Quadrantids bring New Year fireworks on the 4th
If one of our resolutions for the New Year is to get to grips with the sky at night, then we could hardly do better than start with our January evenings. The unmistakable constellation of Orion the Hunter rises in the east at nightfall and is the centrepiece of a star-strewn region in the south-south-east by our star map times. On the other hand, most of the brighter planets, and what may be our brightest comet of 2016, are best seen in the morning sky.
Just as last month brought the Geminids as the best meteor shower of 2015, so the imminent Quadrantids shower may provide our best display of 2016. Lasting from today until the 6th, but with most of its activity in the hours before dawn on the 4th, its medium speed meteors are seen in all parts of the sky but diverge from a radiant point below and left of the Plough’s handle. The Plough itself lies in the north at nightfall and climbs through the north-east and east to lie overhead before dawn.
Most of the constellation figures show little relation to the things, persons or animals they represent. Orion is a striking exception, for he has conspicuous stars at his shoulders and knees and an iconic line of three stars to define the belt around his waist. Admittedly, his head is marked only by a knot of fainter stars, although if we look carefully we can find an arc of other faint stars to represent the shield he holds in the face of the charging bull, Taurus. Another line hangs below his belt to form his sword.
Use binoculars or a telescope to inspect the sword and it is easy to spot the Orion Nebula, a cloud of gas and dust that lies some 1,350 light years away. This miasma of greens, reds and blues is a region where new stars are forming, together with their nascent planetary systems.
The line of Orion’s belt slants downwards to the brightest star Sirius in Canis Major, the larger of Orion’s two dogs. Extend the line the other way and we reach Taurus with its leading star Aldebaran in and the Pleiades star cluster. As Orion sinks towards our western horizon early on the morning of the 20th, Aldebaran is once again occulted by the Moon. As seen from Edinburgh, the star disappears behind the upper edge of the Moon just before 03:24.
It may be hard to believe, but the Earth is closest to the Sun for the year (147,100,176 km) when it reaches perihelion late tomorrow. Sunrise/sunset times for Edinburgh vary from 08:44/15:49 today to 08:10/16:42 on the 31st, while the Moon is at last quarter tomorrow, new on the 10th, at first quarter on the 16th and full on the 24th.
Jupiter rises at Edinburgh’s eastern horizon at 22:39 tonight and two hours earlier by the 31st. Now in south-eastern Leo and already twice as bright as Sirius, it brightens from magnitude -2.2 to -2.4 this month and reaches a so-called stationary point on the 8th when its easterly motion reverses to westerly. If you did get a telescope for Christmas, then enjoy the view of its fascinating cloud-banded disk which swells in diameter from 39 to 42 arcseconds. Jupiter stood near the Moon last night and the two are even closer on the 28th-29th.
Mars rises in the east-south-east by 02:15 and lies to the left of Spica in Virgo as they pass 25° high in the S before dawn tomorrow. The Moon is nearby on Sunday and even closer on 1 February, by which time Mars has travelled east-south-eastwards into Libra where it lies just above the double star Zubenelgenubi. Mars improves from magnitude 1.3 to 0.8 to overtake Spica in brightness, but is shows only a small 6 arcseconds disk through a telescope.
Venus continues as a brilliant morning star (magnitude -4.1 to -4.0) though its altitude in the south-east at sunrise sinks from 15° today to 8° by the 31st. It lies to the right of the waning Moon on the 7th when a telescope shows its disk to be 79% sunlit and 14 arcseconds wide. Venus is just 2° to the right of Saturn on that morning and within 7 arcminutes of Saturn on the 9th. At magnitude 0.5, Saturn is much the fainter of the two as it creeps eastwards in southern Ophiuchus.
Mercury has a few more days as a difficult evening star. It is bright at magnitude -0.2 tonight, but it hugs our south-western horizon at nightfall and sets less than 100 minutes after the Sun. As the month ends it is back in our morning twilight, a few degrees to the left of Venus.
Comet 2013 US10 Catalina has remained stubbornly below naked eye brightness in our morning sky, though photographs reveal a striking divergence between its tails of dust and ionized gas, the latter being torn and billowed by the solar wind.
Following perihelion 123 million km from the Sun in mid-November, the comet is closest to Earth (108 million km) on the 17th. Likely to appear as a small greenish fuzzy blob through binoculars, it moves from less than 0.5° west of the conspicuous star Arcturus in Bootes this morning to lie 1.2° east of Alkaid, the star at the end of the Plough’s handle, before dawn on the 15th. It is currently around the sixth magnitude but may be a magnitude dimmer by the month’s end as it sweeps within 9° of Polaris and recedes on a trajectory that will never bring it back towards the Sun.