Stargazing: Interesting Observations on the Moon
The Moon is the Earth’s nearest neighbour in space, and when you’re stargazing, it can be the brightest thing in the night sky. It’s also one of the most amazing sights seen through even a small telescope. If you look at only one thing through a telescope, it should be the Moon.
You need to observe the Moon in just the right conditions. At its brightest (during a full Moon), it can actually be a hindrance to astronomy, because it drowns out the light of the fainter stars; it’s like natural light pollution.
Stargazing: The Moon’s terminator
The best bit of the Moon to look at is the line between the lit part and the unlit part, which astronomers call the terminator line. If you were standing on the terminator line on the Moon, the Sun would be on the horizon, just rising or setting, and so the shadows are longest, just as on Earth at sunrise or sunset. Consequently, everything on the terminator – the mountains and the craters – stands out very dramatically.
And from night to night, as the Moon orbits the Earth, the terminator line moves across the Moon, showing different landscapes every night. Moongazers can therefore spend nights on end outside tracking down all the different features on the Moon’s surface. When the Moon is nearly full, though, it can be quite dazzlingly bright if you look at it through a telescope. You can buy lunar filters that block out some of the Moon’s light and make it more comfortable to observe when nearly full. A Moon atlas is a great purchase that can help you find your way around the Moon’s surface.
Turning a small telescope – or even a pair of binoculars – on a crescent Moon reveals a beautiful sight: mountain ranges standing next to fields of craters blasted on the Moon’s surface by rocks from space, and long shadows making everything stand out in 3D.
Stargazing: Moon craters
The craters on the Moon come in all different sizes, and the biggest ones are even visible to the naked eye. But through binoculars or a telescope, you can see hundreds – thousands! – of craters.
Craters all have a similar round shape. When viewed near the terminator of the Moon, the shadows cast by the Sun reveal the steep crater walls and perhaps a central bulge. You may also see rays stretch away from the crater across the Moon’s surface. These rays, called ejecta, are usually brighter than the surrounding Moon rocks.
Stargazing: A lunar eclipse
A lunar eclipse is the cousin to a solar eclipse and is much less dramatic, but it still makes a great sight for moongazers. As the full Moon passes into the Earth’s shadow, the Moon can appear to darken and then change colour, turning a dark red.
Lunar eclipses aren’t very common, but two things make them easier for you to observe than solar eclipses:
When a lunar eclipse happens, it’s visible from anywhere on the night side of the Earth.
Lunar eclipses are safe to observe with your eyes, binoculars and telescopes.
You can still see the Moon during the depths of a lunar eclipse, even though it’s entirely in the Earth’s shadow.
The Sun’s light gets bent (refracted) through the Earth’s atmosphere. The red light gets bent the most, and so that’s the light that illuminates the Moon’s surface during a lunar eclipse. What you see is the light from every sunrise and sunset on Earth lighting up the Moon’s surface!