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Transit of Mercury: Watch Livestream as Planet Crosses in Front of Sun

Mercury is transiting across the disk of the sun in a rare celestial occurrence being broadcast online.
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It’s not nearly as rare as a transit of Venus, and perhaps not as captivating to the popular imagination as Mercury in retrograde, but the closest planet to our sun is at this very moment crossing between it and us.

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The event is being broadcast online, as highlighted by the National Museum of the American Indian. At 7:15 a.m. Eastern Daylight Time, Mercury began what Earthsky.org calls a “leisurely journey across the sun’s face,” with the midpoint occurring just before 11 a.m. and leaving the sun’s disk at 2:42 p.m.

Photo: Ryan Hagerty/U.S. Fish and Wildlife Service

The newly designated National Mammal roams on its traditional territory in the National Bison Range in Montana. President Barack Obama signed the National Bison Legacy Act into law on Monday May 9.

“The entire 7.5-hour path across the sun will be visible across the U.S. East—with magnification and proper solar filters—while those in the U.S. West can observe the transit in progress after sunrise,” Earthsky.org says.

The National Museum of the American Indian (NMAI) is among several organizations hooking up to observatories to broadcast the event as it happens. Another is the Slooh online community telescope, which takes footage from various observatories. Space.com is also hosting an online viewing party. One can also observe from the ground, with binoculars or a telescope—but make sure to use proper filters to avoid damaging vision. The same rules hold for a transit as for a solar eclipse. 

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This is what the path across the sun looks like.

Such transits help orient us humans to our place in the cosmos, and observations of cosmic phenomena date back for millennia. Since the advent of the telescope, the

“Mercury transits have been key to helping astronomers throughout history,” said NASA in a statement. “In 1631, astronomers first observed a Mercury transit. Those observations allowed astronomers to measure the apparent size of Mercury’s disk, as well as help them estimate the distance from Earth to the sun.”

If nothing else, watching the nearly infinitesimal black dot of Mercury pass across the relatively gargantuan orb that is the sun will serve as a humbling reminder of just how tiny we are, and what we have to be grateful for. Plus if you miss it today, you’ll have to wait until 2019 to catch it again.