Out & About Summer 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 summer months

degrees below the horizon, around 11pm and 3am. There’s still some debate about what causes the clouds to form. They were first recorded in 1885 and seem to have been becoming more frequent in recent years. It’s thought that water vapour freezes onto tiny dust particles which come from micro-meteors hitting the upper atmosphere, but the source of the water is still a mystery. Whatever their origin, keep an eye out for these beautiful and enigmatic clouds this summer. Perseid Meteor Shower

Mercury and Mars The planets Mercury and Mars will appear to be close together in the evening sky towards the middle of June, but this is an illusion. In fact, while Mercury’s orbit takes it between Earth and the sun in mid-July, Mars is almost on the opposite side of the sun from us – nearly five times farther away than Mercury. Mercury zips round the sun in just 88 days, so it pops its head above our horizon every few months either in the early evening sky or just before dawn. There will be two chances to catch a glimpse of this elusive planet this summer, right now (mid-June) and again at the beginning of August. If you have a pair of binoculars they will help you to get a better view of Mercury, but you should always wait until the sun has set fully before using them. Never look at the sun through any kind of optical aid – doing so could permanently damage your eyes. From June 10, Mars and Mercury started to approach each other low down in the north west after sunset. By June 16 they will be so close you could cover both with the end of your little finger held at arm’s length. Mercury will appear to be about as bright as the star Aldebaran in Taurus, but Mars will be more than four times dimmer. On June 18, at about 10pm, they will reach their closest point before moving apart and into the glare of the setting sun, by the end of the month. For early risers, Mercury will again be visible low down in the north east, from about 05.00, between August 9 and 15. Noctilucent Clouds

August is the time when the Earth’s orbit once again takes it through the stream of particles left by comet 109P Swift-Tuttle in its 133-year orbit around the sun. The comet last appeared in 1992 and is thought to be a lump of dirty ice about 26km across. When these sand-sized particles hit our atmosphere, they’re travelling at around 58km per second, so they burn up instantly causing the streak of light we call a meteor or shooting star. Because of the direction of Earth’s orbit, the meteors from comet Swift-Tuttle all appear to be coming from the constellation of Perseus, so we call the shower the Perseids. The Perseid meteor shower will reach its peak on August 13, although you may see some from late July to August 20. Unfortunately, the moon will be just past full on the night of the peak so bright moonlight might drown out some of the fainter meteors. However, if the sky is clear you can still expect to see a meteor every couple of minutes. Meteors can appear in any part of the sky, so just watch a clear area of sky as far from the moon as possible. Wrap up warm and lie on a mattress or a sun bed so you don’t get neck ache from looking up. There are several organisations in the UK who operate low-light CCTV cameras to record meteors. The UK Meteor Observation Network (UKMON) has a website where they post ‘live’ pictures of meteors from their cameras at - https://ukmeteornetwork.co.uk/ live/#/ They also post reports of fireballs, which are meteors that are brighter than the planet Venus. So, if you don’t fancy sitting outside, you can watch meteors from the comfort of your computer or mobile device. Happy observing!

Late June and July are the best months to look for ‘night-shining’, or noctilucent, clouds. These wispy high-altitude clouds form miles above our normal weather, about 85km up in a region of the atmosphere called the mesosphere. In the northern hemisphere they form in the summer months, when this layer of our atmosphere is actually at its coldest. They’re usually visible in the sky to the north, although strong displays can reach right overhead and they look like thin wispy clouds with a characteristic pale blue colour. Sometimes they have long streaks and a rippled texture reminiscent of the pattern that water makes on the bottom of a swimming pool. They’re best seen when the sun is about 10 to 12

newburyastro.org.uk

Pictures: Richard Fleet

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O&A SUMMER 2019