Mercury
Did You Know?
Mercury is the smallest planet in our Solar System!
The Closest Planet to the Sun
Mercury is the smallest planet in our Solar System and the closest to the Sun. It's a rocky planet with a heavily cratered surface, similar to Earth's Moon. Despite being closest to the Sun, Mercury is not the hottest planet - that title belongs to Venus due to its thick atmosphere. Mercury has no atmosphere to retain heat, so temperatures swing dramatically between day and night.
Extreme Conditions
Mercury experiences the most extreme temperature variations in the Solar System. During the day, surface temperatures can reach 427°C (800°F), hot enough to melt lead. At night, temperatures drop to -173°C (-280°F). This 600-degree temperature swing happens because Mercury has no atmosphere to trap heat. The planet's slow rotation also contributes to these extremes.
Surface Features
Mercury's surface is covered with craters from billions of years of asteroid and comet impacts. The largest crater, Caloris Basin, is 1,550 kilometers (960 miles) across. The planet also has cliffs called 'scarps' that formed as Mercury's interior cooled and contracted. These features tell us about the planet's geological history.
Amazing Facts
Mercury completes an orbit in 88 Earth days
This fact reveals the incredible scale and wonder of our universe.
Click to flip back
Mercury is only slightly larger than Earth's Moon
This fact reveals the incredible scale and wonder of our universe.
Click to flip back
Mercury has a large iron core
This fact reveals the incredible scale and wonder of our universe.
Click to flip back
Only two spacecraft have visited Mercury
This fact reveals the incredible scale and wonder of our universe.
Click to flip back