A brilliant moon will dominate our evening skies in the week ahead. The month ends with a full moon. For the next week the gibbous moon moves through the zodiacal constellations Capricornus, where it is tonight. It moves onto Pisces, Aries and then finishes the month full in Taurus.

As the night sky shifts from summer to autumn and later winter, it is a good time to take note of the constellations overhead.

You may notice a collection of stars setting in the northwestern sky that form a near half circle. The six stars are distinct against an otherwise less interesting field of stars. This is the constellation Corona Borealis. You may have seen it overhead during summer, but its appearance is more pronounced now as it sits above the horizon just after twilight.

Corona Borealis is also called Northern Crown. It looks more like a crown than Ursa Major looks like a bear. In Greek mythology the constellation is tied to a wedding gift given by Dionysus to his wife Ariadne, the daughter of the King of Crete. In the tragic story, she later died and the precious gift was put in the sky for eternity.

There is a star in the middle of the corn barely visible to the naked eye star. Called R Coronae Borealis, the star has a reputation for unexpectedly dropping in brightness. Through a telescope, it looks like any star. But all of a sudden, the star shuts down and becomes considerably fainter, entirely unlike the sun, which is a constant.

Water temperature in Edgartown harbor: 62º F.