Out & About Summer 2018

Star gazing

Newbury Astronomical Society’s NIC FLEET presents a round-up of some of the night sky highlights to look out for this summer – including a total lunar eclipse and the Perseid meteor shower

T he Summer Solstice, or midsummer day, is on June 21 this year and is when the sun reaches its highest point in the sky as we see it. Our sun is a huge ball composed mostly of hydrogen and helium gas. It’s so big that more than a million Earths would fit inside it. Its surface temperature is about 5,500 degrees centigrade, but it has a strong magnetic field that can disrupt areas as big as the Earth and reduce their temperature by around 1,000 degrees. They then appear as dark blotches that we call sunspots. You must never look directly at the sun, especially with a telescope or binoculars, as even a quick glimpse could permanently damage your eyes. However, astronomers can use special telescopes that cut out more than 99.9 per cent of the sun’s light and allow them to look at the sun safely. Check newburyastro.org.uk for any solar observing

Co-incidentally, Mars also reaches the point in its orbit directly opposite the sun from us on July 27. Mars will be at its closest and brightest around this time, so it’s a good opportunity to try and see its subtle surface markings and white polar cap with a telescope.

If you just have your eyes or a pair of binoculars, look out for a bright orangey star low down in the south east in the late evening. Mars is sometimes known as the ‘red’ planet because its soil contains iron oxide (rust) which makes its surface look ruddy. The highlight of the late summer stargazing calendar is definitely the Perseid meteor shower . The peak will be on August 12/13 and, as it’s a nearly new moon, conditions should be ideal. Meteors come from the small particles, around the size of a grain of sand, left behind by comets (and some asteroids) as they orbit the sun. When the Earth’s orbit crosses a trail of these particles they can collide with our atmosphere and burn up as shooting stars. The particles that cause the Perseids are travelling at around 60 km per second, which is why the meteors we see are typically very fast and bright. The comet that left the Perseid meteor

events we might be running this summer. On the evening of July 27 there will be a total eclipse of the moon visible from Newbury Although we don’t usually see it, the Earth casts a long shadow out into space opposite the sun. When the moon’s orbit takes it directly behind the Earth and it enters this shadow completely, we see a total lunar eclipse. The Earth’s shadow during a lunar eclipse is so big that the moon is immersed in it for over an hour. From Newbury, the moon will rise just after 8.50pm, already fully in the Earth’s shadow. Maximum eclipse will happen at 9.22pm and the moon will begin to leave the full shadow of the Earth at 10.13pm. An hour later the moon will clear the full

stream is a piece of dirty ice about 26km in diameter called 109P/Swift-Tuttle. It orbits the sun every 133 years and was last seen in 1992 – so it won’t be back again until 2126. The Perseid shower is named after the constellation of Perseus. You can tell if a meteor is a Perseid by following its direction backwards and, if it’s coming from the direction of Perseus, it’s a Perseid.

shadow of the Earth and after a further hour and 10 minutes completely out of the partial shadow. Even when the moon is fully in Earth’s shadow, some sunlight still gets to it because Earth’s atmosphere acts as a weak lens, bending the rays of the sun so that they can fall onto the moon. It will appear a bright coppery-red colour because as the sun’s rays travel through our atmosphere the blue light gets scattered more easily than the red light – so more of the red light gets through. That is why we often have orangey-red skies at sunset and sunrise. If it’s clear, towards the end of the eclipse have a look for the planet Mars, which will be about six degrees (roughly the width of three fingers held at arm’s length) below the moon.

The beauty of meteor-watching is that you just need your eyes. Meteors can appear anywhere in the sky so try and find an open area, away from street lights. A sun lounger, or deckchair, will let you relax and look up without craning your neck. It may be summer, but it can still get pretty cold out at night, so wrap up warm. In good conditions at the shower’s peak you can expect to see an average of one meteor per minute. Numbers tend to be higher after midnight so try and stay awake as long as possible. Keep a count of how many you see every half- hour – and tweet us, @newburyastro, to let us know how you’re getting on. Here’s to clear skies and happy stargazing.

To find out more about Newbury Astronomical Society visit newburyastro.org.uk

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