The first planet
Temperatures on Mercury's surface can reach 800 degrees Fahrenheit (430
degrees Celsius). Because the planet has no atmosphere to retain that heat,
nighttime temperatures on the surface can drop to -280 degrees Fahrenheit (-170
degrees Celsius).
Because Mercury is so close to the sun, it is hard to directly observe from
Earth except during twilight.
No Atmosphere
Rather than an atmosphere, Mercury possesses a thin
exosphere made up of atoms blasted off its surface by solar
wind and striking micro meteoroids. Because of the planet's extreme surface
temperature, the atoms quickly escape into space. With the thin exosphere, there
has been no wind erosion of the surface and meteorites do not burn up due to
friction as they do in other planetary atmospheres.
Mercury is the second smallest planet in the solar system, larger than
Pluto which is now not a member of the solar system. Mercury is the second densest planet
after Earth, with a large iron core having a radius of 1,100 to 1,200 miles
(1,800 to 1,900 kilometers), about 75 percent of the planet's radius. Mercury's
outer shell, comparable to Earth's outer shell (called the mantle), is only 300
to 400 m to 600 m thick
degrees Celsius). Because the planet has no atmosphere to retain that heat,
nighttime temperatures on the surface can drop to -280 degrees Fahrenheit (-170
degrees Celsius).
Because Mercury is so close to the sun, it is hard to directly observe from
Earth except during twilight.
No Atmosphere
Rather than an atmosphere, Mercury possesses a thin
exosphere made up of atoms blasted off its surface by solar
wind and striking micro meteoroids. Because of the planet's extreme surface
temperature, the atoms quickly escape into space. With the thin exosphere, there
has been no wind erosion of the surface and meteorites do not burn up due to
friction as they do in other planetary atmospheres.
Mercury is the second smallest planet in the solar system, larger than
Pluto which is now not a member of the solar system. Mercury is the second densest planet
after Earth, with a large iron core having a radius of 1,100 to 1,200 miles
(1,800 to 1,900 kilometers), about 75 percent of the planet's radius. Mercury's
outer shell, comparable to Earth's outer shell (called the mantle), is only 300
to 400 m to 600 m thick