A planet is a nearly spherical body which is in orbit around the Sun. Our Sun is a star which is many times bigger than all of the planets. A solar system is a star and all of its planets, asteroids, comets and other bodies. It is significantly bigger than a star.

Weight or Force due to gravity is simply the mass (m) times acceleration due to gravity (g). F=mg. If you use kg for mass and 9.81 m/s^2 for acceleration due to gravity on earth, your answer will be in Newton’s. (60kg)(9.81m/s^2) = 588.6 N.

Tough Place to Live No evidence for life has been found on Mercury. Daytime Temperatures can reach 430 degrees Celsius (800 degrees Fahrenheit) and drop to -180 degrees Celsius (-290 degrees Fahrenheit) at night. It is unlikely life (as we know it) could survive on this planet.

Although the Sun looks small from Earth, it is really much, much bigger than our planet (and any other planet in the solar system)….Big, Bigger, Biggest.

Is Earth the Fifth Smallest Planet?

• Mercury (Average diameter: 4879.4 km, or about 2/5 the size of Earth)
• Mars (Average diameter: 6772 km, or about 1/2 the size of Earth)
• Venus (Average diameter: 12,104 km, or about 9/10 the size of Earth)
• Earth (Average diameter: 12,735 km)
• Neptune (Average diameter: 49,105 km, or about 3.8 times the size of Earth)

To ensure that the list stays stuck, just think of something along the lines of “Mercury Met Venus Every Night Until Saturn Jumped.” Essentially, this indicates that the size of the planets in order from smallest to largest is Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn, and Jupiter.