Mercury is the smallest planet in our solar neighborhood, the one which is closest to the Sun and, truth be told, Mercury is a serious badass survivor. Small, but with many mysteries.

As a collider of extremes — Mercury is a wrinkled, crater-covered celestial pal with a day on its surface lasting 176 Earth days, while the year on Mercury takes 88 Earth days.

This Monday, Mercury’s giving us a full-frontal show-off. It’s runway time!
It is a truly rare event — as a transit of Mercury across the face of Sun occurs for the last time this decade.

It actually happens only about 13 times a century and won’t happen again until 2032, so I know space geeks won’t miss today’s event.
What is a transit anyway?

A planetary transit happens when a planet crosses in front of a star. From Earth’s perspective, we only ever see two planets transit the Sun: Mercury and Venus.

Logically, as a third rock from the Sun, this is because these are the only planets between us and our star.

Transits of Venus, for instance, are especially rare. The last one was 7 years ago in June 2012, and the next one won’t happen until 2117.

During the upcoming transit of Mercury, viewers around Earth (using the proper safety equipment!) will be able to see a tiny dark spot moving slowly across the disk of the Sun.

Animated image of Mercury passing in front of the Sun during the 2016 transit of Mercury
NASA’s Solar Dynamics Observatory captured this view of Mercury transiting the Sun on May 9, 2016

Another question // Why are transits important to science?

Okay, we’ve learned that Mercury makes one orbit of the Sun in just 88 days, but as seen from Earth, the planet comes between us and the Sun in about every 116 days. 

Most times, Mercury passes above or below Sol’s disc are in May or November. Why Because, these are the months when the orbital planes of Earth and Mercury align, and the innermost planet can be seen passing directly in front of the Sun.

Given Mercury’s diameter of 4,879 kilometers, Mercury will appear as a small black dot silhouette just 1/196th of the Sun’s diameter.

The entire 5 ½ hour event will be visible, if the weather permits us the joy, in the eastern U.S. and Canada, and all of Central and South America.

The rest of North America, Europe, and Africa will catch part of the action. Asia and Australia will sadly, miss out on this transit.

So, basically, Mercury will be too small to see with the protected naked eye. To see it in transit, you must use a binocular or a telescope with a solar filter!

Bit, if you don’t have the appropriate equipment or the weather is cloudy, Slooh, a robotic telescope service, for instance, got us covered with an online live broadcast via Youtube, so we don’t have to wait until 13 November 2032 to see it again live.

Mercury will begin its journey across the Sun at 2:35 p.m. CEST, and the entire transit will take roughly 5 and a half hours, ending at 7:04 p.m. CEST.