That Tiny Dot? It’s the 2019 Transit of Mercury

By Anonymous

On Monday, Nov. 11, the planet Mercury will glide across the sun.

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.

How to watch the transit

Do not look directly at the sun.

NASA’s Solar Dynamics Observatory will post images and video in near real time, or search for a local astronomy club. The transit will be most visible in the Americas, especially along the East Coast, and Mercury will already be crossing when the sun rises 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.

That Tiny Dot? It’s the 2019 Transit of Mercury

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.

That Tiny Dot? It’s the 2019 Transit of Mercury

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.

That Tiny Dot? It’s the 2019 Transit of Mercury

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

That Tiny Dot? It’s the 2019 Transit of Mercury

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.)

That Tiny Dot? It’s the 2019 Transit of Mercury

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.”

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