MERCURY

Mercury is the planet closest to the Sun, and experiences scorching temperatures by day. But it has virtually no atmosphere to trap the heat, so is freezing at night. It is a rocky planet, just over a third the diameter of Earth. Its surface is covered with craters, which make it look similar to parts of the Moon. These craters were formed when the planet was bombarded with meteorites long ago.

Table 9. ESSENTIAL DATA

Diameter at equator4,880 km (3,032 miles)
Average distance from Sun57.9 million km (36 million miles)
Orbital period88 days
Rotation period58.7 days
Mass (Earth=1)0.06
Gravity (Earth=1)0.38
Average surface temperature167°C (332°F)
Number of moons0
MERCURY’S SURFACE

The craters that cover almost all of the surface of Mercury are generally shallower than those on the Moon. They vary in size from a few metres to hundreds of kilometres across. In between, there are relatively smooth lava-covered plains crossed by cliffs and ridges.

Copyright © 2007 Dorling Kindersley

stay connected

Sign up for our free email newsletters and receive the latest advice and information on all things parenting.

Enter your email address to sign up or manage your account.

Facebook icon Twitter icon Follow Us on Pinterest

editor’s picks

highlights

Top 10 Free Homework Help Websites
Is helping your child with homework more frustrating and confusing than ever before, thanks to the new Common Core standards? Check out the best free homework help websites to boost kids' success in math, science, English, and more.

Kindergarten Readiness App Wins Gold
Our Kindergarten Readiness app won the Gold Award of Excellence in the educational category at the 2014 Communicator Awards. This valuable checklist comes with games and activities to help your child practice the essential skills she needs for kindergarten. Download the Kindergarten Readiness app today!

11 Fantastic Fall Apple Desserts
Nothing says fall like the smell of an apple dessert baking in the oven. Use up your family's surplus of apples with our 11 favorite apple dessert recipes.

Find Today's Newest & Best Children's Books!
Looking for newly released books for your child? Try our new Book Finder tool to search for new books by age, type, and theme, and create reading lists for kids!