Blog Archives

Scotland’s Sky in January, 2014

Jupiter and Orion rule our New Year nights


The maps show the sky at 21:00 GMT on the 1st, 20:00 on the 16th and 19:00 on the 31st. (Click on map to enlarge)

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.

Alan Pickup

This is a slightly-revised version of Alan’s article published in The Scotsman on January 1st 2014, with thanks to the newspaper for permission to republish here.

Scotland’s Sky in December, 2013

Comet ISON – probably not the Comet Of The Century


The maps show the sky at 21:00 GMT on the 1st, 20:00 on the 16th and 19:00 on the 31st. Arrows depict the motion of Jupiter and, later in the month, of Comet ISON. (Click on map to enlarge)

Comet ISON swept through its perihelion within 1,165,000 km of the Sun’s surface at about 18:38 GMT on 28 November, but did it even make it that far in one piece? There have been signs that its brightening was halting again and perhaps that its icy nucleus might be breaking up even before it encountered the extreme heat and tidal forces of perihelion. In my view, sensationalist claims that ISON would be the Comet Of The Century, visible in broad daylight and an unmistakable spectacle in our night sky, are about to be proved wrong. While I am duty-bound to speculate on its appearance as it emerges from the Sun’s glare, no-one knows exactly what if anything we will see.

After a disappointing few months, a sudden surge in ISON’s activity and brightness began on 13 November. I glimpsed it through binoculars three days later and it continued to brighten as it dived lower in our south-eastern pre-dawn sky, first passing the star Spica in Virgo and then Mercury, by which time it was near the fourth magnitude and disappearing into the twilight. Since then we have relied mainly on observations from spacecraft. Claims that it may have stopped brightening as the production of gas and dust from its nucleus fell dramatically, and even that the nucleus was already disintegrating, painted a pessimistic picture. However, the mood changed when ISON appeared to be remarkably healthy and intact in the final hours before perihelion.

Even if the nucleus does shatter, it may not spell the end of ISON as an interesting object. Its gas and dust has to go somewhere, and that may lead to the comet’s tail remaining visible, and possibly brightly so. Don’t miss any opportunity to look for it stretching almost vertically above our east-south-eastern horizon before dawn over the coming few days, perhaps beginning as early as 1 December. It may also be glimpsed reaching up and to the right from our western horizon after sunset.

The comet’s head and nucleus, assuming it survives, tracks almost due northwards in the sky, climbing steeply in the east before dawn and heading to a position halfway between the bright stars Vega and Arcturus on the 21st. Our “Looking North” chart picks up ISON at this point and depicts its progress onwards and upwards into Draco by the year’s end. It is closest to the Earth, 64 million km, on the 26th but will it still be visible at Christmas?

Even if ISON fails miserably, our December nights are a treat to behold. They begin with Venus blazing low down between the south and south-west as it sinks from about 10° high at sunset. The planet is at its brilliant best, magnitude -4.7, as it stands 7° below-left of the young Moon on the 5th and 12° below-right of the Moon on the 6th. By Hogmanay it sets 105 minutes after the Sun as seen from Edinburgh and is 59 arcseconds in diameter, near enough (42 million km) and large enough for its slender 4% illuminated crescent to be recognised easily through binoculars, and perhaps by the keenest naked eyes.

Our second prominent planet, Jupiter, rises at Edinburgh’s north-eastern horizon at 18:21 GMT on the 1st and only 16 minutes after sunset by the 31st. Conspicuous in the east at our map times, it passes high in the south six hours later and is sinking in the west before dawn. Jupiter lies some 9° below and right of Castor and Pollux in Gemini and is slowly retrograding (tracking westwards) to pass only 0.25° north of the third magnitude star Wasat or Delta Geminorum on the 10th. Telescopically, the Jovian globe swells from 45 to 47 arcseconds as the planet approaches opposition in early January.

Orion, stands to the south of east at our map times, and is impressive as it climbs to cross the meridian during the midnight hours. A line upwards along Orion’s Belt extends to Aldebaran and the Pleiades in Taurus. Look for the Moon close to Aldebaran on the night of the 15th and near Jupiter on the 18th.

Mars rises in the east at 01:00 on the 1st and 30 minutes earlier on the 31st. Tracking eastwards against the stars of Virgo, it improves from magnitude 1.2 to 0.8 this month as its disk swells from 5.6 to 6.8 arcseconds in diameter – still too small for surface detail to be seen easily through a telescope. Look for Mars above the Moon on Boxing Day morning. Our second morning planet, Saturn, lies in Libra and rises in the east-south-east at about 06:00 at present. By year’s end, though, it rises at 04:20 and shines at magnitude 0.6, making it the brightest object low in the south-east to south before dawn. Catch it above-right of the waning Moon on the 29th.

Only a few days before the end of its best apparition of 2013, Mercury shines brightly at magnitude -0.7 and stands almost 5° high in the south-east forty minutes before sunrise tomorrow.

The annual Geminids meteor shower is active from the 8th to the 17th and is expected to peak in the predawn hours on the 14th. The bright moonlight for most of the night may still allow several slow bright Geminids meteors to be seen as they stream away from a radiant point close to Castor, roughly where the M of GEMINI lies on our north star map.

The Sun reaches its most southerly point in our sky at 17:11 GMT on the 31st, marking the winter solstice. Sunrise/sunset times for Edinburgh vary from 08:19/15:44 on the 1st to 08:42/15:40 on the 21st and 08:44/15:48 on the 31st. Nautical twilight persists for about 95 minutes at dawn and dusk. The Moon is new on the 3rd, at first quarter on the 9th, full on the 17th and last quarter on the 25th.

Alan Pickup

This is a slightly-revised version of Alan’s article published in The Scotsman on November 29th 2013, with thanks to the newspaper for permission to republish here.

Scotland’s Sky in November, 2013

Comet ISON sweeps close to the Sun on the 28th

Star map for November, 2013

The maps show the sky at 21:00 GMT on the 1st, 20:00 on the 16th and 19:00 on the 30th. (Click on map to enlarge)

A brace of comets and the year’s best apparition by Mercury might be enough to tempt us outside during the chill predawn hours this month.

Let us start with the evening, though, where Venus remains poorly placed for our northern latitudes. Although it blazes brilliantly at magnitude -4.4, it stands less than 6° above Edinburgh’s south-south-western horizon at sunset on the 1st and sinks to set in the south-west only 91 minutes later. It is also at its greatest angle of 47° to the east of the Sun. On the 6th, it is 8° below and left of the young Moon and at a more southerly declination (celestial latitude) than at any time since 1930. Turning northwards again, it is 9° high in the south at sunset on the 30th, when it remains visible for 157 minutes and is brighter still at magnitude -4.6.

Our charts show the stars of the Summer Triangle, Vega, Altair and Deneb, tumbling into the west as the Square of Pegasus crosses the meridian. To the south of Pegasus are Pisces and Aquarius where the two most distant planets, Uranus and Neptune, shine dimly as binocular objects of magnitude 5.7 and 7.9 respectively.

The winter constellations are beginning to climb in the east, with their centrepiece, Orion, just rising below Taurus and the Pleiades. Jupiter, magnitude -2.4 and brighter than any star, rises 35 minutes before our map times and climbs to pass 56° high in the S before dawn. By the month’s end it has improved to magnitude -2.6 but has hardly shifted in position in Gemini, below and to the right of Castor and Pollux. The Moon is nearby on the night of the 21st/22nd when Jupiter’s cloud-banded disk appears 44 arcseconds wide if viewed telescopically.

Mars rises in the east at 01:17 on the 2nd and shines at magnitude 1.5 well up in the south-east, 10° below and left of Regulus in Leo, before dawn. Speeding eastwards into Virgo, it brightens to magnitude 1.3 by the 30th when it rises only 16 minutes later. Catch it below the Moon on the 27th.

Comet ISON is on track to graze within 1,100,000 km of the Sun’s surface when it reaches perihelion at 18:35 GMT on the 28th. However,  whether it will survive the encounter is anyone’s guess. Sadly, hopes that it would blossom into the Comet of the Century have been dimming by the day as its performance has fallen further and further below what most comet experts were predicting after its discovery more than a year ago. Even this summer, the expectations were that it would be an easy binocular object by now and that it would surpass Venus at perihelion. As it is, it has still not been sighted through binoculars and it is even being suggested that it may never be visible to the unaided eye.

Claims earlier in October that the comet was already on the brink of disintegrating were soon countered by Hubble telescope observations showing it still to be intact. Images show a greenish head or coma surrounding ISON’s nucleus, with a tail pointing away from the Sun and narrowing along its length. It is brightening, but only by as much as can be explained by the intensifying sunlight and there are few signs that it is actually growing larger and more active.

Plunging sunwards, Comet ISON crosses the Earth’s orbital distance today and may be a telescopic object near magnitude 8.5 some 8° below-left of Mars in the south-east before dawn on the 2nd. It may be as much as a magnitude brighter and Moon’s breadth right of the star Beta Virginis before dawn on the 7th and perhaps near the sixth magnitude, and visible through binoculars, when it lies 0.7° below-left of Virgo’s brightest star, Spica, on the 18th.

Mercury, meantime, is emerging from the Sun’s glare to become conspicuous low down in the morning twilight in the south-east. Between the 10th and 29th, it rises more than 100 minutes before the Sun, climbs to stand between 8° and 11° high 30 minutes before sunrise, and brightens from magnitude 0.6 to -0.7. It is joined before dawn by Saturn (magnitude 0.6) which stands just 0.5° above Mercury on the 26th.

We can use Mercury to locate ISON later in the period. The comet may yet become a naked-eye object with its tail slanting back towards Spica as it sinks from 7° to the right of Mercury on the 21st to lie 5° below-right of Mercury three days later. That may be our final view of it until after perihelion. Comet Encke, a much more predictable and reliable binocular fuzz-ball at about the fifth magnitude, sinks from 6° above-right of Mercury on the 13th to pass 1.5° right of Mercury on the 18th before we lose it in the twilight.

With Comet ISON no longer expected to excel at perihelion, and because of the serious danger to our eyesight, do not attempt to observe it close to the Sun. If its tail does unfurl spectacularly, though, it may climb steeply from our south-eastern horizon before dawn on the 29th and 30th.

As the Sun tracks southwards, sunrise/sunset times for Edinburgh change from 07:20/16:32 on the 1st to 08:18/15:45 on the 30th. New moon on the 3rd is followed by first quarter on the 10th, full on the 17th and last quarter on the 25th. The new moon brings a solar eclipse on the 3rd which begins as an annular or ring eclipse over the western Atlantic but soon evolves to a total eclipse whose narrow path tracks eastwards to cross equatorial Africa from Gabon to Somalia. Surrounding areas, but not Britain, see a partial eclipse.

Alan Pickup

This is a slightly-revised version of Alan’s article published in The Scotsman on November 1st 2013, with thanks to the newspaper for permission to republish here.

Scotland’s Sky in October, 2013

Mars meets Regulus as Jupiter dominates before dawn

Scotland's Sky in October, 2013

The maps apply at 23.00 BST on the 1st, 22.00 BST (21.00 GMT) on the 16th and at 20.00 GMT on the 31st. Summer time ends at 02.00 BST on the 27th when clocks are set back one hour to 01.00 GMT. (Click on map to enlarge)

Our main interests this month lie in our predawn sky where Jupiter shines brighter than any star and where Mars is in conjunction with the star Regulus in Leo. Sweeping close to Mars is Comet ISON which remains dim at present but may yet brighten to become an impressive sight later in the year.The Summer Triangle of Vega, Altair and Deneb still looms high on the meridian at dusk but has tumbled westwards by our star map times. Trailing behind it is Delphinus where a nova flared in August. That stellar outburst was still just visible through binoculars in late September but was perhaps on the verge of plunging much fainter as is becomes shrouded in dust forming in the wake of the explosion.

Our charts show the Square of Pegasus approaching the meridian as the Plough rotates counterclockwise below Polaris in the north and the “W” of Cassiopeia nears the zenith. Taurus and the Pleiades are climbing in the east while Gemini is rising in the north-east with the Twins, Castor and Pollux, one above the other.

Jupiter stands 8° below and to the right of Pollux and rises less than 30 minutes after our map times, climbing to prominence high in the south-south-east to south before dawn. The planet creeps 2° eastwards during October, passes only 7 arcminutes north of the magnitude 3.5 star Delta Geminorum on the 4th and is above the Moon on the 26th.  Jupiter improves from magnitude -2.2 to -2.4 this month and swells from 38 to 41 arcseconds wide if viewed telescopically.

Our other pre-dawn planet, Mars, stands above-left of the Moon on the 1st and again on the 30th. Rising for Edinburgh in the east-north-east at 02:27 BST on the 1st and by 01:18 GMT on the 31st, it is climbing well up into the south-east before dawn. From 9° above-right of Leo’s leading star Regulus as the month begins, it speeds eastwards to pass 1.0° north of Regulus late on the 14th and lie 9° below-left of the star at month’s end. It improves slightly from magnitude 1.6 to 1.5 but remains just fainter than the magnitude 1.4 of Regulus. Note, though, the contrast in appearance with Mars being steady and reddish while Regulus is bluish-white and twinkling. Through a telescope, the planet’s tiny ochre disk is 4 to 5 arcseconds wide.

Comet ISON remains something of an enigma. Discovered just over a year ago when it lay beyond the orbit of Jupiter, it has been diving towards the Sun on a path that carries it 1,100,000 km above the Sun’s surface on 28 November. Some predictions have it as bright as the full moon at that point, albeit swamped in the Sun’s glare. In fact, its brightening has been slower than most were expecting and it was still a dim 12th magnitude object in late September. Hopes remain that it will be a naked-eye object in mid-November and again during December when it may well sport an impressive tail.

Its orbit takes it within 10.5 million km of Mars on the 1st and it is already being observed by spacecraft at the planet. It stands 2.0° above-left of Mars in our morning sky on the 2nd, moving to lie within 0.9° of Mars on the 18th and 6° below-left of the planet by the 31st. We can only hope that it might be visible through binoculars by the month’s end.

An unfortunate fact concerning our autumn sky is that planets that lie to the east of the Sun are hugging our horizon at sunset. Take Venus, for example. As seen from Edinburgh at sunset on the 1st, the brilliant magnitude -4.2 evening star stands 135 million km away and 45° away from the Sun but is only 5° high in the south-west. It sets 53 minutes later and should be obvious as the twilight fades, but only if our horizon is clear. Contrast this with Australia where Venus is a stunning object 43° high in the W at sunset and remains visible for almost four hours.

The reason, of course, is that the planets never stray far from the ecliptic, the Sun’s apparent annual path against the stars. At present the ecliptic slants low across Scotland’s south-western sky at nightfall as it traces the Sun’s southerly motion until midwinter.

By the 31st, Venus stands 5° above Edinburgh’s south-south-western horizon at sunset, shines a little brighter at magnitude -4.4 and is 6° below-right of the Sun’s midwinter position against the stars. As Venus approaches to 101 million km this month, its telescopic diameter swells from 19 to 25 arcseconds while the dazzling sunlit part of its disk changes from 63% to 50%. Look for the planet 4° below the young crescent Moon on the 8th and 1.5° above the red supergiant Antares in Scorpius on the 16th.

We have no chance of seeing Saturn or Mercury which are both fainter and closer to the Sun in the evening sky than Venus.

This month the Sun tracks 11° southwards as sunrise/sunset times for Edinburgh change from 07:16/18:48 BST (06:16/17:48 GMT) on the 1st to 07:18/16:34 GMT on the 31st. Nautical twilight persists for about 82 minutes at dawn and dusk. The Moon is new on the 4th, at first quarter on the 12th, full on the 19th and at last quarter on the 27th.

The southern 76% of the Moon’s disk slips through the fringe of the Earth’s shadow on the night of the 18th/19th to cause a penumbral lunar eclipse. Although only a slight dimming may be noticed, at least the Moon is well placed being in Pisces in the middle of our southern sky. The eclipse lasts from 22:51 to 02:50 BST.

Alan Pickup

This is a slightly-revised version of Alan’s article published in The Scotsman on October 1st 2013, with thanks to the newspaper for permission to republish here.