‘Where do the Surrey Hills go at night?’ by John Evans

Where do the Surrey Hills go at night? Nowhere, of course. They’re still exactly where they were. But now as twilight softens the landscape and darkness falls, they undergo magical change, each transient moment suggesting new things of interest and beauty to explore. The creatures of the day make way for those of the half-light and the deep night. The colours of the day fade and the contours of the land slip away.

The Sun is reluctant to relinquish the day. Long after its disc snaps out below the horizon, the West clings to the glow of its scattered embers. With the coming of the New Moon, we see the Sun’s reflected light as a faint crescent, low in the evening sky. At this stage in the Moon’s cycle, you can often see the part of the Moon not lit directly by the Sun, glowing with a spooky light. How is this possible?

There is no atmosphere on the Moon to scatter sunlight. What we’re seeing is Earthshine – sunlight reflected from the Earth, now shining brightly in the lunar sky, beaming down onto the Moon’s night-time landscape. People used to call this “seeing the Old Moon in the New Moon’s arms”. Catch the New Moon around 16-17 November and you’ll see the Earthshine effect better in the few days following the Moon’s first emergence as a slim crescent.

As the Moon waxes, it is still the Sun’s light that we see lending the Moon brilliance to penetrate dark woods, shimmer on waters, bring silver to snowy hill-tops and, in the old days, give work-light at harvest time. On moonless nights, at least when there are planets in the sky, the chances are that sunlight will still be visible, for it is sunlight reflecting from the planets that enables us to see them. Through October, one planet is prominent in the evening sky: Mars, the Red Planet.

Naturally dark

And then there are the stars. The darker parts of the Surrey Hills are the best places in the county to experience something of the drama and inspiration of a naturally dark sky. There are plentiful viewing points and access is good; the Surrey Hills website is a superb source of guidance and information.

Such places are precious, not just for their daytime beauty but as oases of relative darkness. Decades of uninformed lighting design and practice consorting with carelessness and ignorance have given us light pollution on an unprecedented scale. Many people don’t realise that light pollution is a serious environmental threat. It wipes out the natural beauty of the night sky which, until recently, had always been there for humans to marvel at and draw upon for inspiration and understanding. It is associated with risks to human health and well-being. It damages wildlife and biodiversity. It is a visible sign of waste and contributes to climate change.

For all these reasons, it is for individuals and communities to reduce polluting light at night. Fortunately, it is quite easy to achieve this just by following good lighting practice and design and by switching off lights that are not needed. At the same time, the remaining places of relative darkness, such as those to be found within the Surrey Hills, deserve and need our support and protection.

“On a clear day you can see for miles.” But how far do think you can see on a clear night from the Surrey Hills? To the lights twinkling on the South Downs? Yes. Say, 30 miles or so. To the Moon. Yes. Roughly, a quarter of a million miles. To the stars. Yes. To that bright star there, Vega in the constellation of Lyra, the Lyre? About 25 light years, which is around 150 million million miles. Many of the others stars visible to the unaided eye are far more remote.

Beyond the Milky Way

Is that as far as you can see? Well, no. On a clear, moonless night from dark spots in the Surrey Hills, people with ordinary eyesight, with or without specs, can glimpse the Andromeda spiral galaxy, a vast star system, one of many billions in the known Universe, lying outside our own Milky Way galaxy. All of the stars you see in our sky are members, along with our own Sun, of our Milky Way galaxy. They are, relatively speaking, ‘locals’. When you see the Andromeda galaxy, you’re looking past and beyond all the stars in our own Milky Way to another vast spiral, separated from ours by enormous spaces, a galaxy broadly similar to ours but bigger and containing maybe twice as many stars. And, incidentally, due to collide with ours – but not for more than four billion years!

Finding the Andromeda galaxy is not difficult and this is a good time of year to do so. You’ll need a night with no bright Moon in the sky – the Moon has a fascination and beauty all its own but its brilliance makes faint objects in the sky impossible to see. First you’ll need to locate the Great Square of Pegasus. At 8 pm on 15 November, the Moon will not be obtrusive and, looking South from the Surrey Hills, the Square of Pegasus can be seen high in the sky.  Look for a big ‘square’ of moderately bright stars with no really bright stars within its boundaries. The chart will help you. Don’t worry if you miss this date – the starry sky changes slowly from night to night and Andromeda will be there to see for many weeks yet. On 15 November, below the Square and to the left, the planet Mars still shines bright and orange-red, though now moving away from its closest recent approach to the Earth. Throughout November and into December, it remains a good pointer to the Square – just look up from Mars and to the right and you’ll come to the Square’s bottom left hand corner.  Let your eyes continue a similar distance upwards and to the right and you come to its right hand top corner.  Phew! The Square looks big on the sky.

Now that you’ve got the Square, follow the line of stars that leads eastwards from its top left corner, about the same distance as the length of the Square’s side – you’ll stepping  stone  another star on the way. Climb the trail of faint stars that leads up at right angles from the track you’ve just followed, again for a similar distance. Can you glimpse a faint, misty glow? That is the Andromeda galaxy. From the Surrey Hills, it is there to see on moonless nights; from super dark places, it is easy to see.  It’s a good plan, but by no means necessary, to bring binoculars with you to help your search.

To have the best chance of seeing it, allow your eyes to become dark-adapted. That means not looking at lights for 20 minutes or so before you start. Dim red lights won’t affect your eyes too much but bright LEDs will. Be comfortable and warm. While heeding whatever is the prevalent distancing guidance, observe with others because it’s more rewarding, safer in the event of mishap and a lot more fun.

So how far can you see from the Surrey Hills at night?  At far as the Andromeda Galaxy, for sure. And how far is that? About 2.5 million light years or roughly 15,000,000,000,000,000,000 miles. So if anyone asks you how far you can see from the Surrey Hills, be sure to ask: “Do you mean by day or at night?”

Useful apps

Stellarium, free and useable across most devices, is a beautifully presented planetarium app that will help you find your way around the night sky for any place and any time of year.

Moon calendar: free, useful for tracking the phases and rising and setting times of the Moon so that you can plan your observing.

John Evans FRAS is Coordinator of the Dark Skies Matter initiative