Topic 2 Flashcards
What is at the center of our solar system?
The Sun
Name the planets of the Solar System in order from closest to the Sun, to furthest
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune (My Very Easy Method Just Speeds Up Naming)
Name the dwarf planets of the Solar System in order from closest to the Sun, to furthest
Ceres (in asteroid belt), Pluto, Haumea, Makemake, Eris
What is an asteroid?
A rock greater than 10 meters in diameter. Most are in the asteroid belt between the orbits of Mars and Jupiter.
What is a comet?
Made of ice, dust, and rocky small particles. They develop a gaseous coma and tail as they sublime as they approach the Sun. Found in the Oort Cloud and Kuipler Belt .
What are Centaurs?
Celestial object which are similar to comets in composition (made of ice, dust, and rocky small particles), and similar to asteroids in size. Located between the orbits of Jupiter and Neptune.
What are Trans-Nepunian objects?
They orbit the Sun at distances greater than Neptune. They are normally found in the Kuiper Belt, Scattered Disk and Oort Cloud.
What is an astronomical unit (AU)?
The mean distance between the Earth and the Sun (150 million km)
What is the shape of an orbit?
Elliptical, not necessarily on the same plane as the Earth
What is the Zodiac band?
A band 8 degrees either side of the ecliptic and it is where all the orbits of the planets lie.
What is direct motion of planets?
When planets usually appear to move from West to East.
What is retrograde motion of planets?
When the Earth orbits near the Sun, it moves more quickly which makes other planets appear to not move at all (stationary point). Sometimes the planets appear to move backwards (retrograde).
What is the stationary point of planets?
When the Earth orbits near the Sun it moves more quickly which makes other planets appear to not move at all. This is called the stationary point.
What is the ecliptic?
The apparent motion of the Sun around the Earth
What is perihelion?
The point in which a planet is closest in its orbit to the Sun
What is aphelion?
The point in which a planet is furthest from the Sun in its orbit,
What is greatest elongation?
(tinyurl.com/earthsundiagram) Mercury and Venus are best placed for observation when they are furthest from the Sun in the sky. The positions in their orbits are known as greatest eastern elongation and greatest western elongation and at these positions, the angle between the lines planet-Earth and planet-Sun is 90°. At greatest elongation, observers on Earth can see planets half-illuminated.
What is conjunction?
(tinyurl.com/earthsundiagram) An inferior planet lies at inferior conjunction when its angle of elongation is 0°. Inferior conjunction is between the Earth and the Sun. Superior conjunction is on the other side of the Sun to the Earth.
What is opposition and why is it a good position to observe at?
(tinyurl.com/earthsundiagram) At opposition, superior planets are directly opposite the Sun in the sky and so are fully-illuminated and visible throughout the night.
What is transit?
When a planet passes in front of the solar disc while at conjunction.
What is occultation?
When an inferior planet is close to superior conjunction and it appears to disappear for a short while behind the Sun
What are 6 distinguishing features of Mercury?
1) It has no atmosphere
2) It has a temperature of 90K-700K
3) It is made of rocks and craters, similar to the Moon
4) It has a thin rock crust
5) It has a large iron core
6) It produces a small magnetic field
What are 8 distinguishing features of Venus?
1) It is geologically young
2) There is evidence of volcanic structures
3) It has a thick atmosphere
4) It spins in retrograde
5) It has an atmosphere of 96% carbon and sulphuric acid
6) It has a sunlight strength of 750K
7) It is not possible to view the surface from Earth due to 100% cloud coverage
8) It has a surface pressure 90 times that of Earth
What are 5 distinguishing factors of Earth?
1) It is covered in 71% water
2) It has an atmosphere of 78% nitrogen and 21% oxygen
3) It supports life
4) It is geologically active
5) It contains an inner and outer core which produces a magnetic field
What are 5 distinguishing factors of Mars?
1) No geological activity
2) Indications of flowing water in the past
3) Has an atmosphere of 95% carbon dioxide and 3% nitrogen
4) Its core is of a low density
5) Largest mountains and canyons in the solar system
What are 5 distinguishing factors of Jupiter?
1) It is a gas giant and so has no solid surface
2) Bands of clouds are visible
3) Has an atmosphere composed of 90% hydrogen and 10% nitrogen
4) It is the largest planet in the solar system
5) Flattened sphere due to fast rotation
What are 3 distinguishing factors of Saturn?
1) It is a gas giant
2) Extensive rings around the planet
3) Has an atmosphere made up of 96% hydrogen and 4% helium
What are 5 distinguishing factors of Uranus?
1) It is a green gas giant
2) Has a dark ring system
3) Has an atmosphere of 83% hydrogen, 15% helium and 2% methane
4) Has an inclined axis so appears to rotate on its side
5) Has a small ice-rock core
What are distinguishing factors of Neptune?
1) It is a blue gas giant
2) It has a very thin ring
3) It has an atmosphere of 79% hydrogen, 18% helium and 3% methane
4) Has a small ice-rock core
How do astronomers use unmanned space objects (probes) to gain information on different planets or celestial bodies in the solar system?
Unmanned space objects and probes can endure environments that humans cannot without the need to support life. For example, a probe can stay on Mars to collect data for longer
What could some problems be with manned exploration of our solar system?
1) Communication delays as it takes a long time for wave to travel over long distances
2) Psychological problems that arise out of isolation, confined spaces etc.
3) Radiation risks as there is no atmosphere to block or absorb harmful radiation like the Earth’s atmosphere
What are 3 ways that satellites can form?
1) A satellite forms in the same area of space as a planet eg Jupiter’s Galilean Moons
2) A satellite is captured by the Planet e.g. Phobos and Deimos of Mars, Triton of Neptune
3) A satellite evolves from the debris from an impact with the planet e.g. Earth’s Moon
Which two planet’s in our solar system do not have satellites?
Mercury and Venus
What are the names of Mars’ moons?
Phobos and Deimos
What is the name of Neptune’s moon?
Triton
What are planetary rings made of?
Rings are composed of dust, ice and rock particles quickly orbiting a planet.
What are two theories as to how planetary moons form?
some astronomers believe that it is either the shattering of a moon from the gravity of a planet or the collision of moons causing scattered debris to form around the planet.
What are three differences between cometary orbits and planetary orbits?
1) Planets don’t tend to have very eccentric orbits but comets do.
2) Comets may orbit the sun in retrograde motion unlike planets.
3) The orbits tend to be very inclined and so can always be seen.
What is the Kiupler Belt?
A disk further away from the sun than Neptune’s orbit - many comets are located in it. Short term comets orbit in this region.
What is the Oort Cloud?
A large sphere including the solar system and the Kiupler belt . Long term comets orbit the sun in this area.
What are two pieces of evidence for the existence of the Oort Cloud?
1) The comets come from all directions, not from the same plane.
2) The orbits of the comets suggest they came from around 50,000 AU away from the sun
Where on a comet is the nucleus found?
http://images.wisegeek.com/parts-of-a-comet.jpg
where on a comet is the coma found?
http://images.wisegeek.com/parts-of-a-comet.jpg
where on the comet is the dust tail found?
http://images.wisegeek.com/parts-of-a-comet.jpg
where on the comet is the ion tail found?
http://images.wisegeek.com/parts-of-a-comet.jpg
When do the tails of a comet form?
Comet materials sublime when they get close to the sub which forms a gaseous tail
When is an ion tail formed?
When solar wind hits a comet an ion tail may be formed
When is a dust tail formed?
The dust tail is formed from radiation pressure
What are meteoroids?
Objects in the sky that will turn into meteors when they make contact with the Earth’s atmosphere. Ranges up to 10m in diameter.
How are meteoroids formed?
They are formed from debris from comets and from parts of asteroids
What is a meteor?
A meteoroid that has entered the Earth’s atmosphere
What is a meteorite?
A meteor that has survived the Earth’s atmosphere and hit the surface of the Earth
What are micrometeorites?
meteorites around the size of one micrometer
What are fireballs?
large meteors that burn up when they reach the atmosphere
What are meteor showers?
Meteors come from particular parts in space leading to annual meteor showers
Where do meteors come from?
They come from comets or asteroids which reach the atmosphere
What is the radiant?
The point from which meteors appear to diverge
What are PHOs?
Potentially hazardous objects are objects that have an orbit trajectory that causes them to be within 0.05 AU of Earth. They tend to have highly eccentric orbits
Why is it important to monitor PHOs?
Inn case they collide with Earth
What are 3 examples of astronomical collisions?
1) Collisions that caused the moons craters
2) The unusual orbits of Venus and Uranus
3) The dinosaurs extinction
What did Copernicus first develop?
The heliocentric model of the solar system. This replaced Ptolemy’s geocentric model.
What did Copernicus’ model of the solar system explain?
The occasional retrograde motion of superior planets
What did Tycho contribute to our astronomical knowledge?
He obtained large amounts of information which was accurate enough for Kepler to derive his laws of planetary motion
What did Kepler contribute to our astronomical knowledge?
He derived his 3 laws of Planetary motion from Tycho’s data
What is Kepler’s first law of planetary motion?
All planets move in an ellipse with the Earth at one focus of the ellipse
What is Kepler’s second law of planetary motion?
The area that a planet covers in relation to the sun is the same for any period of time https://i.stack.imgur.com/7bnFE.gif
What is Kepler’s third law of planetary motion?
T^2 = R^3
where T is orbital period (in Earth years) and R is mean distance from sun (AU)
What are 3 astronomical discoveries that Galileo made?
1) Phases and apparent size of Venus (suggests a heliocentric model)
2) Features of the moon (it isn’t smooth)
3) The moons of Jupiter which shows that not everything orbits the Earth
How was Uranus discovered?
Herschel used a telescope and noticed a small faint disc and after subsequent observation noticed an orbit and so deduced the object as being a planet.
How was Ceres discovered?
Recently named as a dwarf planet but was first asteroid discovered. Initially discovered by Italian astronomer who then died. Mathematicians then discovered the planet after around a year with several other asteroids.
How was Neptune discovered?
Neptune’s existence was predicted by astronomers as accounting for the wobbles in the motion of Uranus which could be accounted for by the presence of another massive body. It was then observed with telescopes in the location predicted.
How was Pluto discovered?
There were further wobbles in Uranus’ orbit which caused astronomers to predict another planet affecting the orbit of Uranus which was then photographically discovered in a mathematically predicted location.
How does gravity relate to planetary orbits?
The gravitational attraction between two planets is necessary to maintain their orbit
What is the inverse square law?
The gravitational attraction between two objects is inversely proportional to the square of the distance between 2 objects
What are 3 ways astronomers can observe the existence of exoplanets?
Astrometry, the Transit Method and use of Doppler shifts
What is Astrometry?
massive exoplanets cause stars to wobble or change in position which can be precisely measured to discover the size of a planet.
What is the Transit Method?
When planets go into transit of a star the star reduces its apparent magnitude and so these changes are measured to find the size of the planets.
How do astronomers use Doppler shifts to see exoplanets?
Astronomers use red-shift and blue-shift changes to find the distance of the planets
What are the disadvantages to using Astrometry to observe exoplanets?
difficult to use due to the effects of more than one planets, small planets are not detectable, requires precise measurements that our atmosphere does not allow.
What are the disadvantages to using the Transit Method to observe exoplanets?
wobble must be in the same plane as the Earth, change in bright may be undetectable for small planets.
What are the disadvantages to using the doppler-shifts to observe exoplanets?
hift may be undetectable for small planets, planets’ orbits cannot be perpendicular to Earths’s orbit as then there would not be a distance change from Earth.
Why is the presence of water an essential requirement for life to exist?
Life as we know it requires water for processes: transport mechanism for nutrients, photosynthesis and hydrolysis (breaking down of large molecules into smaller ones). Therefore for life as we know it to exist, water is essential.
What are two theories about how water came to exist on Earth?
1) Hydrogen and oxygen from volcanoes combined to produce steam that later condensed into water
2) Water was deposited by comets which contained ice. These comets struck Earth
How did the Rosetta probe investigate the origin of water on Earth?
The Rosetta space probe landed on the nucleus of a comet to examine water content with the instrument Ptolemy. This observed the different abundances of different isotopes of water and compared them to those on Earth
What is the drake equation?
An equation that attempts to predict the existence of life elsewhere in the galaxy.
N = R* • fp • ne • fl • fi • fc • L
N = The number of civilizations in the Milky Way galaxy whose electromagnetic emissions are detectable.
R* =The rate of formation of stars suitable for the development of intelligent life.
fp = The fraction of those stars with planetary systems.
ne = The number of planets, per solar system, with an environment suitable for life.
fl = The fraction of suitable planets on which life actually appears.
fi = The fraction of life bearing planets on which intelligent life emerges.
fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space.
L = The length of time such civilizations release detectable signals into space.
What are Goldilocks zones?
Areas that are not too hot or too cold but just right. This means liquid water can exist etc.
What are habitable zones?
Placed where we look for exoplanets that are able to support life.
What are 3 ways astronomers investigate if there is life on other planets?
Radio analysis, Atmosphere spectral analysis and probes
How does radio analysis allow us to detect life on other planets?
It allows us detect signals from intelligent life
How does atmosphere spectral analysis allow us to detect life on other planets?
examined above rocky exoplanets to search for gases such as oxygen and methane which are produced by living organisms
How do probes allow us to detect life on other planets?
They are sent to planets to search for signs of present of past life
What are 3 benefits of discovering life on other planets?
1) Religion: Our beliefs in religion may dramatically change as we learn more about the universe
2) Origins of life on Earth: Aliens could give us more information about the origins of the universe.
3) Technology advancements: Aliens may have technology that can help solve many problems e.g. renewable energy.
What are 3 disadvantages of discovering life on other planets?
1) Diseases: could be brought to Earth by ET life
2) Unfriendly: aliens could wish to destroy us or may view us like how humans view animals
3) Distance: could be too far for us to travel and it would take years for us to send signals
