Questions: Planets in Our Solar System

Question 1

What is the correct order of the planets from closest to the sun to farthest?

• A. Mars, Venus, Earth, Mercury, Saturn, Jupiter, Neptune, Uranus
• B. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
• C. Earth, Mercury, Venus, Mars, Jupiter, Saturn, Neptune, Uranus
• D. Mercury, Mars, Venus, Earth, Jupiter, Neptune, Saturn, Uranus

Answer: (B)

The planets in order from closest to the sun to farthest are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. A common memory trick is 'My Very Eager Mother Just Served Us Nachos' -- the first letter of each word matches the first letter of each planet in order.

Question 2

Most eight planets in our solar system are about the same size.

• T. True
• F. False

Answer: False

The planets vary enormously in size. The four inner planets (Mercury, Venus, Earth, Mars) are relatively small and rocky. The four outer planets are much larger -- Jupiter alone is so big that over 1,300 Earths could fit inside it. Saturn, Uranus, and Neptune are also far larger than any inner planet. The size difference between the smallest planet (Mercury) and the largest (Jupiter) is vast.

Question 3

What makes Earth different from all the other planets in our solar system?

Model answer: Earth is the only known planet with liquid water on its surface, a breathable atmosphere with oxygen, and conditions that support life. It is at just the right distance from the sun -- not too hot and not too cold -- for water to exist as a liquid. No other planet in our solar system has been found to have living things.

Understanding what makes Earth special helps frame why we study other planets -- we compare them to Earth to understand what conditions are needed for life and what makes our planet unique in the solar system.