Out & About Winter 2019

Out&About leisure

STAR GAZING

Newbury Astronomical Society’s NIC FLEET presents a round-up of some of the night sky highlights to look out for during the winter months

M ercury has been called the elusive planet because, although it can shine as brightly as our brightest star Sirius, it always appears in the evening or morning twilight and so tends to get drowned out by the sun’s glare. It’s the smallest planet in the solar system – discounting Pluto – only slightly larger than the Earth’s moon. It looks very like our moon too, barren, lifeless and covered in craters. Because it has a very thin atmosphere, the sunward side of Mercury can reach over 400˚C, while the temperature on the nightside can drop to -173˚C. However, despite the extremes of temperature, water ice has been detected in some permanently shadowed craters at the poles. Two spacecraft have visited Mercury to date. NASA’s Mariner 10 mission imaged about 45 per cent of the planet’s surface in the 1970s and then their Messenger mission orbited the planet between 2011 and 2015, imaging the rest of its surface and studying its composition and magnetic field. A third mission, named BepiColumbo, launched in October 2018 and is due to reach Mercury in December 2025. You too can catch this elusive planet in the evening skies at the beginning of February 2020. Look for Mercury low down in the west southwest, from about 5.30pm, between February 5 and 17. The planet Venus is back in the evening sky from mid-December, rising progressively higher in the southwest and getting brighter as the months progress. It passed around the other side of the sun from us last August and is now catching up with Earth in its orbit. By the end of January, it will be visible at 5pm, about 25 degrees above the horizon – and blazing away at operated by the European and Japanese Space Agencies, was

could see, the Quadrantid shower can equal the Perseids or Geminids – but Quadrantid meteors tend to be fainter, and the peak is much shorter. It’s thought this meteor shower originates from the particles left behind by an asteroid-like body, but it’s likely that the object is an extinct comet – possibly the one that was recorded by Chinese astronomers in 1490. If it’s clear, look out for the constellation of Ursa Major – the Great Bear – this winter. Also known as the Plough, or the Big Dipper, it will be low down on the Northern horizon at 9pm in early December. At this time, the Bear shape will be the right way up, but by early January it will look like it’s standing on its hind legs – and by mid-February it will appear to be balancing on its tail. This is because the constellation is rotating around the point in the sky directly above Earth’s North Pole. To find true north, just follow a line between the two pointer stars at the wider end of the ‘Dipper’ until you come to another star of about the same brightness. This is Polaris, the Pole Star, and if you point a camera at Polaris and take many photos over several hours, you’ll see that all the stars seem to revolve around it. This is, of course, due to Earth’s rotation, not the stars’ – however it does make a lovely picture.

magnitude -4. A slim three-day old crescent moon will make a pretty pairing with Venus on December 29. Look for them at sunset, low in the south southwest. If it’s cloudy, there’s another chance to catch Venus near the crescent moon on January 28 from about 5pm onwards – and again on February 27 from around 6pm. The planet Mars is now visible in the morning sky rising at about 5am GMT throughout Christmas apple the winter months. Look for it at about 7am, low down in the southeast. The gas giant planets, Jupiter and Saturn, will pass behind the sun in December and January respectively, so will be lost in the sun’s glare and difficult to see. The Geminid meteor shower peaks on the night of December 14/15. Unfortunately, the moon will be almost full on that night so its light will drown out the fainter meteors, however, it’s always worthwhile looking out for the brighter ones. Wrap up warm and watch any clear area of sky as far from the moon as possible to see most meteors. The Quadrantid meteor shower will peak at about 8am on January 4, 2020, so you can also watch out for meteors in the early hours. In terms of numbers of meteors you

Composite image of Quadrantid meteors

Picture: Richard Fleet

newburyastro.org.uk

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O&A WINTER 2019