Out & About Autumn 2018

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 autumn months, in particular moon activity

T he planet Venus has been visible in the western evening sky for the past few months, gradually setting earlier and earlier as its orbit takes it between Earth and the sun. It will be lost in the sun’s glare from September to early November, but it will reappear in the morning sky in time for Christmas. The ancient Greeks knew Venus as the Evening Star, or Hesperos meaning ‘evening light’, when it appeared after sunset, and the Morning Star, or Eosphoros meaning ‘dawn bringer’, when it appeared before sunrise. The Greek word ‘hesper’, or in Latin ‘vesper’ (evening), is the origin of our word west – the direction of sunset. Whereas ‘eos’, meaning dawn, gives us the word east – the direction of sunrise. A crescent sight south west from about 7.30pm on September 13 , when the planet Jupiter will be a few degrees to the left. Or on September 14 when the moon will be a little higher. If you spot the crescent moon, look out for Earthshine on the part that’s not sunlit. This is sometimes called ‘the old moon in the new moon’s arms’ and is caused by sunlight reflecting off Earth and illuminating the moon’s surface in the same way that a full moon lights up the Earth. If you look at the unlit part of the moon you will see the same pattern of light and dark patches – craters and ancient lava lakes – that are visible when the area is in sunlight. Although the moon may look shiny and white, its colour is actually closer to that of tarmac and only reflects about 11 per cent of the sunlight that falls on it. Earth, however, has clouds and ice on its surface that help reflect around 37 per cent of the sunlight falling on it. It is also Earthshine While the full moon is more likely to get noticed, a thin crescent moon in the evening – or early morning – sky, is a beautiful sight. Look out for it low down in the

over three-and-a-half times the diameter of the moon, with around 13 times as much area to reflect the light. This would make Earthlight on the moon roughly 50 times brighter than moonlight on the Earth – perhaps not quite enough to read your Out & About magazine by, but not far off. Do you see what ISS see? Imagine you’re looking up at the night sky one clear evening. It’s a couple of hours after sunset and there’s a sprinkling of stars above you. You notice a light in the sky, low down in the west – it could be a plane, but it’s not making any noise and doesn’t have any flashing lights. It climbs higher into the sky, brightening all the time and is already much brighter than any of the stars – as bright as the planet Venus – with a slightly golden tint. You watch as it glides silently overhead and starts to descend towards the southeast. Then it fades, turning an orangey-red, until within a few seconds it’s gone. Congratulations – you have just had a close encounter with the International Space Station (ISS). The first module of the space station was launched 20 years ago, in November 1998. Its first resident crew arrived in November 2000 and it’s been inhabited ever since. It is now slightly larger than a football pitch and houses an

international crew of six. It orbits between 205 and 270 miles above the Earth and, at just over 17,000 miles per hour – which means it circles the globe every 90 minutes. Seeing the ISS is easy. Its orbit takes it over the southern UK several times a day, but it needs to be in sunlight and we need to be in relative darkness to see it. Fortunately, there are predictions of exactly when and where it will appear on websites like www.heavens-above.com/ or follow Newbury Astronomical Society on Twitter – @newburyastro – for updates.

The moon will be FULL on: September 25, October 24 November 23, and NEW on: September 9, October 9 November 7.

There will be opportunities to see the ISS in the evening sky between the end of September and the beginning of October – and in the morning sky at the beginning of November. Book your close encounter now.

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

Pictures: Steve Knight

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