Two “full” solar-system bodies huddle close together tonight and tomorrow night: the Moon and the planet Saturn. Saturn looks like a bright golden star. It’s to the left of the Moon as darkness falls tonight, and closer to the upper right of the Moon tomorrow night.

Saturn and the Moon are full for the same reason — both are at opposition — they line up in the opposite direction from the Sun. At opposition, the Sun fully lights up the side of a body that’s facing our way, so the object is at its brightest.

Saturn reached opposition a couple of days ago. Now, it’s beginning to move out of that alignment. But it’s a slow process, so Saturn will stay at its peak brightness for a while.

The Moon will reach opposition tomorrow night. It’s the second opposition this month — the second full Moon — which makes it a Blue Moon; more about that tomorrow.

It’s also the closest full Moon of the year. Tomorrow morning — about 10 hours before the moment of full Moon — the Moon will be about 17,000 miles closer than average. It’ll still be quite close at the precise moment it’s full, tomorrow night.

You might think the Moon is always closest when it’s full, but that’s not so. There’s a difference of a couple of days in the periods of the Moon’s orbit around Earth and its cycle of phases. So sometimes the full Moon is farther than average. But that’s not the case tomorrow night — the night of a big, bright, blue Moon.
 

Script by Damond Benningfield

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