So we’re heading for the end of the summer already and we here at the Planetarium can’t believe it – our favourite part of the year drawing to a close! While it can be quite hard to stargaze at this time of year, due to it being light so far into the night (when we would all rather be snuggled up in bed, I’m sure!) it at least isn’t as chilly as winter and can be a slightly more pleasant experience. And If you’re planning a camping trip this month, take the opportunity to do some impromptu stargazing, with this article as a guide!
The first thing that we will see (or rather, not see) in the August Night Sky this year is the new moon, taking place on the 4th of August. This is when the side of the moon facing us here on Earth, is facing away from the sun, so we see the dark side in full view. Saying that, there is no side of the moon that is always facing away from the light so maybe ‘dark side’ isn’t the best phrase to use (Yes I am critiquing Pink Floyd here). Just like Earth, the whole moon is illuminated over the course of an Earth month, as each face turns in and out of the sunlight. So, in the new moon phase, the moon is always between the Earth and the Sun. On very rare and special occasions a solar eclipse can occur during the new moon phase. The next Solar eclipse visible here will be a partial eclipse visible in 2025. We won’t see a total Solar eclipse until 2090.
The new moon is the best time of the month for stargazing, though, as the sky is blissfully dark, and so let’s take a look at some of the stars visible this month.
There are many constellations visible in the summer sky, too many to go through, but highlights include the summer triangle (Aquila, Lyra and Cygnus), Hercules and Ophiuchus.
I’m going to focus on the constellations we hear less about though, so the first is the constellation Draco. The great thing about Draco is that it is circumpolar from northern latitudes, so it is technically visible all year round from the UK and Ireland. The name, as you might imagine, comes from the Latin for ‘dragon’, and that is what Draco represents.
Draco contains a star with the name Thuban, which means head of the dragon. It can also be called by its designation Alpha Draconis. This star has an interesting history. At one point it was the pole star, lying directly above the North pole of the Earth. It happened, in fact, to be the pole star when the Egyptian Pyramids were being built, from 3942 BC to 1793 BC. The Pyramids themselves were actually built with one side facing North, so that each night the light of Thuban was visible from the entrance passage to the tomb. Thuban will even be the pole star again in the future, so we can look forward to seeing the effect again – but sadly not until 21,000 AD… Somehow I don’t think I’ll still be around then.
The brightest star in Draco is Gamma Draconis, also known as Eltanin, which is an orange giant star.
There are also a number of galaxy clusters in Draco, including Abell 2218. This is a huge cluster of 10,000 galaxies, roughly two billion light years away from Earth, which acts as a strong lens. Because of the gravity of these galaxies, light is bent around them creating a jumble of images, with some galaxies appearing multiple times in light ‘echoes’. This galaxy cluster was in fact even used as a lens to discover the most distant object in the universe (that we know of so far). The object is a galaxy 13 billion light years away, which can be seen as it was just after the big bang.
Draco also contains NGC 6543, a planetary nebula known more commonly as the Cat’s Eye Nebula. It lies about 3000 light years away, and was discovered by William Herschel. Planetary Nebulae are the remnants of small, dead stars, which have puffed off their outer layers and shrunk down to a white dwarf. A white dwarf is the dense core of the star, glowing slightly white right at the centre of the nebula. The outer layers of the star take on a certain ethereal vibe as when they puff off, they become a beautiful coloured ring around the small white remnant. Another famous example of a planetary nebula is the Ring Nebula, which is a favourite of amateur astronomers.
Another constellation rarely talked about is Lacerta. This faint constellation represents a small lizard, not surprising given Lacerta is Latin for lizard. The constellation itself looks a little bit like a ‘w’, just like the constellation Cassiopeia, and so it is sometimes referred to as ‘Little Cassiopeia’.
Within this constellation there are a number of interesting objects, open clusters like NGC 7243, another planetary nebula and some double stars, which could be binary star systems, where two stars orbit each other, or simply visual binaries, where the two stars happen to line up from our perspective. One of these optical double stars is Alpha Lacertae, which consists of one bright white star 103 light years away, with a dimmer companion star almost 340 light years away. They just happen to lie in a line of sight from Earth, while being nowhere near each other in space!
The Highlight of the month this August (if not the highlight of the year) will be the Perseids meteor shower which can be seen every August. This meteor shower is associated with the comet Swift-Tuttle, and appear to come from the constellation of Perseus. Watch out for this meteor shower throughout August, peaking on the 9 – 12 of August. Find somewhere dark to watch out for up to 100 meteors per hour.
The last thing to view this summer is the full moon, taking place on the 19th August this year. Not only is it the full moon, it is actually a blue moon – the third of four full moons this season.
So take your chances with the changeable weather and do some stargazing, especially if you are planning on a camping trip this year. It’s great fun and good for the mental health (something we all need occasionally)!
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