On Monday, Mercury will pass between the Earth and the sun, a event that only takes place about 13 times every 100 years.
Scientists are planning to watch the transit of Mercury using Earth-based and in-space telescopes. The observations they gather could help researchers learn more about Mercury’s atmosphere.
The last transit of Mercury was in 2006, and the next one will be in 2019.
“Astronomers get excited when any two things come close to each other in the heavens,” Louis Mayo, program manager at NASA’s Goddard Space Flight Center, said in a statement. “This is a big deal for us.”
“Three of NASA's solar telescopes will watch the transit for just that reason.”
The transit — which lasts for about 7.5 hours — will be visible for millions of people around the world beginning at 7:12 a.m. and lasting until 2:42 p.m. ET, according to NASA.
The East Coast of the United States will be able to see the entire transit, while the West Coast will be able to see most of the event after the sun rises.
Do not try to look directly at the sun during the transit.
While Mercury will pass in front of the star from Earth’s vantage point, the small world doesn’t block that much light, meaning that it will still be very dangerous to look directly at the sun without proper protection using a telescope, binoculars or with the naked eye.
If you are interested in seeing the transit yourself, you’ll need some kind of magnification like a telescope or binoculars with a solar filter in place to see it.
You can also watch the transit live with NASA in near real-time thanks to the Solar Dynamics Observatory beaming back high-definition images of the sun from its post in space. NASA scientists will also participate in a Facebook Live event discussing observations of the transit from 10:30 to 11:30 a.m. ET on May 9.
Two other spacecraft will also watch the transit, according to NASA. The Solar and Heliospheric Observatory (SOHO) and Japan’s Hinode will also observe the sun during the transit.
“It used to be hard to observe transits,” Joseph Gurman, SOHO project scientist, said in the statement.
“If you were in a place that had bad weather, for example, you missed your chance and had to wait for the next one. These instruments help us make our observations, despite any earthly obstacles.”
Researchers use transits for science outside of the solar system as well. Some telescopes keep an eye on stars far from Earth to see when their light dips a slight amount, sometimes signaling that a planet has passed in front of its host star.