Astronomy Final Exam Review
Part 1
1. The Big Bang Theory – huge explosion that began the universe
a. What is it (4 events)
Step 1: All matter and energy in the universe was once located in a single
dense point called a singularity.
Step 2: A HUGE explosion occurred!
Step 3: Matter and energy were propelled outward in all directions as the
universe began to expand.
Step 4: Matter began to condense - forming galaxies and these galaxies
continue to move outward today
b. What are the two pieces of evidence for it
Red shift and cosmic microwave background radiation
Red shift – objects are moving away from each other in space (moving toward
the red)
Cosmic Background Radiation – energy left over from the Big Bang
2. Be able to explain the speed with which objects are moving away from us and
each other
The farther objects are from each other the faster they move away from each
other (look in your notes at the balloon analogy and the raisin bread analogy)
3. What is a galaxy and what does it consist of?
3. An immense and relatively isolate cloud of hundreds of millions to hundreds of
billions of stars. Each star moves in its own orbit guided by the gravity generated
by other
4. Describe the three main shapes of galaxies and which are more abundant.
The three main shapes are elliptical (oval or egg shaped), spiral (two or more
arms winding out from the center) and irregular (neither arms or uniform
appearance). Elliptical is most abundant
5. Describe the two other type of galaxies Hubble discovered
Barred Spirals (arms emerge from the ends of a central elongated region) and SO
galaxies (disk systems with no evidence of arms)
6. Explain galaxy rotation
Spirals rotate faster than ellipticals
7. What is a star burst galaxy?
Galaxies where there are many dust and gas clouds colliding to form stars. These
are the most luminous galaxies
8. What is a ring galaxy?
A smaller galaxy orbiting around a spiral galaxy
9. What is galactic cannibalism and what is the resulting galaxy like?
Small galaxies are captured by larger galaxies usually resulting in an irregular
shaped galaxy
10. What is an active galaxy?
Centers (nuclei) emit abnormally large amounts of energy from a tiny region in
their core
11. What are the three types of active galaxies and what are the causes for them?
Radio galaxies – emit large amounts of radio energy
Seyfert Galaxies – abnormally luminous nucleus, contains clouds moving at high
speeds.
Quasars – very far away and very luminous (1000X more than the milky way).
Can be like a radio or seyfert galaxy
12. What is a galaxy cluster and how can they be rich or poor?
Groups of galaxies held together by gravitational force. Rich galaxy clusters are
large and have many galaxies in them with a large gravitational pull. Poor galaxy
cluster have only a dozen galaxies in them.
13. What is a supercluster
A group of galaxy clusters may gravitationally attract each other into a larger
structure called a supercluster – a cluster of clusters
14. What are the three categories of stars and their relative sizes?
Sun-sized stars (up to 6 times the size of the sun)
Huge stars (6 - 30 times the size of the sun)
Giant Stars (over 30 times the size of the sun)
15. What is the name of our galaxy? Milky Way
16. Explain the structure of our galaxy. Disk, halo and bulge
17. What is dark matter
material that emits no radiation (at any wavelength)
18. How many stars are in our galaxy
100 billion stars
19. What is interstellar matter
The space between stars is not empty: it contains interstellar matter composed
of gas and dust
20. What is a nebula?
A ball of gas and dust that has the possibilities of becoming a star
21. What is nuclear fusion
changing Hydrogen molecules into Helium molecules to create heat and light.
Also called thermonuclear fusion
22. Explain the death of a sun-sized star using the terms: red giant, white dwarf and
black dwarf.
Once their fuel is used up, the core shrinks and the outer layers begin to expand
forming a red giant.
Eventually, the star loses enough mass that it becomes a white dwarf.
White dwarfs continue to lose heat and eventually become black dwarfs.
23. Explain the death of a huge star using the terms: super red giant, supernova and
neutron star.
Once their fuel is used up, the core shrinks and the outer layers begin to expand
forming a super red giant.
Eventually, the star’s core collapses so much that it explodes in a supernova.
This size star will eventually become a neutron star - a star that has about 1.5
times the mass of our sun, but only about 10 km in diameter.
24. Explain the death of a giant star using the terms: super red giant, supernova and
black hole
Once their fuel is used up, the core shrinks and the outer layers begin to expand
forming a super red giant.
Eventually, the star’s core collapses so much that it explodes in a supernova.
This size star will collapse on itself so much that it’s gravity takes over
completely and not even light can escape. It becomes a black hole.
25. What is a black hole?
When a star collapses on itself so much that it’s gravity takes over completely and
not even light can escape
26. What is a supernova remnant
The huge, glowing cloud of debris that expands from a supernova explosion
sweeping up interstellar material as it goes Supernova remnants have a more
ragged look compared to planetary and other nebulas
27. Explain how color of a star relates to temperature
The bluer the star the hotter the temperature and the redder the star the cooler the
temperature
28. What is apparent brightness or magnitude
the brightness of a star as it appears from Earth.
29. What is absolute brightness or magnitude
is how bright a star really is. The absolute brightness is a characteristic of the star
and is not dependent on its distance from Earth.
30. Be able to answer questions using the HR diagram
31. What color are the hottest stars and what color are the coolest?
Blue is hottest and red is coolest
32. What is a main sequence star?
major grouping of stars that forms a narrow band from the upper left to the lower
right when plotted according to luminosity and surface temperature on the
Hertzsprung-Russell diagram
33. What is a solar system
The Solar System is occupied by a variety of objects, all maintaining order
around the sun
34. What is the age of the solar system and how do we know?
Radioactive dating of rocks from the Earth, Moon, and some asteroids suggests an
age of about 4.5 billion yrs
35. What is the solar nebula hypothesis
Solar System evolved from a rotating, flattened disk of gas and dust (an
interstellar cloud), the outer part of the disk becoming the planets and the inner
part becoming the Sun
This hypothesis naturally explains the Solar System’s flatness and the common
direction of motion of the planets around the Sun
Astronomy Review Sheet
Part 2
36. What is a solar nebula?
A few million years passes for a cloud to collapse into a rotating disk with a bulge
in the center. This disk is called the solar nebula with the bulge becoming the
Sun and the disk condensing into planets
37. What is a planetesimal and how does it form into a planet?
Next step is for tiny particles to stick together into bigger pieces through
collisions As long as collision are not too violent, objects, called planetesimals,
ranging in size from millimeters to kilometers, may formP
Planets formed from
“gentle” collisions of the planetesimals, which dominated over more violent
shattering collisions
38. Explain how the gas giant planets were formed.
It is possible the outer regions of the solar nebula were cold and dense enough for
gravity to pull gas together into the giant planets without the need to first form
cores from planetesimals
39. How were moons formed?
Moons of the outer planets were probably formed from planetesimals orbiting the
growing planets
40. How were the atmospheres of the planets formed? Be sure to state the difference
between the inner and outer planets atmosphere formation.
Atmospheres were the last planet-forming process
Outer planets gravitationally captured their atmospheres from the solar nebula
Inner planets created their atmospheres by volcanic activity and perhaps from
comets and asteroids that vaporized on impact
41. What did the solar wind do for the solar system?
Residual gas and dust swept out of the Solar System by young Sun’s intense solar
wind
42. What kind of star is the sun?
The Sun is a star, a ball of incandescent gas whose output is generated by nuclear
fusion in its core
43. What gases make up the sun? helium and hydrogen are the most abundant
44. What is the size of the sun? 700 times the mass of the rest of the solar system
together
45. Describe the orbit of each planet and explain the differences in rotation and
revolution of the planets.
Orbits are elliptical, lying in nearly the same plane – Pluto is the exception with a
high (17°)) inclination of its orbit
All the planets travel (revolve) counterclockwise around the Sun
Six planets rotate counterclockwise; Venus rotates clockwise, and Uranus and
Pluto appear to rotate on their sides
46. Name the nine planets and explain the differences between the inner and outer
planets. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.
The inner planets are smaller and terrestrial and have a rocky land mass, the outer
planets are larger(except for Pluto) and they are gaseous, liquid or icy.
47. What is a satellite?
Anything that orbits a planet(moons)The moons generally follow approximately
circular orbits that are roughly in the planet’s equatorial plane, thus resembling
miniature solar systems
48. What are asteroids and where are they located?
Asteroids are rocky or metallic bodies ranging in size from a few meters to 1000
km across (about 1/10 the Earth’s diameter)
Most asteroids are in asteroid belt between Mars and Jupiter indicating that these
asteroids are the failed building-blocks of a planet
49. What is a comet and what does it orbit?
Comets are icy bodies about 10 km or less across that can grow very long tails of
gas and dust as they near the Sun and are vaporized by its heat comets orbit the
sun
50. What two planets have no satellites?
Mars and Venus
51. Describe the atmosphere, temperature and surface structures for the following:
Mercury – not atmosphere (too close to sun) high 800 F low –280 F
Venus – 96% CO2, extremely dense, 900 F due to greenhouse effect
Earth – 78% N, 21% O, temperatures vary seasonally and latitudinally
Mars – 95% CO2, low density and distance from sun make temps very cold
Mercury - circular craters cover the surface
Venus –less mountainous and rugged than Earth, low gently rolling plains
Earth – mountains, plains, ocean, polar ice caps
Mars – large rift running along the equator of the planet and polar ice caps
52. Describe the satellites of Earth and Mars.
Earth has one satellite and Mars has two satellites
53. Describe the three expeditions to explore Mars.
Mars Pathfinder/Sojourner landed in 1997
Pathfinder studied the atmosphere and noticed wispy cirrus clouds like those on
Earth and large variations in surface temperature even over distances as small as 1
meter
Sojourner, a small motorized cart, examined rocks and found some indications
that the landing site was once covered by water
Mars Global Surveyor In Orbit in 1997
Detailed images show evidence of soil and rock layers as well as many windcaused erosion features
Mars Rovers Launched June 2003 and arrived on Mars January 2004
The rovers were designed to last for 90 days on the Martian surface.
The rovers investigate the landscape and collect samples, sending data back to
scientists on Earth.
54. What are the gases that the outer planets are composed of? Hydrogen and helium
55. Describe the atmosphere composition, color, size and satellites of the following:
Jupiter – dense, parallel cloud bands, mainly H and He, convection pattern for
heating atmosphere, comes from high core temp
Saturn – low density atmosphere, mostly H, cold enough for ammonia gas to
freeze into clouds
Uranus – blue, atmosphere rich in hydrogen and methane, very cold due to
distance from sun
Neptune – thin atmosphere rich in H and methane, cloud bands and vortexes
Pluto – not gaseous, water, ice and rock
Moons – Jupiter (Io, Europa, Ganymede, Callisto) Saturn (Titan), Uranus
(Miranda), Neptune (Triton), Pluto (Charon)
56. Explain the differences in ring composition of the four Jovian planets.
Rings
Composition – water, ice and carbon particles
Locations – Jupiter, Saturn, Uranus, Neptune and Pluto
Origins – left over remains from planet formation, which must be replenished
57. Explain why Pluto is not considered a planet because of its orbit.
Differences from other planets – not gaseous, more circular orbit, orbit lies out of
plane of other planets, extremely small
Composition – water, ice and rock
58. How was Neptune discovered?
It was discovered because it interrupted Uranus’ orbit.