your horizon, what is your latitude?
0°
45°N
90°N
90°S
0°
Where in the sky would an observer at the Earth’s equator see the celestial equator?
The celestial equator would coincide with the horizon
The celestial equator would be directly overhead
The celestial equator would be at 45 degrees above the northern horizon
The celestial equator would be at 45 degrees above the southern horizon
The celestial equator would be directly overhead
Which of the following best defines the ecliptic?
The plane that is perpendicular to the Earth’s axis of rotation
The projection of the Earth’s equator onto the sky
The path traced out by the Sun in our sky over one year against the background stars
The path traced out by the Moon in our sky in one month against the background stars
The path traced out by the Sun in our sky over one year against the background stars
Which of the following describes a concept very similar to latitude?Question options:
Declination
Magnitude
Meridian
Right ascension
Declination
Which of the following best describes Ursa Major (the Great Bear)?
Another name for the Seven Sisters
Another name for the Big Dipper
A constellation
An asterism
A constellation
Which of the following statements correctly describes the relationship between stars and constellations?
Only those stars that were visible to the ancient Greeks are located in constellations.
Every star is located in a constellation.
Only stars close to the ecliptic (the Earth’s orbital plane) are located in constellations.
Only the brighter stars are in constellations.
Every star is located in a constellation.
Which of the following describes the magnitude scale?
It is no longer used today.
It was used to determine the rate of precession.
It originated just after the telescope was invented.
It can be used to indicate the apparent intensity of a celestial object.
It can be used to indicate the apparent intensity of a celestial object.
If the apparent visual magnitude of star A is 3.1, and the apparent visual magnitude of star B is 0.5, how do star A and star B compare in terms of apparent brightness as seen from Earth?
Star A is only slightly brighter than star B.
Star A is about the same brightness as star B.
Star A is fainter than star B.
Star A is much brighter than star B.
Star A is fainter than star B.
What aspect of an object depends on both the size of the object and the distance to the object?
Proper motion
Apparent magnitude
Apparent brightness
Angular diameter
Angular diameter
What is the term for the point on the celestial sphere directly above an observer, no matter where on the Earth the observer is located?
South celestial pole
Nadir
Zenith
North celestial pole
Zenith
Where is the zenith for an observer standing at a point on the Earth’s equator?
Near the horizon and towards the west
The position depends on the time of day
Near the horizon and towards the south
Directly overhead
Directly overhead
An observer in the northern hemisphere watches the sky for several hours. Due to the motion of the Earth, this observer notices that the stars near the north celestial pole appear to move. What pattern does this apparent movement follow?
Counter-clockwise around the celestial pole
From left to right
Clockwise around the celestial pole
From right to left
Counter-clockwise around the celestial pole
The Moon has an angular diameter of 0.5°. What is the Moon’s angular diameter in minutes of arc?
50
1800
30
0.5
50
You point your finger toward the zenith right now, and then point there again six hours later. At both times, your finger was pointing in the same direction relative to one of the options below. Which one?
Your horizon
The Sun
The ecliptic
The north celestial pole
Your horizon
For an observer in Valdivia, Chile, at a latitude of 39° South, what is the angle between the southern horizon and the south celestial pole?
45°
39°
23.5°
51°
39°
For an observer in Waterloo, at a latitude of 43° North, what is the angle between the northern horizon and the north celestial pole?
43°
23.5°
74°
36°
43°
What were the ancient Egyptians responsible for?
- Egyptians were responsible for the emergence of a 365 day calendar (around 2500 BCE)
- Our modern 24h clock partially owes its origins to the Egyptians
- Started doing math to divide land
- Luxor temple and civil ancient calendar
France 10000 BCE
- Italy: dating back to 10000 bce , there are several strange depictions in this Italian caves. It appears to depict two beings in protective suits holding strange implements. Notice the halo looking objects over their heads, which is very similar to other early cave drawings.
- Holding strange implements and halo of sun
Niaux Caves
- France what looks exactly an outline diagram of a spaceship as seen in sci-fi movies is actually a cave drawing that is found in the Niaux caves in france.
- This paleolithic cave drawn sometime between 13000 bce and 10000 bce
Stonehenge, England
- The ancient site in england may have served as an observatory completed around 1550 bce
- The sun shining through the stonehenge monument . sun rise on the summer solstice was the most important time the sun would shine through the monument
- Monoslics engraved from other meriditanian cultures
- Stones from different places
- Build it was to reflect solstis
- Aligned with seasonal motion of the sun
Bablyon
- Babylonians were some of the most meticulous record keepers
- Tablets from 2354 BCE
- Recorded detailed observations of the visible planets
- Observed and recorded a solar eclipse (763 BCE)
- En Hedu’Anna, the first female astronomer recorded in history
- Most records kept in inca, 7th century BCE map of 8 constellation, possible from asteroid
China
- Earliest known record of supernova explosion in 1400 BCE
- Another supernova explosion recorded in 1054 CE, Anasazi (New Mexico, USA) may have recorded this event as well
- The anasazi (ancient ones) thought to be ancestors of the modern Pueblo Indians in utah, colerado, new mexioco and arizona
- Inhabited the four corners country of Southern Utah, Southwestern Colorado, northwestern New Mexico and Northern Arizona
- From about AD 200 to AD 1300 leaving a heavy accumulation of house remains and debris
- Solar and lunar eclipses
Days of the week
Based on the sun, the moon and the 5 visible planets
Newgrange
Was built 5000 years ago approximately 3200 BCE, by Neolithic (stone age farming community)
Sky over Giza 2500 BC
- Pointed over orion, sirius, etc
- Could be on purpose or by accident
Sumerian star map
-Controversial, 5500 years old, reveals kofels event (mudslide), could have been due to asteroid rather than mudslide
Astronomy from 900 BCE to 0
-The greeks were among the first to develop models and serious scientific method in order to explain what they observed in the universe
Thales of Miletus
Correctly predicted a solar eclipse, predicted path, if determined saros (have to calculate from there), used math and geometry, wanted to create models
Pythagoras
Suggested the earth is a sphere not flat
Eratosthenes
Calculated earth’s circumference
Astronomy From 0 CE to 1500 CE
- Knowledge of astronomy expanded with the contributions of astronomers from greece, the middle east, and india
- Aryabhata- the Indian astronomer and mathematician, known for Aryabhatiya
Alexander the Great
Founder the city of Alexandria in Egypt
Hypatia
A female astronomer and mathematician was the director of the observatory in alexandria
Aryabhata
-The Indian astronomer and mathematician, known for Aryabhatiya
Aristotle (384 -322 BCE)
- known throughout the middle ages as “the philosopher”
- believed as a first principle that the heavens were perfect
- All motion in the perfect heaven must be caused by the rotation of the sphere carrying objects around in uniform circular motion
- Used past models to prove
Cladius Ptomely
- He gave mathematical form of aristotle’s model in about 140 CE
- He kept the geocentric (earth centered) principle, but he added off-centre circles and variable speeds to better predict the motion of planets.
- All motion in the perfect heavens must be caused by the rotation of spheres carrying objects around in uniform circular motion
- Aristotle’s Universe, as embodied in the mathematics of Ptolemy’s model, dominated ancient astronomy for almost 1500 years-challenged Aristotle’s first principle-earth a little off centered and slight vary in planet speeds challenged first principle
What was Aristotle’s first principle
Something that seems obviously true and needs no further examination., heaves are perfect
Uniform circular motion
Perfect motion of planets in a circle
Paralax
- Your view of an object changes based on the angle you look at it, and the right eye would see and object different from the left eye if you hold your thumb in the middle of the view
- Different angle depending
- Ancient didn’t observe this
Epicycles
-The small circle followed by a planet in the Ptolemaic theory. The centre of the epicycle follows a larger circle
(the deferent ) around the earth-all the planets do epicycles around themselves to orbit the earth
-2 rotations
-Large circles to study motion
-Common intersecting points
-Believed earth was slightly off centered, epicycle moved at a constant rate as seen from equant venus and mercury are different
Deferent
What the epicycle circles around
Prograde
Every planet moves from eastward, excluding one seems as if planets stops and changes direction
Retrograde in ptomelys model
From east to west venus moves this way the apparent backward motion of a planet as seen from the background of stars
Ptolemys model of the universe
- Ptolemy created an elaborate geometrical and mathematical model to explain details of the observed motions of the planets, while assuming Earth is motionless as the centre of the universe
- Ancient greek philosophers and astronomers believed that heavenly objects moved on circular paths at constant speed with earth motionless at the centre of the universe. This geocentric (earth at the centre) model was coined by Aristotle.
Nicolaus Copernicus ( 1473 -1543)
Came up with new model
Copernicus Model
- Proposed the heliocentric model of the universe
- His book De Revolutionibus orbium coelestium(on the revolutions of celestial sphere) was published after his death
- Heliocentric universe: a model of the universe with the Sun at the centre
Heliocentric model
Sun at center of universe, earth rotated on axis around sun, explained retrograde motion, earth moves faster along orbit, takes and passes the planet causing it to look like it moving backward, it’s a loop with with an angle between two orbital, could not predict position of planets so reverted back to epicycles (WRONG) all planets were treated the same unlike geocentric model (venus)
Retrograde Motion in Copernicus Model
Retrograde motion finally explained in a straightforward manner
- No need for epicycles
- This explained it
Tycho Brahe
- Danish nobleman and astronomer
- Built an impressive observatory and spent 20 years measuring the positions of the stars and planets
- Hired johannes Kepler
Keepler
- Despite being of poor health, kepler excelled in school and won entrance to the university at Tubingen
- Studied motions of planets and discovered how planets moved.
Ellipse
- A closed curve around two points, called foci
- Such that the total distance from one focus to the curve and back to the other focus remains constant
Keeplers three laws
- The orbit of planets are ellipse with the sun at one focus
- A line from a planet to the sun sweeps over equal areas in equal intervals of time, when closer to sun, planet moves more rapidly to move the same distance in the same time
- A planet’s orbital period (years) squared is equal to average distance from the sun (au) cubed, eccentricity and semi major is related
what is keeplers third law equation
P^2y = a^3au
Eccentricity
Describes the shape of an ellipse, half the distance of two foci, divided by semi- major axis
Semi-major axis
Half of the longest diameter of an ellipse
How does the orbital period change of planetary motion?
- The further the object is from an set object, the longer the period will be to go around it fully
- Area is always the same, but distance will change
Galileo
- Born in 1564 in pisa, italy. He studied medicine and later became a professor of mathematics at the university of padua
- He built working telescopes in his workshop and embarked on carefully observing the night sky
- Galileo did not invent the telescope, but was the first to observe the sky carefully. It was coined by the greek mathematician Gioavani Demisiani born in Zakynthos Greece in 1611
- Did not invent telescope
The starry messenger
- Galileo published sidereus nuncius(the starry messenger) a small book in which he reported two major discoveries
1) The moon was not perfect
2) There were four moons orbiting Jupiter(now known as the galilean moons) - Further Fundamental Discoveries
- He also discovered that venus was going through phases like those of the moonshow same face
Galileo and Rome
When Galileo visited Rome in 1611, he was treated with great respect.However, his telescopic discoveries were criticized by many. believed earth was perfectIn 1616, cardinal Bellarmine ordered him to cease public debate about models of the universeIn 1633, Galileo was condemned before the Inquisition for refusing to obey an order to halt his defense of Copernicus’s ModelIn 1992, Pope John Paul II made a formal statement acknowledging the unjust condemnation of Galileo by the Roman Catholic Churchmany rejected theory cause they couldnt understand it
Isaac Newton
- Born in the english village of Woolsthorpe
- During 1665 and 1666 newton made most of his scientific discoveries
- Newton used the work of Kepler and Galileo to discover three laws of motion and the law of gravity
- These laws made it possible to understand such phenomena as orbital motion and the tides-worked on gravity and orbits-made possible to understand phenomena of orbital motion and the tides-able to predict future movements of planets due to laws
Speed
The rate at which an object moves (changes position) by total time it takes. speed =distance/time, km/ hrs
Velocity
-Specifies both speed and direction of travel of an object
-Speed can be different but if direction is different than velocity is different
Velocity changes if:
a) speed changes
b) direction changes
c) both
Acceleration
- Is the rate of change of velocity with time. Acceleration = velocity/time
- Slowing down is negative acceleration
Motion
The speed, velocity and acceleration
Newton’s three laws of motion
- an object continues at rest or in uniform motion in a straight line unless acted upon by some force
- an object’s change in motion is proportional to the force acting on it, and is in the direction of the force
- when one body exerts a force on another body, the second body exerts an equal and opposite force back on the object
All falling objects
All falling objects on Earth have a constant acceleration of 9.8m/s^2
The universal theory of gravitation
The gravitational force of attraction between two objects depends on the product of the masses of the two objects
Inverse square relation
A rule that the strength of an effect (such as gravity) decreases in proportion as the distance squared increases
Gravitation is…..
The mutual and universal
Weight vs Mass
- Mass is NOT the same as weight
- Mass of an object is a measure of the amount of matter or “stuff” in the object.(usually expressed in kg)
- Weight is the force that gravity exerts on the object.
Orbital Motion
1) An object orbiting Earth, and any orbiting object, is actually falling (being accelerated due to gravitational force) towards Earth’s centre.
2) Objects orbiting each other actually revolve around their mutual centre of mass.
3) There is the difference between closed orbits and open orbits.
Escape velocity
The initial velocity an object needs to escape from the surface of a celestial body. ex; a orbit
Tides
- Tides are caused by small differences in gravitational force.
- Spring tide - ocean tide of large range that occurs at full and new moon
- Neap Tide - Ocean tide of small range occurring at first and third quarter moon
- Tides can also affect orbits.The moon’s orbit is growing larger by about 4 cm a year.
Shape of ellipses
e= 1, very ellongated elipsee= 0, very circular
Venus
Does not move between sun and earth. would see crescents, not observed rather rotates sun
Siderus Nuncius`
Made gallieo famous
In 1054 CE, the Chinese recorded a very interesting and powerful cosmic event. What was this event?
A star merger
A supernova
A galactic collapse
Simultaneous solar and lunar eclipses
A supernova
What did Eratosthenes measure very accurately?
The size of the Earth
The length of the year
The distance to the Moon
The length of the month
The size of the Earth
Who were the two great authorities of Greek astronomy?
Aristotle and Ptolemy
Julius Caesar and Aristotle
Columbus and Ptolemy
Alexander the Great and Julius Caesar
Aristotle and Ptolemy
Whose writings became so famous that he was known throughout the Middle East simply as “The Philosopher”?
Ptolemy
Eratosthenes
Aristotle
Hipparchus
Aristotle
Which of the following statements reflects beliefs that were almost universally held in pre-Copernican astronomy?
The planets travelled in elliptical orbits around the Earth
The planets travelled in elliptical orbits around the Sun
The Sun was at the centre of the universe
The Earth was at the centre of the universe
The Earth was at the centre of the universe
In what circumstances is retrograde motion observable?
It is observable for planets located between the Earth and the Sun
It is observable for planets more distant from the Sun than the Earth
It is only observable for the Moon
It is observable for all planets
It is observable for planets more distant from the Sun than the Earth
You are observing the night sky from Mars. In what circumstances is retrograde motion observable?
It is observable for planets more distant from the Sun than Mars
It is observable for planets located between Mars and the Sun
It is only observable for Earth and Venus
It is observable for all planets
It is observable for planets more distant from the Sun than Mars
What is the term for the apparent westward motion of a planet in the sky compared to the background stars (as viewed from the Earth) when observed on successive nights?
Epicycle
Retrograde motion
Prograde motion
Heliocentric motion
Retrograde motion
What is parallax?
The apparent motion of an object due to the motion of the observer
The observer the distance between two straight lines
The small circle that the planets slid along in Ptolemy’s geocentric universe
The distance between two foci of an ellipse
The apparent motion of an object due to the motion of the observer
Why did ancient astronomers believe that the Earth did not move?
Because they could not detect parallax
Because they believed in circular motion
Because all observable planets follow retrograde motion
Because parallax is only detectable during the day
Because they could not detect parallax
In Ptolemy’s view of the universe, what is at the centre of a planet’s epicycle?
The Sun
The Earth
The deferent
The equant
The deferent
What was the greatest inaccuracy in Copernicus’s model of the solar system?Question options:
That the planets travelled in circular orbits with uniform motion
That the planets travelled on epicycles, the centers of which followed orbits around the Sun
That the planets travelled in elliptical orbits
That the planets were allowed to travel backwards in their orbits
That the planets travelled in circular orbits with uniform motion
What was Tycho Brahe’s greatest contribution to astronomy?
His model of the universe
His telescopic observations
His discovery of three laws of motion
His 20 years of careful observations of the planets
His 20 years of careful observations of the planets
Which of the following objects cannot transit (i.e. pass in front of) the Sun, as seen from Jupiter?
Mercury
Venus
Mars
Saturn
Saturn
What two numbers tell us the size and shape of an ellipse
Radius, eccentricity
Radius, deferent
Semi-major axis, deferent
Semi-major axis, eccentricity
Semi-major axis, eccentricity
The orbit of planet A has an eccentricity of 0.5 and the orbit of planet B has an eccentricity of 0.01. What can be said about the shape of the orbits of these two planets?
Planet A has a nearly circular orbit
The orbit of planet A is more elongated than the orbit of planet B
The orbit of planet B is more elongated than the orbit of planet A
The orbit of planet A is more elongated than the orbit of planet B
There is not enough information to say anything meaningful about the shape of either orbit
Which of the following masses exert higher gravitational force on each other?
M=2——————m=2
M=2——————m=1
M=2——————m=8
M=2——————m=1
A hypothetical solar system has planets evenly spaced in circular orbits from the sun in the following distances and with the following masses, that they are given in terms with the mass of Jupiter MJ. Which of the following planets exerts the larger gravitational force of the star.
Planet A: 1 MJ 1 AU
Planet B: 3 MJ 2 AU
Planet C: 10 MJ 3 AU
Planet D: 16 MJ 4 AU
A
B
C
D
C- Planet C: 10 MJ 3 AU
Given its orbital period of 76 years, what is the average distance of Comet Halley from the Sun?
18AU
38AU
54AU
114
18AU
An object has been located orbiting the Sun at a distance of 65 AU. What is the approximate orbital period of this object?
8.1 years
65 years
524 years
4225 years
524 years
On average, Saturn is 10 AU from the Sun. What is the approximate orbital period of Saturn?
10 years
32 years
1000 years
3200 years
32 years
The orbit of the Moon is an ellipse with the Earth at one focus. What is located at the other focus?
Nothing
The asteroid belt
Comets
The Sun
Nothing
A comet is found in a highly elliptical orbit with a semi-major axis equal to one astronomical unit (AU). According to Kepler’s third law of planetary motion, what would the sidereal period of this comet be?
It would be more than one year.
It would be one year.
It would be less than one year.
It would be 76 years; the same for every comet.
It would be one year.
An object moves in a straight line at a constant speed. Which number of forces could not act on the object?
0
1
2
3
4
1
What does the orbital velocity of an object with respect to the distance does?
Stays the same
Decreases
Increases
Decreases
Would your mass and weight change if you went to the Moon?
Weight would change but mass would not
Mass would change but weight would not
Both would change
Neither would change
Weight would change but mass would not
At which lunar phase(s) are tides at their lowest?
Both new Moon and first quarter Moon
Both first quarter Moon and third quarter Moon
New Moon
Full Moon
Both first quarter Moon and third quarter Moon
If Mars rises approximately the same time as a particular star. If Mars is in normal prograde motion at what time Mars will rise next night?
Same time as the star
Earlier than the star
Later than the star
Later than the star
A planet orbits a planet in a circular orbit. How many forces are acting on the planet?
0
1
2
3
4
1
What was a common feature of astronomy as practiced worldwide prior to the Greeks?
Recognizing patterns
Making hypotheses
Defining the 24-hour clock
Observing supernovae
Recognizing patterns
What was the reason for using epicycles and deferents to explain the motion of the planets in the night sky?
Prograde motion
Mercury and Venus’s limited angular distance from the Sun
Retrograde motion
Non-uniform speed of the planets in their orbits
Retrograde motion
What is the term for a small circle that has its centre located on the circumference of another larger circle?
Equant
Deferent
Retrograde
Epicycle
Epicycle
What feature of Ptolemy’s model of the universe made it possible to explain retrograde motion?
Heliocentrism
Elliptical orbits
Epicycles
Geocentrism
Epicycles
Which of the following astronomers described the universe in a way that matches the diagram?
Kepler
Ptolemy
Copernicus
Galileo
Ptolemy
The Copernican system was no more accurate than the Ptolemaic system in predicting the positions of the planets because of a key factor that was unchanged from the Ptolemaic system. What was that factor?
The Copernican system assumed the Earth was at rest at the centre
The Copernican system used elliptical planetary orbits
The Copernican system used uniform circular motion
The Copernican system assumed all planets orbited the Sun
The Copernican system used uniform circular motion
What is the book “De Revolutionibus Orbium Coelestium” about?
It describes how Galileo’s observations and Kepler’s calculations proved the Copernican theory
It describes the construction of Galileo’s telescope and his observations
It is a dialogue written to convince the general public of the merits of the Copernican theory
It lays out the Copernican theory for the first time
It lays out the Copernican theory for the first time
What was the greatest inaccuracy in Copernicus’s model of the solar system?
That the planets travelled in circular orbits with uniform motion
That the planets travelled on epicycles, the centres of which followed orbits around the Sun
That the planets travelled in elliptical orbits
That the planets were allowed to travel backwards in their orbits
That the planets travelled in circular orbits with uniform motion
