The planet Mercury slid across the face of the sun on Monday.

Mercury ECLIPTIC Earth Mercury ECLIPTIC Earth Mercury ECLIPTIC Earth Mercury Earth

Mercury is the fastest planet, and if it orbited on the same plane as Earth we would see it pass in front of the sun every 166 days.

But Mercury’s orbit is tipped, so we only see it cross the sun in the rare November or May when Mercury rises or falls directly between the Earth and sun.



















Mercury appeared as a tiny black dot at 7:35 a.m. Eastern time. Its full transit across the sun took five and a half hours. Transits of Mercury happen about 13 times a century. Here are all transits since 1900. November transits are angled upward, as Mercury rises above the plane of Earth’s orbit. During these transits Mercury is close to the sun and moving quickly. May transits are less frequent and angled downward. Mercury moves slower and looks larger because the planet’s elliptical orbit has carried it farther from the sun and closer to Earth. This year Mercury passed closer to the center of the sun’s disk than any other transit this century. Here are two centuries of past and future transits, 1900‍–2100. The first documented transit of Mercury was on Nov. 7, 1631. And the next transit will be on Nov. 13, 2032.

How to watch the transit

Do not look directly at the sun. You need proper viewing equipment to view the transit safely.

NASA’s Solar Dynamics Observatory posted images and video in near real time, and local astronomy clubs hosted many events. The transit was most visible in the Americas, especially along the East Coast, and Mercury was already crossing when the sun rose on the West Coast.

The transit of 2016

The last transit of Mercury was on May 9, 2016. A NASA timelapse shows the tiny dot of Mercury sliding across the sun.

The transit of 1631

The first documented transit of Mercury was on Nov. 7, 1631. The transit was predicted by Johannes Kepler, who died in 1630, and observed by the French astronomer Pierre Gassendi.

An observation of the 1631 Mercury transit by Pierre Gassendi. Karl Galle/Linda Hall Library

A transit on Mars

In June 2014, NASA’s Curiosity rover looked up to observe a transit of Mercury from the surface of Mars.

It was the first transit seen from a planet other than Earth. Mercury appeared as a faint dot moving faster than two larger sunspots.

An observer on Mars might also see occasional transits of Earth across the sun, though the next one won’t be until November 2084.

Transits in The Times

The first transit of the 20th century made the front page of The Times on Nov. 15, 1907. An observer noted a “diffused ring” around Mercury that was thought to be evidence of an atmosphere. (The planet does have an extremely thin atmosphere, called an exosphere, of atoms blown into space by the solar wind.)

An article after the 1940 transit noted that transits were less important since astronomers had stopped looking for the theorized planet Vulcan between Mercury and the sun, but that transits “will be watched as long as there are observatories and astronomers.”







Subscribe to the Science Times newsletter and sync your calendar with the solar system.

Sources: NASA; Fred Espenak (NASA Eclipse and EclipseWise). Images by NASA, except where noted.



