How the Universe Works – Planets
Astronomy
Name:
Date:
1. How many planets are in the Milky Way Galaxy?
2. There are __________ rocky planets in the inner solar system and in the outer solar system there are
______________ giant gas planets.
3. How long ago was our solar system born?
4. Close in where it’s hot, the sun burns off _______________ and boils away water. Only materials
that stay ____________ at high temperatures can survive, which is why _______________ planets
survive close to the sun.
5. Is it possible to have a solar system with no terrestrial planets?
6. Describe accretion.
7. For a growing planet to become round, it has to become _________________ miles across. Then it
has enough gravity to crush it into a sphere.
8. 4.5 billion years ago, about _________________ baby planets circled our sun.
9. Mercury is tiny, bleak, and super _______________...the result of a monster collision.
10. Sometime late in its development, the Earth was impacted by another object which created debris that
re-accumulated to form what is the ________________.
11. All four inner planets have a solid ______________ core and an outer surface crust.
12. A super hot ejection of particles form the sun is called a solar _________________.
13. Why isn’t energy from the sun a threat to earth?
14. When solar wind interacts with our magnetic field, it produces big light shows called
_____________________.
15. Today Mars is cold and dry with little ______________________.
16. Why is it believed that Mars no longer has a magnetic field?
17. The gas giants formed in a portion of the solar system that was ________________ so gas was able to
form ice.
18. Jupiter and Saturn have over ________________ moons each.
19. Why can’t material from Saturn’s rings gather into large moons?
20. What goes on inside all gas giants is a ___________________.
21. Jupiter has winds of about ________________ miles per hour.
22. Auroras on Jupiter and Saturn are proof that Gas Giants have ____________ ____________, too.
23. Why will we probably never really figure out what’s at Jupiter’s core?
24. Most likely, the core of Jupiter is made up of liquid, __________________, hydrogen.
25. Earth by mass is only _______________ percent water.
26. The moons of Jupiter, Saturn, Uranus, and Neptune are at least _______________ percent water.
27. Where do scientists think we got our water from?
28. Scientists have discovered more than ___________________ new planets, but none like ours.
Video Summary:
29. List two things you learned from this video that you didn’t know before today (at least one of them
has to NOT be a question on this worksheet!)
30. List one question you still have about solar systems.
31. Do you think there is water on other planets? Life on other planets? Life like ours? Why/why not?