Moon and Uranus

The Moon takes dead aim at one of the giants of the solar system tonight: Uranus, the seventh planet from the Sun. The planet will be close to the lower left of the Moon as they climb into good view, around midnight. The Moon will slide even closer to it as the night marches on.

As viewed from Hawaii and other parts of the central and northern Pacific, the Moon will actually cover the planet for a while — an event called an occultation. Uranus will disappear behind the bright limb of the Moon, then reappear on the dark edge.

Occultations require a precise alignment. Uranus lies close to the ecliptic, which is the Sun’s path across the sky. The Moon wanders back and forth across the ecliptic — sometimes to the north, some to the south. So most months, it’s too far from the ecliptic, so it gives Uranus a miss. Only when it’s at just the right location can it cover the planet.

That’s despite the fact that Uranus is big. It’s about four times the diameter of Earth — the third largest of the Sun’s major planets. But it’s also about 1.8 billion miles away, so it forms a tiny, faint disk in our sky — a big but tiny target for the Moon.

You need binoculars or a telescope to see Uranus. For most of the country, it’s a few degrees from the Moon as they rise, and a little closer at first light. It looks like a faint star with a hint of green.

Tomorrow: The Moon takes aim at a red planet.

Script by Damond Benningfield