Mercury - how hot is Mercury? what will happen to Mercury when our Sun becomes a white dwarf? answers questions
Upgrade /Log in
Options /Log out
Early Europe
Central Asia
Islamic Empire
Native Americans
S./Central America
American History


Mercury from space
Mercury from space

Mercury is the closest planet to our Sun. At some parts of its orbit, Mercury is only about 46 million kilometers away from the sun. Because Mercury is so close to the sun, it is very hot there. It is so hot that all the carbon dioxide and oxygen has boiled away, and Mercury has very little air. On Mercury, it's so hot that even some metals like tin melt into liquids, as if they were water. It's about 427 degrees Celsius - more than four times as hot as boiling water.

Venus and Mercury at dawn
Venus and Mercury at dawn - Mercury is the one higher up

Mercury is a small planet. It is only about one-third the size of Earth. Mercury never gets closer than about 77.3 million kilometers from Earth. Even though it is so small and far away, you can see it from Earth without using a telescope, if you look just at sunset or sunrise.

Because Mercury is so close to the Sun, it doesn't take very long to go around the Sun. It goes around once every 88 days, so a year on Mercury is only about three months long.

Like the Earth, Mercury's center is mostly made of iron, with a layer of silica rocks on top of that.

Nobody from Earth has ever been to Mercury, but in 1975 we did send a spaceship there, which took pictures and sent them back to us. Another spaceship reached Mercury in 2011, and sent better pictures back.

Bibliography and further reading about planets:

Physics home

Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

Help support! (formerly "History for Kids") is entirely supported by your generous donations and by our sponsors. Most donors give about $10. Can you give $10 today to keep this site running? Or give $50 to sponsor a page?

'Tis the season: read all about the history of Thanksgiving, Hanukkah, and Christmas. Who invented Christmas trees? Who were the Maccabees? When was Jesus really born? How did people celebrate Hanukkah in the Middle Ages? Plus, some great gift ideas.