Fifth Grade
Worksheets
Mercury, the Speedy Planet
Photo credit: NASA. Comparing the size of the four inner planets, from left to right: Mercury, Venus, Earth, and Mars.
Mercury is our smallest planet. It is a little larger than Earth's moon and only about one-third the size of Earth. Mercury's smaller size means it has less gravity than Earth does. If you weigh one hundred pounds on Earth, you would only weigh thirty-eight pounds on Mercury.
Each planet moves around the sun in a path called an orbit. The time it takes a planet to make one orbit or revolution around the sun is called a year. Earth makes one orbit in about 365 days, a year on Earth. Mercury's year is only 88 days. Mercury is the speediest planet, orbiting at a speed of about 106,000 mph! Mercury was named for a Roman god. The Roman god Mercury was a speedy messenger, usually depicted with a winged hat and wearing sandals with wings so he could fly. Because the planet Mercury crossed the night sky so quickly, it was given this name.
