Newton learned that the orbits of the planets are the result of two actions. Describe these actions.
7. The orbits of the planets are the result of gravitation and inertia. Gravitation is the attraction of one body for another. Inertia is the tendency of a moving body to travel in a straight line unless
acted upon by an outside force.
By what criteria are planets considered either Jovian or terrestrial?
10. Size, density, composition, and rate of rotation are used to place the planets in either the Jovian or terrestrial group.
Explain why the terrestrial planets have meager atmospheres, as compared to the Jovian planets.
12. The ability of a planet to possess an atmosphere is a function of gravity. The terrestrial planets have really low masses when compared to the Jovian planets and therefore exhibit thin or no atmospheres. By contrast, the more massive Jovian planets are characterized by thick, well developed atmospheres.
Briefly outline the history of the Moon.
14. All you really need to know about the history of the moon is that about 4.5 billion years ago,
when the Earth was still in a semi molten state, an object about the size of Mars collided with the
Earth and knocked off enough debris that eventually coalesced into the moon.
Venus was once referred to as "Earth's twin". How are these two planets similar? How do they differ?
16. Earth and Venus are similar in terms of their size, density, and composition. However, Venus has much higher surface temperatures as well as very high surface pressures due to a substantial
atmosphere of mainly carbon dioxide. Venus lacks the surface water found on Earth and while
both planets display extensive volcanic activity, the volcanoes on Venus tend to be shorter and
What surface features do Mars and Earth have in common?
17. The surface features that Mars has in common with Earth are volcanoes, sand dunes, and large canyons.
Why might astrobiologists be intrigued by evidence that groundwater has seeped onto the surface of Mars?
19. Astrobiologists are excited about evidence that groundwater has seeped onto the surface of Mars because water is an essential ingredient life.
What is the nature of Jupiter's Great Red Spot?
20. Jupiter's Great Red Spot apparently is a counterclockwise-rotating storm.
Why are the Galilean satellites of Jupiter so named?
21. The moons were named by Galileo, who first observed them telescopically in the early 1600s.
What is distinctive about Jupiter's satellite, Io?
22. Io has been observed to be volcanically active.
Why are many of Jupiter's' small satellites thought to have been captured?
23. The small size and retrograde motion of the four outer satellites of Jupiter indicate that they were captured.
How are Jupiter and Saturn similar?
24. Jupiter and Saturn are similar in that they are both large Jovian planets with numerous satellites; both have ring systems, although Saturn's rings are much more pronounced; and both have dynamic atmospheres with cyclonic storms on their surfaces.
Name three bodies in the solar system that exhibit active volcanism.
27. Earth, Jupiter's moon Io, and Neptune's moon Triton are known to have active volcaniclike
Where are most asteroids found?
28. Most asteroids lie between the orbits of Mars and Jupiter.
What do you think would happen if Earth passed through the tail of a comet?
29. The event would most likely be associated with meteoroid showers.
Compare meteoroid, meteor, meteorite.
31. Meteoroid is the name given to any extraterrestrial particle that enters Earth's atmosphere, generally burning to produce a streak of light called a meteor. On occasions when meteoroids reach Earth's surface, the remains are termed meteorites.
Why are impact craters more common on the Moon than on Earth, even though the Moon is a much smaller target and has a weaker gravitational field?
33.1) Meteorite craters are more common on the Moon because erosion has removed most of them
from Earth's surface.
2) There was more debris in the early solar system colliding with the various bodies. Since the
moon solidified before the Earth, these early collisions left craters on the moon, but not on the
3) Earth's atmosphere burns up much of the debris before it can hit the Earth.
4) Vegetation has grown over some craters.
5) Craters may be under the ocean were we cannot see them or they have already been removed by the action of the ocean.