Mercury
Mercury is the smallest terrestrial planet and the planet closest to the sun. Mercury is not much larger than Earth’s moon and has no moons of its own. The interior of Mercury is probably made up mainly of the dense metal iron. The large number of craters show that Mercury's surface has changed little for billions of years.
Mercury’s Atmosphere: Mercury has virtually no atmosphere. Mercury’s high daytime temperatures cause gas particles to move very fast. Because Mercury’s mass is small, its gravity is weak. Fast-moving gas particles can easily escape into space. However, astronomers have detected small amounts of sodium and other gases around Mercury.
Mercury is a planet of extremes, with a greater temperature range than any other planet in the solar system. It is so close to the sun that during the day, the side facing the sun reaches temperatures of 430°C. Because Mercury has almost no atmosphere, at night its heat escapes into space. Then its temperature drops below -170°C.
Reading Check point:
Compare day time and nighttime temperatures on Mercury.
Mercury is the smallest terrestrial planet and the planet closest to the sun. Mercury is not much larger than Earth’s moon and has no moons of its own. The interior of Mercury is probably made up mainly of the dense metal iron. The large number of craters show that Mercury's surface has changed little for billions of years.
Mercury’s Atmosphere: Mercury has virtually no atmosphere. Mercury’s high daytime temperatures cause gas particles to move very fast. Because Mercury’s mass is small, its gravity is weak. Fast-moving gas particles can easily escape into space. However, astronomers have detected small amounts of sodium and other gases around Mercury.
Mercury is a planet of extremes, with a greater temperature range than any other planet in the solar system. It is so close to the sun that during the day, the side facing the sun reaches temperatures of 430°C. Because Mercury has almost no atmosphere, at night its heat escapes into space. Then its temperature drops below -170°C.
Reading Check point:
Compare day time and nighttime temperatures on Mercury.
