Inconstant stars in stunning New Year sky
Our evening sky is bursting with stellar interest but devoid of bright planets. Instead, Mars partners Jupiter in the predawn in the south-east to south while the impending spectacle of the annual Quadrantids meteor shower is rather blunted by bright moonlight.
The charts show Taurus high on the meridian, above and to the right of the unmistakable form of Orion whose brightest stars are the distinctly reddish supergiant Betelgeuse and the contrasting blue-white supergiant Rigel.
Between them lie the three stars of Orion’s Belt, while hanging below the middle of these is his fainter Sword with the Orion Nebula. The latter’s diffuse glow, visible to the unaided eye under decent conditions and obvious through binoculars, comes from a region where new stars and planets are forming. It lies some 1,350 light years away and is one of the most intensively studied objects in the entire sky.
Two iconic variable stars, Algol and Mira, are well placed in the evening. Algol in Perseus, the archetype of eclipsing variable stars, has two unequal stars that orbit around, and hide, each other every 2 days 20 hours and 49 minutes. Normally Algol shines at magnitude 2.1 and is almost identical in brightness to the star Almach in Andromeda, 12° to its west and labelled on the chart.
However, when Algol’s fainter star partially obscures its brighter companion, their combined light dips to magnitude 3.4, one third as bright, in an eclipse that lasts for about 10 hours and can be followed with nothing more than the naked eye. This month, Algol is at its mid-eclipse faintest at 02:45 on the 13th, 23:34 on the 15th and 20:23 on the 18th.
Mira, by contrast, is a single red giant star that pulsates in size and brightness every 332 days on average. It lies well to the west of Orion in Cetus, the sea monster of Greek mythology which was slain by Perseus when he rescued Andromeda.
During a typical pulsation, Mira varies between about magnitude 3.5, easy for the naked eye, and the ninth magnitude, probably needing a telescope. Unlike Algol, whose variability is like clockwork, Mira is less predictable and it has been known to touch the second magnitude, as it did in 2011. Now is the time to check, for it is close to its maximum as the year begins. Markedly orange in colour, it dims only half as quickly as it brightens so should remain as a naked-eye object throughout January.
Named for the extinct constellation of Quadrans Muralis, the Quadrantids meteors diverge from a radiant point in northern Bootes which lies low in the north at our map times and climbs to stand high in the east before dawn. Meteors are seen between the 1st and 6th but peak rates persist for only a few hours around the shower’s peak, due this time at about 21:00 on the 3rd when 80 or more meteors per hour might be counted by an observer with the radiant overhead in a clear moonless sky. However, with the radiant low in the north and moonlight flooding the sky at the time, expect to see only a fraction of these, perhaps trailing overhead from north to south.
Earlier on the 3rd, at 06:00, the Earth reaches perihelion, its closest point to the Sun in its annual orbit. Edinburgh’s sunrise/sunset times change from 08:44/15:49 on the 1st to 08:09/16:44 on the 31st. The Moon is full at 02:25 on the 2nd, only four hours after it reaches its closest point to the Earth for the entire year. There is a relatively modern obsession in dubbing such an event a supermoon, because the Moon appears 17% wider than it does when at its furthest. The difference between an average full moon and this one, though, is hardly “super” and far from obvious to the eye.
The Moon’s last quarter on the 8th is followed by new on the 17th, first quarter on the 24th and full again on the 31st when it passes through the southern half of the Earth’s shadow in a total lunar eclipse. Sadly, the event is over before sunset and moonrise for Britain.
Venus slips around the Sun’s far side to reach superior conjunction on the 9th and leave Jupiter as our brightest morning planet. Seen from Edinburgh, the latter rises in the east-south-east at 04:04 on the 1st and is climbing more than 15° high into the south before dawn. Conspicuous at magnitude -1.8 to -2.0, it creeps 4° eastwards to the east of the famous double star Zubenelgenubi in Libra and rises at 02:30 by the month’s end.
Mars, much fainter at magnitude 1.5, lies almost 3° above-right of Jupiter on the 1st and tracks more quickly eastwards to stand only 14 arcminutes (half a Moon’s breadth) below Jupiter before dawn on the 7th. The pair lie below the waning Moon in our predawn sky on the 11th when Jupiter’s cloud-banded disk 34 arcseconds wide and visible through any telescope, while Mars is still too small to appear interesting. Mars is brighter at magnitude 1.2 and stands 12° to the left of Jupiter by the 31st.
Mercury, bright at magnitude -0.3, may be glimpsed through binoculars as it hovers very low above our south-eastern horizon for more than 90 minutes before sunrise until the 8th. Given a clear horizon it may still be visible on the 15th when it stands 2.6° below-right of the vanishingly slender waning Moon. Saturn, half as bright at magnitude 0.5, lies 4° right of the Moon on that morning but is easier to spot by the month’s end when it rises almost two hours before the Sun.
This is a slightly revised version of Alan’s article published in The Scotsman on December 30th 2017, with thanks to the newspaper for permission to republish here.
Moon between Venus and Mars on the 2nd
The new year opens with the Moon as a slim crescent in our evening sky, its light insufficient to hinder observations of the Quadrantids meteor shower.
Lasting from the 1st to the 6th, the shower is due to reach its maximum at about 15:00 GMT on the 3rd. Perhaps because of the cold weather, or a lingering hangover from Hogmanay, this may be the least appreciated of the year’s top three showers. It can, though, yield more than 80 meteors per hour under the best conditions, with some blue and yellow and all of medium speed. It can also produce some spectacular events – I still recall a Quadrantids fireball many years ago that flared to magnitude -8, many times brighter than Venus.
Although Quadrantids appear in all parts of the sky, perspective means that their paths stream away from a radiant point in northern Bootes. Plotted on our north map, this glides from left to right low across our northern sky during the evening and trails the Plough as it climbs through the north-east later in the night. The shower’s peak is quite narrow so the optimum times for meteor-spotting are before dawn on the 3rd, when the radiant stands high in the east, and during the evening of that day when Quadrantids may follow long trails from north to south across our sky.
Mars and Venus continue as evening objects, improving in altitude in our south-south-western sky at nightfall and, in the case of Venus, becoming still more spectacular as it brightens from magnitude -4.3 to -4.6. Mars, more than one hundred times fainter, dims from magnitude 0.9 to 1.1 but is obvious above and to Venus’ left, their separation falling from 12° to 5° during the month as they track eastwards and northwards from Aquarius to Pisces.
On the evening of the 1st, Mars stands only 18 arcminutes, just over half a Moon’s breadth, above-left of the farthest planet Neptune though, since the latter shines at magnitude 7.9, we will need binoculars if not a telescope to glimpse it. At the time, Neptune, 4,556 million km away, is a mere 2.2 arcseconds wide if viewed telescopically and Mars appears 5.7 arcseconds across from a range of 246 million km. On that evening, the young Moon lies 8° below and right of Venus, while on the 2nd the Moon stands directly between Mars and Venus. The pair lie close to the Moon again on the 31st.
As its distance falls from 115 million to 81 million km this month, Venus swells from 22 to 31 arcseconds in diameter and its disk changes from 56% to 40% sunlit. In theory, dichotomy, the moment when it is 50% illuminated like the Moon at first quarter, occurs on the 14th. However, the way sunlight scatters in its dazzling clouds means that Venus usually appears to reach this state a few days early when it is an evening star – a phenomenon Sir Patrick Moore named the Schröter effect after the German astronomer who first reported it. Venus stands at its furthest to the east of the Sun, 47°, on the 12th.
The Sun climbs 6° northwards during January and stands closer to the Earth in early January than at any other time of the year. At the Earth’s perihelion at 14:00 GMT on the 4th the two are 147,100,998 km apart, almost 5 million km less than at aphelion on 3 July. Obviously, it is not the Sun’s distance that dictates our seasons, but rather the Earth’s axial tilt away from the Sun during winter and towards it in summer.
Sunrise/sunset times for Edinburgh change from 08:43/15:49 on the 1st to 08:09/16:44 on the 31st. The Moon is at first quarter on the 5th, full on the 12th, at last quarter on the 19th and new on the 28th.
The Moon lies below the Pleiades on the evening of the 8th and to the left of Aldebaran in Taurus on the next night. Below and left of Aldebaran is the magnificent constellation of Orion with the bright red supergiant star Betelgeuse at his shoulder. Soon in astronomical terms, but perhaps not for 100,000 years, Betelgeuse will disintegrate in a supernova explosion.
The relics of a supernova witnessed by Chinese observers in AD 1054 lies 15° further north and just 1.1° north-west of Zeta Tauri, the star at the tip of Taurus’ southern horn. The 8th magnitude oval smudge we call the Crab Nebula contains a pulsar, a 20km wide neutron star that spins 30 times each second.
The conspicuous planet in our morning sky is Jupiter which rises at Edinburgh’s eastern horizon at 01:27 on the 1st and at 23:37 on the 31st. Creeping eastwards 4° north of Spica in Virgo, it brightens from magnitude -1.9 to -2.1 and is unmistakable in the lower half of our southern sky before dawn. Catch it just below the Moon on the 19th when a telescope shows its cloud-banded disk to be 37 arcseconds broad at a distance of 786 million km. We need just decent binoculars to check out the changing positions of its four main moons.
Saturn, respectable at magnitude 0.5, stands low in our south-east before dawn, its altitude one hour before sunrise improving from 3° to 8° during the month. Look to its left and slightly down from the 6th onwards to glimpse Mercury. This reaches 24° west of the Sun on the 19th and brightens from magnitude 0.9 on the 6th to -0.2 on the 24th when the waning earthlit Moon stands 3° above Saturn.
This is a slightly-revised version of Alan’s article published in The Scotsman on December 31st 2016, with thanks to the newspaper for permission to republish here.
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.
This is a slightly-revised version of Alan’s article published in The Scotsman on January 2nd 2016, with thanks to the newspaper for permission to republish here. Journal Editor’s apologies for the lateness of the article appearing here.
Comet Lovejoy heralds an exciting year in astronomy
The coming year promises to be an exciting one in astronomy and space research. NASA’s New Horizons mission is due to make the first flyby visit to Pluto in July while Comet Churyumov–Gerasimenko is nearest the Sun a month later, hopefully with Europe’s Rosetta probe still alongside and in prime position to observe the comet in full flow. Whether we hear again from the Philae lander remains to be seen, but its controllers are hopeful that it may come back to life in the spring.
Closer to home, the highlight is surely the solar eclipse on the morning of 20 March. This is total for the Faroe Islands and Svalbard while from Scotland the Moon hides all but a thin sliver around the Sun’s lower limb. From Edinburgh 94% of the Sun is obscured but for observers in Kirkwall, Lerwick and Stornoway this jumps to 97%.
January should be interesting in its own right. Not only are all the planets on view, but the constellations centred on Orion dominate our evening hours and we have the prospect that Comet Lovejoy may be a naked-eye object as it climbs to the right of Orion.
The year begins with the Quadrantids meteor shower which is active from the 1st to the 6th but reaches a rather sharp peak at around midnight on the 3rd/4th when as many as 80 medium-speed meteors per hour might be seen under ideal conditions from a dark location. Sadly, the Moon is full on the 5th so all but the brighter meteors will be swamped in the moonlight this year. Quadrantids appear in all parts of the sky but their paths trace back to a radiant point that is plotted low in the north at our star map times. Later in the night the radiant follows the Plough as it climbs through our north-eastern sky.
You may find it surprisingly that the Earth is at perihelion, our closest to the Sun, at 06:36 on the 4th. The centre of our planet then lies 147,096,204 km from the Sun, 5 million km closer than it does at aphelion on 6 July. Sunrise/sunset for Edinburgh change from 08:44/15:49 on the 1st to 08:10/16:43 on the 31st as the duration of nautical twilight at each dawn and dusk shrinks from 96 to 85 minutes. That full moon on the 5th is followed by last quarter on the 13th, new moon on the 20th and first quarter on the 27th.
As the Moon climbs in the east on the evening of the 1st, it stands below the Pleiades and above-right of Aldebaran, the eye of Taurus. By 19:00 the whole of Orion is unmistakable in the east-south-east, moving into the south-south-east by our map times as the Pleiades glimmer on the meridian.
Our chart traces the path of Comet Lovejoy as it climbs from Lepus the Hare, at Orion’s feet, through Eridanus the River and Taurus as it approaches the star Almach in Andromeda as the month ends. Discovered in August by the Australian amateur astronomer Terry Lovejoy, the comet has brightened more than most people expected and reached the threshold of naked-eye visibility, the sixth magnitude, in mid-December.
During January I expect it to shine at around the 4th or 5th magnitude, fainter than the stars on our chart but perhaps similar in brightness to the Orion Nebula. As such, it should be visible easily through binoculars as a hazy smudge, probably smaller than the Moon and with brighter core around its nucleus. Indeed, it should be a naked-eye object in a dark sky once the current moonlight has subsided. Photographs show a greenish hue and a narrow striated tail more than 5° long pointing up and to the left, away from the Sun.
Comet Lovejoy takes about 13,500 years to orbit the Sun and reaches perihelion on 30 January at a distance of 193 million km. It comes closest to the Earth, 70 million km, on the 7th.
Jupiter remains our pre-eminent planet as it rises in the east-north-east some 90 minutes before our map times. Blazing at magnitude -2.5 to -2.6, it is now creeping westwards to the west (right) of the Sickle of Leo and crosses the meridian in the early hours. A telescope shows it to be 44 arcseconds wide when it stands above the Moon on the morning of the 8th.
Venus is a brilliant magnitude -3.9 evening star very low in the south-west as the night begins. It sets for Edinburgh at 17:07 on the 1st and at 18:58 by the 31st. Use it (and binoculars) to locate Mercury which shines at magnitude -0.8 as it moves from 3° below-right of Venus on the 1st to lie less than 0.7° to the right of Venus on the 11th. It then tracks to the right of Venus and lies 7° away by the 22nd when it is a difficult magnitude 0.9 object in the twilight. On that evening, the thin earthlit Moon lies 9° above Venus and 7° to the right of the orange-hued planet Mars (magnitude 1.2) which otherwise remains the brightest object low in the south-west at nightfall.
The other naked-eye planet, Saturn, rises in the south-east at about 05:20 on the 1st and almost two hours earlier by the month’s end, becoming the brightest object low in the south-south-east to south before dawn. This month it tracks eastwards from Libra to pass 1° north of the star Graffias in Scorpius. Look for Saturn 2.6° below-left of the waning Moon on the 16th when a telescope shows its globe to be 16 arcseconds wide within rings that span 36 arcseconds and have their north face tipped 25° towards the Earth.
This is a slightly-revised version of Alan’s article published in The Scotsman on December 30th 2014, with thanks to the newspaper for permission to republish here.
Jupiter and Orion rule our New Year nights
The annual Quadrantids meteor shower hits its intense peak even before Jupiter comes to opposition on the 5th. The giant planet shines brightly throughout our January nights and Orion, too, is ideally placed in a sky awash with bright stars.
What is missing, though, is any sign of Comet ISON. Any hopes that the comet might blossom into a spectacular sight during December were shattered when its icy nucleus failed to survive its brush with the Sun on 28 November. A so-called ghost of ISON did emerge from its perihelion, but this must have been a dispersing cloud of dust which soon disappeared. Searches since then, including by Hubble, have failed to spot anything at all. So much for the Comet Of The Century.
Our charts show the Pleiades in Taurus glimmering high in the south at our map times as Orion strides towards the meridian. Trailing Orion are his two dogs, Canis Major and Canis Minor, with their bright stars Sirius and Procyon. Together with Betelgeuse at Orion’s shoulder, these form the Winter Triangle. Orion’s immediate foe, of course, is Taurus the Bull whose main star Aldebaran lies against a more remote V-shaped star cluster, the Hyades. The tips of the bull’s long jutting horns are marked by the stars Elnath and Zeta Tauri and it is just 1.1° north-west of Zeta that we find the famous Crab Nebula. The debris from a supernova explosion recorded by Chinese astronomers in 1054, it lies about 6,500 light years away and appears as an oval eighth magnitude smudge through a telescope.
January sees the Sun climb 6° northwards as sunrise/sunset times for Edinburgh change from 08:43/15:49 on the 1st to 08:09/16:44 on the 31st. The Moon is new on the 1st, at first quarter on the 8th, full on the 16th, at last quarter on the 24th and new again on the 30th.
With no moonlight, and if the weather permits, this could be good year for Quadrantid meteors. The shower lasts from the 1st to the 6th but has an unusually brief peak when the meteor rate could reach 80 or so per hour for an observer under ideal conditions. That peak is expected at about 19:00 GMT on the 3rd when the radiant, the point in the sky from which the meteors diverge, lies rather low in the north so that only a fraction of the ideal number of meteors may be seen. Even so, I’d expect to see several long-trailed meteors speeding overhead from north to south. Later in the night, the radiant follows the Plough as it climbs through the eastern sky.
The brightest object on our charts, Jupiter, shines at magnitude -2.7, three times brighter than Sirius, when it stands opposite the Sun on the 5th. It then rises in the north-east at sunset, crosses our high meridian at midnight and sinks to set in the north-west at dawn. The arrow on our chart shows it tracking westwards against the stars of central Gemini, some 10° below and right of Castor and Pollux. As such, it is unmistakable above and to the left of Orion later in the night. Look for it to the left of the almost-full Moon on the evening of the 14th. Jupiter is 630 million km distant at opposition, its slightly rotation-flattened disk measuring 47 arcseconds in diameter.
Appearing even larger than Jupiter is the dazzling magnitude -4.3 evening star Venus which sinks from 10° above Edinburgh’s south-western horizon at sunset on the 1st to set itself 100 minutes later. A full arcminute in diameter but only 4% illuminated, its slender crescent is obvious through binoculars. Weather and horizon permitting, the view may be more stunning on the 2nd when Venus lies 2.7° below-right of the narrow arc of the 2% illuminated Moon.
Venus soon disappears from our evening sky as it sweeps through inferior conjunction on the Sun’s near side on the 11th. Within another four or five days, though, Venus reappears as a morning star in the south-east and by the 31st it rises two hours before the Sun, shines at magnitude -4.6 and is a 12% sunlit crescent 52 arcseconds across.
Mercury emerges as an evening star later in the month as it moves to lie 18° east of the Sun on the 31st. Between the 19th and 31st, its altitude in the south-west forty minutes after sunset doubles from 4° to 8° as it dims only slightly from magnitude -0.9 to -0.5. Use binoculars to spy it in the twilight if you have a favourable horizon.
Mars rises in the east in the middle of the night and is tracking eastwards against the stars of Virgo to pass 5° north of Spica on the 28th. Its pink-red glow brightens from magnitude 0.8 to 0.3 and its disk swells to 9 arcseconds by the month’s end, large enough for some surface detail to be visible telescopically. It is best to observe it when it is highest as it crosses the meridian at an latitude of almost 30° shortly before dawn. The Moon lies alongside Spica and below Mars on the 23rd.
Saturn, another morning object, is creeping eastwards in Libra, about 6° to the east (left) of the wide double star Zubenelgenubi. It rises in the east-south-east at about 04:20 on the 1st, two hours earlier by the 31st, and at mag 0.6 to 0.5 is the brightest object low down in the south before dawn. When it lies alongside the Moon on the 25th, its disk appears 16 arcseconds wide while its glorious rings are 37 arcseconds across and have their north face tipped 22° towards us.