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 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.
Significant Events
- 1631: Thomas Harriott and Galileo Galilei observe Mercury with the newly invented telescope.
- 1631: Pierre Gassendi uses a telescope to watch from Earth as Mercury crosses the face of the Sun.
- 1965: Incorrectly believing for centuries that the same side of Mercury always faces the Sun, astronomers using radar find that the planet rotates three times for every two orbits.
- 1974-1975: Mariner 10 photographs roughly half of Mercury's surface during three flybys.
- 1991: Scientists using Earth-based radar find signs of ice locked in permanently shadowed areas of craters in Mercury's polar regions.
- 2008-2009: MESSENGER observes Mercury during three flybys.
- 2011: MESSENGER begins its orbital mission at Mercury, yielding a treasure trove of images, compositional data, and scientific discoveries.
- 2015: MESSENGER is deliberately crashed into Mercury after using all of its propellant, ending its mission.
- 2018: ESA's BepiColombo is launched.
- 2021: BepiColombo makes its first flyby of Mercury.
Notable Explorers
"Space missions are the result of teamwork requiring the efforts of numerous participants."
10 Careers That Explore Space
Astronaut
Astronauts pave the way for human exploration beyond our Earth. They are pilots, scientists, engineers, teachers, and more.
Project Manager
Project managers guide missions from concept to completion, working closely with team members to accomplish what they set out to do.
Rover Camera Operator
A camera payload uplink lead writes software commands that tell a rover what pictures to take.
The first thing that fired my imagination for planetary science was when the NASA Voyager spacecraft discovered active volcanoes on Jupiter's moon Io.
Artist
Melding science with design, artists create everything from large-scale installations to the NASA posters hanging in your bedroom.
Media Specialist
Media specialists tells stories across social media and help feature missions and people on TV and in films, books, magazines, and news sites.
Writer/Producer
Writers/producers capture the incredible stories of NASA's missions and people and share them with the world.
Administrator/Director
Administrators and directors work out of NASA headquarters, prioritizing science questions and seeking to expand the frontiers of discovery.
Educator
Whether it's introducing kids to space or teaching physics to PhD candidates, educators help share their knowledge with the public.
Engineer
Engineers design and build all types of machines, from what a spacecraft looks like to the software that directs where a rover goes each day.
Scientist
From an astrophysicist to a volcanologist, scientists of all types pose questions and help find answers to the mysteries of our universe.
The important thing about being a scientist or an engineer is learning how to think critically, learning how to be creative, learning problem solving and learning how to learn.
