Mercury's Symbol

Mercury: Planet Closest to the Sun

Shuttle

Boy floating in spacesuit

Guess what?

Due to Mercury's rotation and highly elliptical orbit, the Sun appears to rise briefly, set, and rise again before it travels westward across the sky. At sunset, the Sun appears to set, rise again briefly, and then set again.

Mercury is only about one-third the size of the Earth. It is smaller than any other planet. Mercury is very close to the Sun and has no substantial atmosphere. These factors contribute to the fact that the surface of Mercury has the greatest temperature range of any planet or natural satellite in our solar system. The surface temperature on the side of Mercury closest to the Sun reaches 427 degrees Celsius, a temperature hot enough to melt tin. On the side facing away from the Sun, or the night side, the temperature drops to -183 degrees Celsius. Scientists have detected a magnetic field surrounding Mercury, though it is not as strong as the field around the Earth. Scientists theorize that Mercury's field is due to an iron-bearing core or possibly to the solar winds. Mercury's atmosphere is very thin and is composed of helium and sodium. The surface of Mercury has been shaped by three processes: impact cratering where large objects struck the surface resulting in crater formation, volcanism where lava flooded the surface, and tectonic activity where the planet's crust moved in order to adjust to the planetary cooling and contracting. Mercury does not have any naturally occurring satellites.

Mercury

Mercury

A Question

What is the difference in the temperature of Mercury's surface when it is facing towards and away from the Sun?

Boy holding satellite

The Facts
The Facts

Did you know?
Did You Know?

The Answer
The Answer

Shuttle

Show me the Level 1 version of this page.

The StarChild site is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA/ GSFC.

StarChild Authors: The StarChild Team
StarChild Graphics & Music: Acknowledgments
StarChild Project Leader: Dr. Laura A. Whitlock
Curator:Meredith Gibb
Responsible NASA Official: Phil Newman
If you have comments or questions about the StarChild site, please send them to us.