StarDate

Moon and Sea Goat


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Capricornus may be the most inventive constellation of the zodiac. For one thing, all of its stars are faint, so it takes some work to see any kind of pattern there. And for another, it represents the oddest creature in the heavens: a sea-goat – the front half of a goat plus the tail of a fish.

It’s easy to find the sea-goat’s location early tomorrow, because the Moon passes quite close to its brightest star. Unfortunately, the Moon will overpower most of the nearby stars, so you might want binoculars to help you see them.

The sea-goat’s leading light is known as Delta Capricorni or Deneb Algedi – the tail of the goat. It’s about 39 light-years away. It’s actually two stars locked in orbit around each other. The main star is twice the size and mass of the Sun, and about eight times the Sun’s brightness. The other star is smaller and fainter than the Sun.

Twice a day, Delta Cap fades a bit. That’s because its stars orbit each other once per day. And they’re aligned in such a way that they eclipse one other during each orbit. The system dims a bit more when the faint star passes in front of the bright one, and a bit less when it’s the other way around.

The stars of Capricornus form a wide triangle. Delta Cap is at the left point of the triangle. It climbs into good view by about 1 a.m. less than a degree from the bright Moon.

Script by Damond Benningfield

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StarDateBy Billy Henry

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