Closest planet to the Sun. Smallest in the solar system. A world of extreme temperatures and a battered, ancient surface.
Mercury is the tiniest planet and the closest one to the Sun — and it absolutely zooms. It's a small, battered rock covered in craters, with no moons and barely any atmosphere. But don't let its small size fool you — Mercury hides some wild secrets!
Mercury is the closest planet to the Sun, yet it's not the hottest! Its days reach 430°C — hot enough to melt lead. But with no atmosphere to hold warmth, nights plunge to -180°C. That's a swing of 610 degrees!
Mercury races around the Sun at 47 km/s — faster than any other planet! One Mercury year is just 88 Earth days. But one Mercury day (one full spin) takes 59 Earth days. So one year is only one and a half days long!
Mercury's surface is covered in craters from asteroid impacts over billions of years. Scientists name them after famous artists, writers, and musicians. The biggest — the Caloris Basin — is 1,550 km wide. That's wider than Europe!
Mercury is actually really hard to reach! You'd think being close to the Sun makes it easy, but you have to slow down against the Sun's gravity — which takes huge amounts of fuel. Only Mariner 10 (1974) and MESSENGER (2011–2015) have made the journey.