Odds are you don’t have any plans for 4:09 a.m. E.T. on Tuesday, Nov. 8. Assuming your calendar is indeed clear, it might be worth setting your alarm for that time, because it’s then that the last total lunar eclipse until 2025 will begin—and the show should be a dazzler.

A lunar eclipse occurs when the Earth passes directly between the sun and the moon, casting a deep shadow across the lunar surface. In theory, a lunar eclipse should happen monthly, since the moon and the sun are on opposite sides of the Earth once every 27 days during the lunar passage around the planet. But the moon’s orbit is inclined 5 degrees relative to the Earth’s equator, meaning that most of the time, the Earth’s shadow passes above or below the moon.

It is only about once every year and a half that the three bodies line up perfectly to make an eclipse happen. That year and a half frequency is just an average, however. Tomorrow’s total eclipse will actually be the second one of 2022—the last one having occurred on May 15. After this coming eclipse, a three-year wait for the next one will begin.

The eclipse begins when the Moon enters Earth’s penumbra, our planet’s lighter, outer shadow. That happens at 3:02:17 A.M. (all times are EST). The partial eclipse, which is when the Moon first touches Earth’s umbra (its darker, inner shadow), begins at 4:09:12 A.M. Totality starts at 5:16:39 A.M., with greatest eclipse at 5:59:09 A.M. Totality ends at 6:41:37 A.M.