Stargazing in January: Orion strides across the night sky

Striding across the sky this month is the giant figure of Orion, a familiar pattern of seven bright stars. According to ancient Greek tales, Orion was the most handsome man on Earth, with the power to walk over water. Armed with a mighty club and a massive sword, his greatest joy was hunting, and he boasted he would kill every creature on Earth.

Listening in to his words was the Earth-goddess Gaia. Appalled by this threaten of mass extinction, Gaia sent a scorpion to end Orion’s life by stinging his ankle. The gods honoured Orion by placing him among the stars. His nemesis was also elevated to the skies, but at a safe distance so that we see Orion during the winter, and the scorpion (the constellation Scorpius) in the summer time.

Orion’s Belt is marked by a line of three brilliant stars. Two stars above – including blood-red Betelgeuse – depict Orion’s shoulders, while a matching pair of stars below pick out the bottom of his tunic. Look carefully below the Belt, and you’ll spot a faint star representing Orion’s sword. Scrutinise it on really dark clear night, and you’ll see it’s actually a tiny faint glowing cloud.

Small and dim it may look in our skies, but that’s just due its immense distance: in reality, the Orion Nebula is vast seething maelstrom of incandescent gas, 24 light years in diameter. Through a telescope you can make out its swirls of gas, though our eyes are not sensitive enough to see any colours other than greyish green. The discerning eye of the Hubble Space Telescope reveals a cosmic butterfly, gaudy in the red light from hydrogen gas and the green tinge of oxygen atoms.

These gases are usually invisible, but here the atoms are being energised by the radiation from extraordinarily hot stars. Chief among these cosmic firebrands is a star known only by its catalogue number, Theta-1 C1. It’s 40 times heavier than the Sun, with a temperature of 40,000C, and shines 210,000 times more brightly than our star,.

Theta-1 C1 and its brightest neighbours are massive young stars, recently born from a dense cloud of gas and dust. The Orion Nebula is the tattered wreckage of their maternity ward, blasted apart by the energetic infant stars within.

These cosmic thugs have some 3,000 siblings, stars born at the same time, but smaller, fainter and less disruptive. The penetrating gaze of the Hubble telescope has revealed that many of the stars are girdled by dense discs of gas and dust, whirling around in the central star’s gravity. Each of these “proplyds” is the size of our solar system, and is a new system of planets in formation around its own sun.

And that’s just the beginning of the Orion Nebula’s secrets. Behind the young stars, planets and hot glowing gas there’s a vast dark cloud of cold, black dust and gas. It’s called the Orion Molecular Cloud, and it’s replete with exotic chemical compounds, molecules that would be the envy of any well-stocked chemistry lab. Pungent ammonia, bad-eggs hydrogen sulphide, and the mothballs stench of naphthalene all mingle together, along with poisonous molecules of cyanide and copious quantities of alcohol.

Under the force of gravity, the dark material in the Orion Molecular Cloud is curdling into hundreds of individual fragments. One day, they too will become new stars, firing up the Orion Nebula to even more splendour.

While in western mythology Orion the hunter represented death and destruction, to the Mayan civilisation the lower part of the constellation, centred on the Orion Nebula, was seen as the Hearth of Creation. Astrophysics shows that they had it right all along.

What’s up

The year opens with a planetary party, low in the southwest as the sky grows dark. Right on the horizon lies brilliant Venus. To its upper left, you’ll find fainter Mercury, then Saturn and at the end of the line giant Jupiter, second in brightness only to Venus. It’s all happening in the twilight glow, around 5pm, and binoculars will give you the best chance of spotting our neighbouring worlds.

All these planets have set by 8pm, and the night sky is dominated by the familiar outline of Orion, the great hunter (see main story). Follow the line of Orion’s Belt to the lower left and you’ll find Sirius, the brightest star in the sky. Also known as the Dog Star, it’s the jewel in the crown of Canis Major (the Great Dog). Above lies its slightly fainter litter-mate, Procyon, in the constellation of the Little Dog (Canis Minor).

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Higher still are the twin stars of Gemini, Castor and Pollux. And almost overhead, you’ll find Capella: the star’s name means “the little nanny goat”, though oddly enough it’s in the constellation of the Charioteer (Auriga). Sweeping down to the lower right, reddish Aldebaran marks the eye of Taurus, the Bull, with the lovely little star cluster of the Pleiades (the Seven Sisters) lying nearby.

By the end of January, the starry display remains much the same, but the planets have seriously shifted around. Only Jupiter is visible in the evening sky. Mercury and Saturn have disappeared into the Sun’s glare. And Venus has swung between the Earth and the Sun, and is now visible in the morning sky, accompanying Mars. The Red Planet lies to the right of the Morning Star, and is 250 times fainter.

Diary

6 January: Moon near Jupiter

7 January: Mercury at greatest elongation east

9 January, 6.11pm: First Quarter Moon

12 January: Moon near the Pleiades

13 January: Moon near Aldebaran

17 January, 11.48pm: Full Moon near Castor and Pollux

19 January: Moon near Regulus

20 January: Moon near Regulus

23 January: Moon near Spica

24 January: Moon near Spica

25 January, 1.41pm: Last Quarter Moon

‘Philip’s 2022 Stargazing’ (Philip’s £6.99) by Nigel Henbest reveals everything that’s going on in the sky this year