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Astronomy 2 Study Guide – Solar System
Review Vocabulary, Notes, Worksheets, Activities and CERs.
1. What two factors affect gravity? mass and distance
2. Which factor has a greater effect? distance
3. a. What is the difference between rotation and revolution? Rotation is spinning on an axis, while
revolution is traveling around/orbiting the star.
b. Which determines a day?_rotation_A Year?__revolution__
4. a. What is retrograde rotation? When a planet spins “backwards” - clockwise
b. Which planet has retrograde rotation? Venus
5. Inner planets are also called the terrestrial planets because they are small and rocky.
6. List the 4 inner planets in order giving a brief description of each:
**see Planet Fact Chart and Inner Planets WS
Mercury –smallest, closest to Sun
Venus – “Earth’s twin”, retrograde rotation, thick atmosphere, day is longer than year
Earth – has life
Mars – red due to iron oxide, little atmosphere
7. Outer Planets are also called the gas giants or Jovian planets because they are large
and made of chemicals that are gasses on earth. They have more gravity because they
have more mass which causes them to have rings and many moons orbiting them.
8. List the 4 outer planets in order giving a brief description of each:
**see Planet Fact Chart and Outer Planets WS
Jupiter – largest planet, most gravity
Saturn – outer planet, many rings
Uranus – rotates on its side
Neptune – farthest planet from Sun
9. Which planets do not have moons? Mercury & Venus
10. Which is Earth’s twin & why? Venus – similar size, mass, density
11. Which planets have rings? Outer planets (Jupiter, Saturn, Uranus and Neptune)
12. Why do we have different weights on other planets? Different planets have different masses and
therefore different amounts of gravity which determines weight.
13. What is the Earth’s natural satellite? The moon
14. When a planet is tilted on its axis it will experience seasons.
15. What is odd about the axis of Uranus? It is sideways (tilted 90°)
16. Planets must meet these criteria: revolves in a stable orbit around the Sun; must be large enough
that its own gravity pulls it into a round shape, and it must be dominant enough to clear the area
around it
17. a. Inferior planets show phases because they are closer to the sun than the Earth.
b. Superior planets are always full because they are farther away from the sun than Earth.
c. Which inner planet is also superior? Mars
18. Dwarf Planets are very similar to planets except that they are not alone in their orbits like a planet
19. Asteroids are similar to dwarf planets except that asteroids are irregular shaped while dwarf planet
are spherical
20. Comets usually come from the Kuiper Belt or Oort Cloud and are only visible when they approach
the Sun.
21. Meteors are often called shooting starts. Describe what a shooting star actually is:
When an object from space (meteoroid) burns as it passes through the Earth’s atmosphere
22. a. What feature is found between the inner and outer planets? asteriod belt
b. Which dwarf planet is found there? Ceres
Neptune
24. Draw in the Asteroid belt, Kuiper Belt, Pluto, Ceres, Oort cloud and Sedna on the image above.
25. What unit do we use to measure distance within our solar system? Astronomical units (AU)
Oort
Cloud
Uranus
Sedna
Saturn
Kuiper
Belt
Jupiter
Pluto
Mercury Venus Earth Mars
Asteroid Belt Jupiter
Saturn Uranus Neptune Kuiper
Belt Oort Cloud
Asteroid Belt, Ceres
23. Label the planets below:
26. List and briefly explain Kepler’s Laws of planetary motion. You may draw a diagram.
1st Law – Planets orbit the Sun in elliptical orbits
2nd Law – Planets travel at different speeds in different parts of their orbits, however, an imaginary
line between the Sun and the planet will sweep out the same area over the same amount of time.
3rd Law – A planet’s period is related to its distance from the Sun – a planet located farther from the
Sun will have a longer period.
27. When Earth is closest to the Sun it is called perihelion, when Earth is farthest from the Sun, it is
called aphelion.