Mercury Set to Cross the Sun in Rare Celestial Event

— -- Mercury is set to transit the sun, a celestial event so rare it happens just 13 times in a century.

The planet closest to the sun will begin its crossing at 7:12 a.m. ET Monday. Mercury will slowly journey across the face of the sun, appearing as a small black dot to people on Earth viewing the transit through a telescope or high-powered binoculars with solar filters, which NASA recommends on its website.

The entire journey will take Mercury 7.5 hours, with the planet exiting the sun's glow at 2:42 p.m. ET, according to NASA.

The space agency expects the event will be visible to skygazers in the eastern United States, while those in the West can enjoy checking in on Mercury's progress after sunrise.

Mercury's last trek across the sun was in 2006, according to NASA.