Mercury

Mercury

From the surface of Mercury, the Sun would appear more than three times as large as it does when viewed from Earth, and the sunlight would be as much as 11 times brighter.

10 Need-to-Know Things About Mercury

  • SMALL WORLD

    Mercury is the smallest planet in our solar system – only slightly larger than Earth's Moon.

  • INSIDE TRACK

    Mercury is the planet that orbits the closest to the Sun.

  • FASTEST PLANET

    Mercury is the fastest planet in our solar system – traveling through space at nearly 29 miles (47 kilometers) per second. The closer a planet is to the Sun, the faster it travels. Since Mercury is the fastest planet and has the shortest distance to travel around the Sun, it has the shortest year of all the planets in our solar system – 88 days.

  • ROUGH SURFACE

    Mercury is a rocky planet, also known as a terrestrial planet. Mercury has a solid, cratered surface, much like the Earth's moon.

  • CAN'T BREATHE THERE

    Mercury's thin atmosphere, or exosphere, is composed mostly of oxygen (O2), sodium (Na), hydrogen (H2), helium (He), and potassium (K).

  • MOONLESS

    Mercury has no moons.

  • RINGLESS

    There are no rings around Mercury.

  • TOUGH PLACE FOR LIFE

    It is unlikely that life as we know it could survive on Mercury due to solar radiation, and extreme temperatures.

  • BIG SUN

    Standing on Mercury's surface at its closest approach to the Sun, our star would appear more than three times larger than it does on Earth.

  • ROBOTIC VISITORS

    Two NASA missions have explored Mercury: Mariner 10 was the first to fly by Mercury, and MESSENGER was the first to orbit. ESA's BepiColombo is on its way to Mercury.

Exploration

Because Mercury is so close to the Sun, it is hard to directly observe from Earth except during dawn or twilight when the Sun's brightness doesn't outshine little Mercury. However, 13 times each century, observers on Earth can watch Mercury pass across the face of the Sun, an event called a transit. These rare transits fall within several days of May 8 and November 10. Previous transits occurred May 7, 2003, Nov. 8, 2006, and May 9, 2016, and Nov. 11, 2019.

The human on the moon The first spacecraft to visit Mercury was NASA's Mariner 10, which imaged about 45% of the surface. NASA's MESSENGER spacecraft flew by Mercury three times and orbited the planet for four years before crashing on its surface at the end of its mission.

The European Space Agency and JAXA launched a joint mission to Mercury in 2018. The mission, called BepiColombo, is made up of two spacecraft. ESA built the main spacecraft, the Mercury Planetary Orbiter, and JAXA supplied the Mercury Magnetospheric Orbiter.

BepiColombo captured its first views of Mercury during a flyby on Oct. 1, 2021. A total of nine flybys are planned to help steer the spacecraft into orbit in late 2025. It will begin its primary science mission in early 2026.

Twenty-four humans have traveled from the Earth to the Moon. Twelve walked on its surface. The last human visited the lunar surface in 1972.