午夜福利1000集合

What you need

Binoculars

THE moon is our closest celestial neighbour. It is just 385,000 kilometres away, which means it is easy to see surface features using binoculars, and so get a glimpse into its history 鈥� and our own.

Unlike Earth, the moon has almost no atmosphere. This means there is nothing to slow down or burn up incoming rocks and dust, so everything hits the surface. You would never see a shooting star from the surface of the moon.

And because the moon isn鈥檛 geologically active, the signs of those impacts aren鈥檛 erased as they are on Earth. The moon is entirely covered in craters, some billions of years old, and studying them can tell us about the history of the solar system.

The best time to spot craters is two days either side of a full moon, when light from the sun highlights them clearly. The next full moon is on 13 or 14 October, depending where you live.

That鈥檚 true despite the moon being dimmer than normal right now. The moon鈥檚 orbit is elliptical, and on 10 October it reached its furthest point, or apogee, from Earth. At its closest point, or perigee, it is 50,000 kilometres nearer and appears 30 per cent brighter and 14 per cent larger than an average full moon.

The first thing to notice when looking at the moon are the dark and light areas. The dark parts are maria, basalt plains that formed from lava flows 鈥� and evidence that the moon was once volcanic. The lighter parts are the highlands, made of lighter-coloured rock.

In the middle of the big mare to the left is Copernicus, a crater 93 kilometres wide. You might see long streaks radiating out from it. These were formed by material thrown out by an impact 800 million years ago. We know the age because Apollo 12 astronauts took samples of this material; the landing site is just to the south.

You can also use Copernicus to find the Apollo 11 landing site. Look about a third of the moon鈥檚 width to its right and you can imagine Neil Armstrong stepping out of Apollo 11鈥檚 lunar module, Eagle, 50 years ago.

To the left of Copernicus is Aristarchus, the moon鈥檚 brightest crater. It is bright because the pale rock of its steep, 2.7-kilometre .

Now look at the south of the moon to find Tycho, a giant crater nearly 5 kilometres deep. In 1968, the uncrewed Surveyor 7 mission landed on its edge and analysis of its samples tell us the crater is just 108 million years old.

We always see the same side of the moon, thanks to the timing of its orbit. The so-called dark side of the moon looks quite different. Aside from the fact that it gets just as much sun as the side we see, so 鈥渄ark鈥� is a misnomer, maria cover just 2 per cent of the surface here, so it looks even lighter overall.

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For next week

You don鈥檛 need anything

Next in the series

1 Model the equinox

2 Find the North Star and Southern Cross

3 Test your area鈥檚 light pollution

4 Identify the craters of the moon

5 Orion and Sirius: how to star-hop A handy trick for stargazers

6 Planet spotting: Mars, Mercury and Uranus

7 Taurus and the zodiacal constellations

Stargazing at home online
Projects will be posted online each week at Email:maker@newscientist.com