Popular Astronomy

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What's Up for July 2017

It's an unfair world. All through the winter and spring the nights have been dark but it's been sooo cold. Now that the weather is getting warmer what happens? It hardly ever gets dark, particularly in Britain. You have to wait up till at least 10.30 in July to see any stars at all. And then you can hardly recognise any of them because they have changed totally since winter.

Use our easy-to-follow sky guide and you'll be out there stargazing in no time. You will need a star map, and you will need to know how it works. This may seem obvious, but there is a knack to understanding these things. Here's our map for this month:

Sky for July 17

Wrong way round?

Now don't write in and tell us that we have the points of the compass all wrong. This is a map of the sky, so you have to hold it over your head. When you do this, east and west will be the right way round.

It shows the whole sky, so the scale is quite small. Normally you turn to see different parts of it, so to see the view looking north, for example, hold the map upside down with north at the bottom.

The map shows the sky in mid July at about 10.30 pm, at the start of the month at 11.30 pm, or by the end of the month at 9.30 pm, though at this time of year the sky is too light to see anything at that time. All times are BST.

TIP If you aren't sure of the direction of north from your location, click here for a page on Getting Your Bearings.

Making sense of the stars

This being summer, the best way to find your way around the sky is to use the Summer Triangle. Actually this is not as obvious as it seems, because this triangle still remains visible well into the autumn and even the winter, but the fact is that it's a key feature of the summer skies so we might as well stick with the name.

Find it by looking right overhead to find a really bright white star, Vega. It's the only bright star close to being overhead, so ignore all other stars and look really high up. The next star of the triangle, Altair, is halfway between Vega and the horizon. Altair has a fainter star on either side of it – look at the map to get the idea. The other star is Deneb, which is a bit lower down towards the eastern horizon than Vega. If you can't spot these three stars straight away, remember that the map above is on quite a small scale, so think big and you should spot it.

Many people recognise The Plough, which if you want to get your bearings is quite high up in the northwest. We've picked it out on the map. If you think of the Plough as a saucepan, then follow its handle round towards the horizon, you come to a bright star called Arcturus, which is about the same brightness as Vega but lower in the western sky. It's also slightly yellowish, and if you thought all stars were white, compare it with Vega to see the difference.

Now use the map below to find more patterns nearby, but don't expect to see those convenient lines helping you to see the patterns. If you do see them, consult an optician or give back those glasses your friends gave you on 1 April.

Map for July 17 with constellation names
All maps produced using Stellarium software.

Other constellations to look for

This is the time of year to look way down on the southern horizon for the constellations of Scorpius and Sagittarius. Scorpius is the easiest to find because this year it has a bright planet nearby, namely Saturn. In fact, Saturn rather outshines the actual stars of Scorpius, such as Antares. From the UK we don't see the whole of Scorpius, just the top bit. You really must resist the temptation to call it Scorpio – only astrologers do that. 

To the left of Scorpius are the stars of Sagittarius, which form a sort of teapot shape, But unless you have a good, clear night and are well away from city lights, you might not see the stars at all well.

Above Scorpius are the stars of Ophiuchus, the serpent bearer. And above that is Hercules, whose most obvious feature is a parallelogram of stars called the Keystone, though it isn't particularly bright.

The map shows the Milky Way as a pale band crossing the sky. This is a good time of year to look for it, though you won't see it from light-polluted areas. The best chance of seeing it is high up in Cygnus, but if you go on holiday to a dark-sky area it can appear so bright you will wonder why you can't see it at home.

There are plenty of nebulae and clusters visible with binoculars in this part of the sky, so check out our guide to them.

If you want a map with all the constellation names on it, click here.

Your planets this month

The brightest planet around at the moment is Jupiter, fairly low over in the south-west. It's the brightest thing around apart from the Moon. Brightest in the evening sky, that is. And apart from planes. And the International Space Station, which will be around at the end of the month. Well, it's pretty bright anyway. 

Take a look at it through binoculars and you'll see some tiny starry objects on either side of it, which are its brightest moons. There are four of them, though you might not see all of them because they might be in front of or behind the planet itself. With a small telescope you can see the disc of the planet, and if you look carefully you should see two or more of its dark belts crossing the planet.

Jupiter is getting lower in the sky night by night, and next month will be much mnore difficult to see, so don't leave it too late to get your fill of the giant planet.

Saturn, photographed on 1 June using an 80 mm refractor by Robin Scagell

Saturn is to the left of Antares, and is quite a bit brighter. You don't need a super-colossal telescope to see its famous rings – any reasonably good small telescope should show them using a magnification of 50 or more. If it doesn't, it isn't (reasonably good, that is). However, with Saturn being so low in the sky as seen from the UK, our turbulent atmosphere will probably smear out any fine details no matter how good a telescope you've got.

Venus is around in the early morning sky, but with sunrise being so early you'll need to be up around 4 am to see it, over in the east.

Mercury is too close to the Sun to be seen from the UK.

For a detailed list of things happening in the sky, click here.

July shooting stars

Around this time of year the number of shooting stars – or meteors as astronomers prefer to call them – is on the increase. You may have heard of meteor showers, but these are more like meteor dribbles, really, with just fairly modest numbers – no more than a few per hour. They are known as the Alpha Capricornids and the Delta Aquarids, and they appear to come from the south-east part of the sky, but you could see meteors from these sources more or less anywhere in the sky towards the end of the month. Read more here. And there are are general background meteors, called sporadics, as well. Great for just gazing up on a warm summer evening and admiring the Milky Way, while shooting stars just zoom over your head. Well, that's the theory, anyway.

What about the Moon, then?

It begins the month at first quarter – that’s a half Moon – on the 1st, and then full Moon this month is on the 9th. Last quarter is on the 16th, then the month ends with New Moon on the 23rd. You might see the crescent Moon in the western twilight on the 25th about an hour after sunset, then there's another first quarter on the 30th.
This is the time of year when the full Moon appears very low in the sky. You will probably think it looks bigger than usual, particularly as it stays closer to the horizon for longer than it does in winter, but this is just an optical illusion. If you don't believe us, try measuring its size against a ruler held at arm's length, then measuring it again when it's higher in the sky.
So why does it appear bigger? It's nothing to do with the atmosphere acting as a lens – it doesn't. There are all sorts of theories, the most likely being that your brain compares it with objects such as houses or trees in the foreground and realises that because it is behind them, it must be bigger. Some people find that if they look at the Moon by turning away from it, bending over and looking at it through your legs, so you don't recognise the foreground as much, the illusion disappears. Unlike all those experiments where they say 'don't try this at home', you may want to wait until there is no-one else around before attempting this one. 
We have a whole section of this site about the Moon and what to observe, so do take a look.

Get more helpful info

OK, you've read all this for nothing, now comes the plug. This page is brought to you by the Society for Popular Astronomy, which is a really great society to join. It's based in the UK but there are members in other countries as well. It doesn't cost much to join, and there is a special rate for Young Stargazers. At least take a look at what we have to offer. 
Text by Robin Scagell