This afternoon’s Mercury transit is a rare chance for people to witness our solar system’s smallest planet travel across the Sun.
Visible only as a tiny black speck floating across the surface of the Sun, the Mercury transit is an exciting moment for professional and amateur astronomers alike as it brings together the Sun, Earth, and Mercury all in near-perfect alignment.
The event became visible around 7 a.m. this morning on the east coast of the U.S., and will continue until about 2:45 this afternoon. The last time Mercury was in transit was in 2006, and though you’ll be able to catch it again in three years, if you miss out that time you won’t have another chance until 2032.
The first known Mercury transit was recorded in 1631, and it helped early astronomers determine the distance of Earth from the Sun (which is nearly 93 million miles).
The event also helps present-day scientists. Because astronomers can measure exactly where Mercury should be located in relation to the Sun, its movement will help calibrate the instruments NASA uses to observe the solar system.
If you don’t have NASA-caliber instruments or just can’t get out of work in time to find a telescope, don’t worry: Slooh Observatories is recording a live feed of the entire Mercury transit.