DECEMBER SKYLIGHTS by Mark Dawson, Whitby & District Astronomical Society
December is chiefly all about solar system debris; both large and small and hopefully quite spectacular.
We are talking meteors (the Geminids) and comets – comet ISON to be precise. But let’s have a brief look at the visible planets first. Venus dominates the evening twilight sky over in the S-SSW quite close to the horizon and will be a dazzling spectacle over the Christmas period. A crescent moon lies above on the 5th. Venus is only visible for just over an hour after sunset. However, conspicuous Jupiter is well placed for observation almost from dusk until dawn. Look for it in the east during the evening – an unmistakable beacon. By midnight it lies to the south below the ‘twin stars’ of Gemini. Jupiter is a fine target for anyone with a telescope. The moon lies nearby on the 18th. Red Mars remains an early morning object, though is now starting to brighten, being relatively conspicuous over in the east by 3 am. The moon lies nearby on the 25th and 26th. The winter solstice is reached on 21 Dec: the Sun is at its lowest and daylight is at a minimum. But cheer up – in a week, nights will be putting out again!
December brings two meteor showers, the Geminids and the Ursids. The Geminids are actually the most prolific annual shower, peaking this year in the early morning hours of the 14th. Associated as debris from a strange object called Phaethon (may be a dead comet or an asteroid) Geminids are quite ‘rocky’ in nature and can produce brilliant fireballs. Rates may exceed 120 per hour, but moonlight will interfere this year so expect 25–40 per cent of this value. The Ursids peak around 22 December and it will be best to spot any before 9 pm of that night. Rates are between 8–12 per hour.
And so to Comet ISON, which may already be a news worthy item – or not. Comet ISON reached perihelion on 28 November when it slung shot around our Sun – just 750,000 miles above its surface at an astonishing 845,000 miles per hour. If the comet has not broken up it should be a spectacular sight during the first week of December – or at least the tail of it will be, either just after sunset over in the SW, quite close to Venus, and also just before sunrise over in the SE and near Saturn. If the comet is as bright as we hope it should be easily visible to the naked eye – even in relatively bright twilight. If ISON is not as bright as expected, binoculars should show the tail. This could be many degrees in length in the sky, equating to over 30 million miles. As the comet heads away it passes closest to Earth on 26 December, some 40 million miles distant. From 9 December ISON will be visible solely in the evening sky moving up past Hercules in the WNW and will be visible all night from mid-December. Who knows what ISON will do – your guess is as good as mine. Keep tabs on the media or visit www.whitby-astronomers.com.
Happy Solstice.
We are talking meteors (the Geminids) and comets – comet ISON to be precise. But let’s have a brief look at the visible planets first. Venus dominates the evening twilight sky over in the S-SSW quite close to the horizon and will be a dazzling spectacle over the Christmas period. A crescent moon lies above on the 5th. Venus is only visible for just over an hour after sunset. However, conspicuous Jupiter is well placed for observation almost from dusk until dawn. Look for it in the east during the evening – an unmistakable beacon. By midnight it lies to the south below the ‘twin stars’ of Gemini. Jupiter is a fine target for anyone with a telescope. The moon lies nearby on the 18th. Red Mars remains an early morning object, though is now starting to brighten, being relatively conspicuous over in the east by 3 am. The moon lies nearby on the 25th and 26th. The winter solstice is reached on 21 Dec: the Sun is at its lowest and daylight is at a minimum. But cheer up – in a week, nights will be putting out again!
December brings two meteor showers, the Geminids and the Ursids. The Geminids are actually the most prolific annual shower, peaking this year in the early morning hours of the 14th. Associated as debris from a strange object called Phaethon (may be a dead comet or an asteroid) Geminids are quite ‘rocky’ in nature and can produce brilliant fireballs. Rates may exceed 120 per hour, but moonlight will interfere this year so expect 25–40 per cent of this value. The Ursids peak around 22 December and it will be best to spot any before 9 pm of that night. Rates are between 8–12 per hour.
And so to Comet ISON, which may already be a news worthy item – or not. Comet ISON reached perihelion on 28 November when it slung shot around our Sun – just 750,000 miles above its surface at an astonishing 845,000 miles per hour. If the comet has not broken up it should be a spectacular sight during the first week of December – or at least the tail of it will be, either just after sunset over in the SW, quite close to Venus, and also just before sunrise over in the SE and near Saturn. If the comet is as bright as we hope it should be easily visible to the naked eye – even in relatively bright twilight. If ISON is not as bright as expected, binoculars should show the tail. This could be many degrees in length in the sky, equating to over 30 million miles. As the comet heads away it passes closest to Earth on 26 December, some 40 million miles distant. From 9 December ISON will be visible solely in the evening sky moving up past Hercules in the WNW and will be visible all night from mid-December. Who knows what ISON will do – your guess is as good as mine. Keep tabs on the media or visit www.whitby-astronomers.com.
Happy Solstice.