What’s that bright star near the Moon?

It’s a commonly asked question. As the Moon makes its regular orbital journey around the sky, it sometimes appears close to a particularly bright “star”.

Venus shines brightly above the crescent Moon in the evening sky. Image credit: Paul Sutherland

Often these stars are not stars at all but planets. Mercury, Venus, Mars, Jupiter and Saturn can all appear close to the Moon. That is because their orbits around the Sun are on a similar plane to the Moon’s around the Earth.

These planets also appear much brighter than most stars. Apart from the planets, a handful of first-magnitude stars – some of the brightest in the sky – also lie along the path travelled by the Moon, and so you might spot one close to it.

Occasionally, the Moon will actually pass in front of and hide a star or planet. Such an event is known as an occultation.

Here is a list of dates when the Moon may be seen close to a bright planet or star.


2021

April 2: Antares

April 6: Saturn

April 7: Jupiter

April 15: Aldebaran

April 17: Mars

April 20: Pollux

April 22-23: Regulus

April 26: Spica

April 29: Antares


May 3-4: Saturn

May 5: Jupiter

May 12: Venus

May 13: Mercury

May 15-16: Mars

May 16: Pollux

May 19: Regulus

May 24: Spica

May 27: Antares

May 31: Saturn


June 1: Jupiter


The Moon, shrouded in cloud, below Mars on 23 December, 2020. Image credit: Paul Sutherland

The bright stars that can lie close to the Moon all lie in constellations of the Zodiac. That’s because the Moon’s path through the heavens stays close to the ecliptic, the imaginary line around the celestial sphere marking the plane of the Earth’s own orbit around the Sun.

If you could switch off daylight, you would see that the Sun travels the full length of the ecliptic over the course of each year.

In order of brilliance, the brightest stars that can therefore be seen near the Moon are Aldebaran in Taurus, Antares in Scorpius, Spica in Virgo, Pollux in Gemini, and Regulus in Leo. They are all “first magnitude” stars.

But the brightest “stars” that you may spot near the Moon are not going to be stars at all, but rather the planets Venus, Mars, Jupiter and Saturn. One might add Mercury, the innermost planet in the Solar System, though it is never seen in a dark sky, and so is less likely to be noticed, especially as the Moon will be a very fine crescent when near to it.

Related: What to see in the night sky this month


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