Mercury
17 questions tagged Mercury — spanning every one of the seven Ws.
Why does Mercury have almost no atmosphere?
Mercury is small, hot and close to the Sun, so its weak gravity can't hold onto gases, which are blasted away by heat and the solar wind.
Why is Mercury so heavily cratered?
Mercury has almost no atmosphere, so rocks from space do not burn up before hitting the surface. Its old, inactive crust has preserved impact scars for billions of years.
When was the first spacecraft to visit Mercury?
Mariner 10 first flew by Mercury on 29 March 1974. It was the first spacecraft to observe Mercury up close.
When was the first spacecraft to reach Mercury launched?
Mariner 10 launched in 1973 and became the first spacecraft to visit Mercury.
When did the first spacecraft orbit Mercury?
MESSENGER entered Mercury orbit in 2011, becoming the first spacecraft to do so.
Whose mission first orbited Mercury?
NASA’s MESSENGER mission, with Sean Solomon as principal investigator, became the first spacecraft to orbit Mercury in 2011. It mapped the planet in detail until 2015.
Whose observations first revealed that Mercury has phases like the Moon?
Galileo Galilei observed the phases of Venus, not Mercury, but Giovanni Zupi first clearly reported Mercury’s phases in 1639. These phases supported the idea that Mercury orbits the Sun.
How does Mercury end up with such extreme temperature swings between day and night?
Mercury has almost no atmosphere to hold heat, so its sunlit side gets very hot while the night side cools rapidly. Daytime surface temperatures can reach about 430°C, while nights can drop to around -180°C.
Why does Mercury have such extreme day-night temperature swings?
Mercury has almost no atmosphere to store and redistribute heat, so its sunlit side can soar to about 430°C while the night side can drop to around -180°C.
Whose spacecraft first discovered that Mercury has a global magnetic field?
That was NASA's Mariner 10 in 1974. It was the first spacecraft to fly by Mercury and detected that the planet has a magnetic field.
How did Mercury end up with such a huge iron core?
Mercury’s core takes up about 70% of its radius, far more than Earth’s, likely because early impacts stripped away much of its original rocky mantle.
How do scientists know there is ice on Mercury?
Radar observations and spacecraft measurements showed that permanently shadowed polar craters on Mercury contain bright deposits consistent with water ice.
Why is Mercury covered in so many large cliffs and scarps?
Mercury shrank as its interior cooled, causing its crust to wrinkle and break into huge thrust faults. Some of these scarps are hundreds of kilometres long and up to about 3 km high.
When was the first probe sent to Mercury?
Mariner 10 was the first spacecraft sent to Mercury, launching on 3 November 1973.
Where is Mercury’s largest impact basin located?
Mercury’s largest impact basin, Caloris Planitia, is on the planet’s eastern hemisphere. It is about 1,550 km across.
Where is the largest known impact basin in the Solar System?
One of the largest known impact basins in the Solar System is Caloris on Mercury. It is about 1,550 km across.
Whose calculations first explained the tipping point that keeps Mercury in a 3:2 spin-orbit resonance?
Gérard de Vaucouleurs and later planetary dynamicists explained Mercury’s unusual rotation, which was confirmed by radar in the 1960s. Mercury spins three times for every two orbits around the Sun.