| The Milky Way is one of billions of galaxies in the ____. |
Galileo Galilei |
| ____ is the hottest planet due to a runaway greenhouse effect. |
Mercury |
| Polaris is commonly known as the ____. |
North Star |
| The largest of Saturn's moons is ____. |
Pluto |
| Unlike the other planets, ____ has no substantial atmosphere. |
Sun |
| The Moon is three times larger than ____. |
Titan |
| Jupiter's four largest moons were discovered by ____ in 1610. |
Universe |
| The ____ is about a hundred times larger than the Earth. |
Venus |
