Tomorrow November 11 we’re in for a rare treat, as the innermost planet, Mercury, passes directly in front of the Sun for a few hours.

This event is called a transit, and for Mercury they happen only about 13 times in a century. (Transits of Venus are even more rare.)

Mercury transits the Sun. Credit: NASA/JPL-Caltech

The event will last about five and a half hours, during which Mercury’s path will take it right across the middle of the Sun’s disk.

For observers in the Eastern U.S., the transit begins after sunrise, meaning you’ll be able to view the entire thing.

For the central and western U.S., the transit begins before sunrise, but there’s enough time left as the Sun climbs up the sky for you to catch a glimpse before Mercury makes its exit.

You should never look directly at the Sun without proper protection, as it can permanently damage your eyes.

Mercury is so small in comparison that it can be next to impossible to see a transit without magnification.

Your best bet is a telescope with a certified sun filter, but other options include solar projection boxes and sun funnels. Plus, NASA’s Solar Dynamics Observatory spacecraft will be sharing near-realtime images during the transit. Whatever method you choose, be safe when observing the Sun!

The next Mercury transit that will be visible in the U.S. isn’t until 2049! So if you’re in the States, you might want to make the effort to catch this special celestial event.