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The first planet from the Sun in the solar system. Mercury orbits the Sun at an average distance of 0.4 times Earth’s distance. The planet is just five percent as massive as Earth, and it about 50 percent larger than the Moon. It is made of solid, rocky material that is heavily cratered, and it has no significant atmosphere. Mercury has no moons.


Mercury March 7, 2016

Radio Programs

Moon and Mercury A bowling-ball planet January 24, 2017

Evening Mercury The incredible shrinking planet December 11, 2016

Moon and Mercury Some extra sunrises and sunsets September 27, 2016

Evening Mercury A hot spot on a hot planet April 15, 2016

Moon and Mercury A close but elusive planet April 8, 2016

Morning Mercury A dark planet in the dawn sky October 9, 2015

Evening Mercury Measuring a planetary day April 25, 2015

Venus and Mercury Pointing the way to a little planet January 9, 2015

Morning Mercury Getting closer to a little planet October 29, 2014

Venus and Mercury Bright, hot planets in the dawn sky July 10, 2014

Moon and Mercury Ghostly apparitions in the evening sky May 29, 2014

Evening Mercury Shrink-wrapping a small planet May 14, 2014

Mariner 10 at Mercury A first look at a little planet March 28, 2014

Mercury in the Morning An irritating planet in the dawn twilight March 13, 2014

Evening Mercury The wrinkled skin of a small planet January 30, 2014

Moon and Planets Two planets wander across the sky November 29, 2013

Dawn Planets Siblings with no family resemblance November 23, 2013

Venus and Mercury Artists land on another world June 16, 2013

Mercury Rising Cold pockets on a hot planet May 27, 2013

Mercury in the Evening A visit from a reticent planet February 15, 2013

Moon and Mercury Some interesting sunrises and sunsets August 13, 2012

Moon, Venus, Mercury Getting close to the Sun August 12, 2012

Moon and Mercury Peering into a small planet’s big heart June 20, 2012

Mercury in the Morning Teasing out a view of Mercury April 15, 2012

Evening Mercury Rethinking the birth of a planet March 4, 2012

Friendship 7 Getting back in the Space Race February 19, 2012

Featured Images

Mercury transits the Sun, May 2016

Little Black Dot May 10, 2016

2006 transit of Mercury

Spotty Sun May 6, 2016

Colorful Caloris April 15, 2016

View of Mercury from Messenger spacecraft

Dark Planet October 10, 2015

The Messenger spacecraft's final image of the surface of Mercury

The End April 30, 2015

Messenger view of the surface of Mercury

Getting Closer October 30, 2014

Venus, Mercury, and the earthshine-illuminated crescent Moon

Lighting the Shadows May 30, 2014

Mariner 10 at Mercury

First Encounter March 29, 2014

MESSENGER view of crater Degas on Mercury

Painting a Planet June 17, 2013

Messenger view of Mercury's southern hemisphere

Hard-to-Study Planet September 2, 2011

Messenger view of the surface of Mercury, June 2011

Hello, Sunshine July 2, 2011

MESSENGER's first color image of Mercury, March 29, 2011

First Glimpse March 31, 2011

Artist's concept of Messenger orbiting Mercury

Safe Arrival March 18, 2011

Planetary Tail April 6, 2010