Mercury

Mysterious Planet

You can't get a clear picture of Mercury with a telescope because it is too close to the sun. A telescope wouldn't help much anyway because Mercury is so tiny. To explore the planet, you need to send a spacecraft. However, it is very difficult to get a spacecraft to Mercury. The probe has to protect itself from the heat that close to the sun, and it takes a lot of fuel to get a spacecraft to a high enough speed. NASA sent one spacecraft to fly by in the 1970's, but didn't send another probe until 2011. That latest spacecraft, called MESSENGER, is finally providing us with high-resolution photos of the entire surface.

Hollows

Scientists knew they wanted to study the craters, ridges, magnetic field, volcanoes, lava flows and more. They were also hoping they were going to discover something new, and that's what happened! Scientists call them hollows. Hollows are pits 20 to 40 meters deep with straight walls and flat floors. They are also bright around the edges. The largest ones are several kilometers wide, but the small ones are the size of houses. Because they are not filled with dust, we know they are not that old. Scientists aren't sure what causes them, but they have a guess. They think that meteorite craters may expose chemicals from under the surface that can burn up in the heat from the sun. That makes a hole just under the surface, and it collapses.

Black and White

Many of the images coming back from the MESSENGER probe are not in color. It doesn't really matter because the surface doesn't have a lot of color. Any images in natural color show a gray or tan world. Scientists do get color pictures by using false or enhanced color because it lets them see details that would be easy to miss otherwise, but it is not what you would see if you were there.