12 facts about the closest planet to the Sun.
Image credit: NASA
1. Mercury speeds around the sun every 88 Earth days, traveling through space at nearly 31 miles (50 kilometers) per second. Faster than any other planet.
2. The ancient Romans named it Mercury in honor of the swift messenger of their gods.
3. Mercury is only 3,031 miles (4,878 kilometers) across and is not much larger than our moon.
4. The planet rotates once about every 59 Earth days. As a result of the planet’s slow rotation on its axis and rapid movement around the sun, a day on Mercury lasts 176 Earth days (interval between one sunrise and the next).
5. Mercury travels around the sun in an elliptical (oval-shaped) orbit. The planet is about 28,580,000 miles (46,000,000 kilometers) from the Sun at its closest point, and about 43,380,000 miles (69,820,000 kilometers) from the Sun at its farthest point.
6. The temperature on Mercury may reach 840 degrees F (450 degrees C) during the day. But at night, the temperature may drop as low as -275 degrees F (-170 degrees C).
7. Due to Mercury’s proximity to the Sun, the very thin atmosphere is blasted off its surface by the solar wind and quickly escapes into space. Mercury’s atmosphere is constantly being replenished.
8. Because of the lack of atmosphere, Mercury’s sky is black. Stars probably would be visible from the surface during the day.
9. The surface of Mercury consists of cratered terrain and smooth plains and many deep craters similar to those on the moon. The largest known crater is Caloris Basin, with a diameter of 1300 km (800 miles).
Image credit: NASA
10. Scans of Mercury made by Earth-based radar indicate that craters at Mercury’s poles contain water ice. The floors of the craters are permanently shielded from sunlight, so the temperature never gets high enough to melt the ice.
11. Because Mercury is so close to the sun, it is hard to directly observe from Earth except during twilight. Mercury makes an appearance indirectly, however, 13 times each century.
12. Mercury has been suggested as one possible target for space colonization of the inner solar system, along with Mars, Venus, the Moon and the asteroid belt. Permanent colonies would almost certainly be restricted to the polar regions due to the extreme daytime temperatures elsewhere on the planet, although excursions to the other parts of the planet would be feasible with appropriate measures