Solar System Explorer Answer Key
Explore the planets, moons, and other objects in our solar system and compare their properties.
Prior Knowledge Questions
Q1.How many planets are in our solar system?
There are 8 planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Q2.What is the difference between inner and outer planets?
Inner planets (Mercury, Venus, Earth, Mars) are rocky and small; outer planets (Jupiter, Saturn, Uranus, Neptune) are gas giants and much larger.
Q3.What keeps planets in orbit around the Sun?
Gravity from the Sun keeps planets in orbit; the planets' forward motion balances the Sun's gravitational pull.
Activity A – Planetary Comparisons
Q1.Which planet has the most moons?
Saturn has the most confirmed moons (over 140 as of recent discoveries).
Q2.Why is Pluto no longer classified as a planet?
Pluto was reclassified as a dwarf planet in 2006 because it has not cleared its orbital neighborhood of other debris.
Related Gizmos
More Earth & Space Science gizmos coming soon.