Go stargazing on a dark night this month – away from street lights – and you’ll find that stars and the dazzling planet Jupiter aren’t the only sights to see.
The glowing band of the Milky Way arched overhead. And as your eyes become accustomed to the dark, you’ll also notice a handful of small, fuzzy spots in the sky.
These are star clusters, where hundreds or even thousands of stars live close together, held together by the bonds of their gravity.
Just above Jupiter lies the brightest and best-known star cluster, the Pleiades. My favorite description of this beautiful celestial sight comes not from an astronomer, but from the pen of Victorian poet laureate Alfred Tennyson. In his epic poem Locksley Hall, the Pleiades are “a swarm of ï¬reflies entangled in a silver braid”.
This star cluster is also known as the Seven Sisters, but naked-eye skywatchers usually see any number of stars, except seven! Like most people with moderate eyesight, I can make out the six brightest stars; but sharp-sighted observers can distinguish eleven or more.
These are the most luminous members of a group that includes at least a thousand stars, at a distance of 440 light-years. The brightest stars in the Pleiades are hot and blue, and all the stars are young: astronomers estimate that they are less than a hundred million years old, compared to almost 4,600 million years for the Sun.
Nearby in the sky, the Hyades star cluster is an older cousin of the Pleiades, dating back about 625 million years. More mature star clusters lack the enthusiasm of their younger cousins, because their original brilliant blue-white stars have died, leaving behind mainly their longer-lived yellow, orange and red siblings. The Hyades are therefore more massive than the Seven Sisters, even though the star cluster is three times closer – so close that the stars are clearly visible as individuals.
The stars of the Hyades date back to Babylonian times and formed the head of Taurus (the Bull). Aldebaran, which marks the evil eye of Taurus, looks like it’s part of the Hyades, but in reality this red giant star happens to be in the same direction, less than half the distance.
On the other side of the sky in Cancer you’ll find Praesepe, a more distant star cluster that appears as a faint point of light to the naked eye. The traditional Western name means ‘the manger’, with the blurry outline representing a loose bundle of hay. To ancient Chinese astronomers, this eerily glowing object was ‘the exhalation of piled corpses’!
In 1609, Galileo pointed the newly invented telescope at Praesepe and discovered that it was in fact a cluster of faint stars. A beautiful sight through binoculars or a small telescope, the swarming appearance of the stars has led to the nickname the Beehive Cluster.
Praesepe is about the same age as the Hyades and moves through space in approximately the same direction. Most likely, these two clusters were born together, from the same birth cloud of gas and dust, and gradually grew apart during their long wanderings around our Milky Way.
When they were young, Praesepe and the Hyades together may have resembled the beautiful Double Cluster in Perseus – on the border with Cassiopeia – which is only 14 million years old. These nearly twin star clusters, each covering an area the size of the Full Moon, are just visible to the naked eye and make a beautiful spectacle in binoculars or a small telescope. They are loaded with glorious young blue supergiant stars, with a dash of red giants to enhance their visual appeal.
Each of these clusters resembles Praesepe in our sky in brightness, but is severely dimmed by their distance – a whopping 7,500 light-years. If the Double Cluster were as close to us as the Hyades, their brightest stars would rival Sirius and we would see an area of the sky the size of Orion, crammed with a thousand celestial jewels.
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The two brightest planets bookend these long February nights. After sunset, Jupiter is a beacon in the west; you will find the Moon near the giant planet on February 14 and 15. And Venus rises in the southeast just before sunrise, with the crescent moon close by on the morning of February 7.
On the evening of February 16, the Moon will pass just below the center of the Pleiades, the Seven Sisters star cluster, hiding some of its fainter outlying stars.
On the star-studded stage, Orion rules the heavens, assisted by his two hunting dogs, Canis Major and Canis Minor. Its companions include Castor and Pollux, the twin stars of Gemini; Capella, at the head of the heavenly charioteer (Auriga); and Taurus the bull, with red giant Aldebaran.
These “winter stars” are best seen at this time of year; during the summer months they disappear below the horizon. In fact, all the stars in the southern part of the sky change with the seasons as the Earth revolves around the sun.
But we should not overlook the constellations in the north, the circumpolar stars that are visible all year round. Most famous are the seven stars of the team, which form the body of the Big Dipper, Ursa Major. Follow the two terminal stars of the Plow and they will lead you to the North Star, Polaris, which is always due north. In between, Draco, the dragon who guards the polar regions, squirms. And you can’t miss the W-shape of Cassiopeia, seen by the ancient Greeks as a queen sitting on her throne.
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February 2, 11:18 PM: Last quarter moon
February 7, early hours: Moon near Venus
February 9, 10:59 PM: New Moon
February 14th: Moon near Jupiter
15 February: Moon near Jupiter
February 16, 3:53 am: The First Quarter Moon occults the Pleiades
February 20: Moon near Castor and Pollux
February 23: Moon near Regulus
February 24: Full moon
February 28: Moon near Spica
Nigel Henbest’s latest book, ‘Stargazing 2024’ (Philip’s £6.99) is your monthly guide to everything happening in the night sky this year