How to safely watch Mercury's 5-hour transit across the sun
The solar system’s smallest planet will appear as a tiny black speck slinking across the sun Monday morning, in a rare celestial event.
The transit of Mercury, the innermost planet, began Monday morning around 7:35 a.m. EST. Weather permitting, the planet’s trip across the sun will be visible to most of the world for more than five hours.
“Though it takes Mercury only about 88 days to zip around the Sun, its orbit is tilted, so it’s relatively rare for the Sun, Mercury and Earth to line up perfectly,” writes NASA online.
The phenomenon only happens 13 or 14 times a century and it will be 30 years before North Americans see another one. While the next Mercury transit between Earth and the sun will happen 13 years from Wednesday (in 2032), it won’t be visible from North America until the next occurrence in 2049.
As always, it’s not safe to stare at the sun with the naked eye, though it won’t be visible anyway, without a telescope or binoculars fit with solar filters. NASA solar astrophysicist Alex Young told The Associated Press that it would take “exceptional vision” to spot Mercury’s transit. It’s the smallest planet at about one-third the size of Earth (a golf ball to our baseball). Young could barely see Venus, which is a larger, closer planet, in 2012 with solar-filter glasses when it made a trip across the sun.
“That’s really close to the limit of what you can see," he told AP. "So Mercury’s going to probably be too small.”
Earthlings can safely watch Mercury transit from the comfort of their own homes via various live-streams online, including a YouTube stream from the Griffith Observatory in Los Angeles, which begins at 9:15 a.m. EST.
It will take more than five hours for the planet to finish the trip, but Mercury will actually be moving at about 241,000 km/h.
Good morning, Sunshine! ☀️— NASA (@NASA) November 11, 2019
Today, Mercury will pass between the Earth & the Sun, silhouetting it against our home star. This passage will begin at approximately 7:35am ET and last for more than five hours. Here's how you can watch the #MercuryTransit: https://t.co/ZPf6Kf98Pa pic.twitter.com/xnE9QdNuMu