When you head out for stargazing on a dark night this month (well away from street lights), you’ll find that the sights on offer aren’t just stars and bright planet Jupiter.
The shining band of the Milky Way arcs overhead. And as your eyes adjust to the darkness, you’ll also notice a handful of tiny fuzzy specks scattered across the sky.
These are star clusters where hundreds or even thousands of stars live in close proximity, held together by gravitational bonds.
Just above Jupiter lies the brightest and best-known star cluster, the Pleiades. My favorite description of this magnificent skyscape comes not from an astronomer, but from the pen of Victorian poet Alfred Tennyson. In his epic poem Locksley Hall, the Pleiades are “a swarm of fire entwined in a silver braid.”
This star cluster is also known as the Seven Sisters, but naked-eye skywatchers often see any number of stars other than seven! Like most people with moderate vision, I can make out the six brightest stars; but sharp-sighted observers may select eleven or more.
They are the brightest members of a group of at least 1,000 stars located 440 light-years away. The brightest stars in the Pleiades are hot and blue, and all the stars are young: Astronomers estimate they are less than a hundred million years old, compared to the Sun’s nearly 4,600 million years old.
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 flavor of their younger cousins; The original bright blue-white stars have died away, often leaving behind their longer-lived yellow, orange and red siblings. but the cluster is three times closer; close enough that individual stars can be clearly seen.
Dating back to Babylonian times, the stars of the Hyades formed the head of Taurus (Taurus). Pointing to the Bull’s angry eye, Aldebaran appears to be part of the Hyades, but in reality this red giant star lies less than half the distance in the same direction.
Across the sky in Cancer you’ll find Praesepe, a more distant star cluster that appears as a faint speck of light to the naked eye. Its traditional western name means ‘manger’ and its blurred outline represents a loose bundle of hay. According to ancient Chinese astronomers, this eerily glowing object was the ‘Breathing of Stacked Corpses’!
In 1609, Galileo turned his newly invented telescope towards Praesepe and discovered that it was actually a cluster of faint stars. Its swarming appearance of stars, a spectacular sight through binoculars or a small telescope, has led to it being named the Beehive Cluster.
Praesepe is about the same age as the Hyades and is moving through space in roughly the same direction. Most likely, these two clusters were born together from the same birth cloud of gas and dust and gradually moved away from each other during their long journey around our Galaxy.
When young, Praesepe and the Hyades together may have resembled the beautiful Double Cluster in Perseus (bordering Cassiopeia), which is only 14 million years old. Barely visible to the naked eye, these near-twin star clusters, each covering an area the size of the Full Moon, are a magnificent sight when viewed with binoculars or a small telescope. They are full of glorious young blue supergiant stars and come with a sprinkling of red giants to add to their visual appeal.
Each of these clusters is similar in brightness to Praesepe in our sky, but is severely dimmed by their distance (a staggering 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 a region of the sky the size of Orion, filled with thousands of celestial gems.
What’s up
The two brightest planets separate these long February nights. After sunset, Jupiter is a beacon to the west; On February 14 and 15, you will find the Moon near the giant planet. Venus rises in the southeast just before dawn and a crescent Moon approaches on the morning of February 7.
On the evening of February 16, the Moon passes just below the center of the Pleiades star cluster, hiding some of the fainter stars in the distance.
In the starry scene, Orion rules the skies, aided and abetted by his two hunting dogs, Canis Major and Canis Minor. His friends include Gemini’s twin stars, Castor and Pollux; Capella advancing towards the celestial charioteer (Auriga); and the bull Taurus, featuring the red giant Aldebaran.
These “winter stars” are best seen at this time of year; In summer they disappear below the horizon. In fact, all the stars in the southern part of the sky change with the seasons as the Earth rotates around the Sun.
However, we should not overlook the constellations in the north, the circumpolar stars that can be seen all year round. The most familiar are the seven stars of the Plow, which form the body of the Great Bear the Great Bear. Follow the stars at either end of the plow, they will always lead you to Polaris, the North Star. Meanwhile, there is the return of Draco, the dragon who protects the polar regions. You can’t miss the W shape of Cassiopeia, who was seen by the ancient Greeks as a queen sitting on her throne.
Daily
February 2, 23.18: Last Quarter Month
February 7, early hours: Moon close to Venus
9 February 22.59: New month
14th February: Moon close to Jupiter
February 15: Moon close to Jupiter
16 February 03.53: First Quarter Moon obscures the Pleiades constellation
20 February: The Moon is 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) Your monthly guide to everything happening in the night sky this year