How to become a backyard astronomer
It’s never been a better time to turn your gaze heavenwards as the pollution clears from the skies making the view crystal clear.
Plus, they haven’t actually banned looking outside yet, or eyes, so this can all still be achieved, even in lockdown.
We asked Cambridge Astronomical Association chairman Paul Fellows for a lesson about the best sights to look out for in the night sky with the naked eye or, at a push, a pair of binoculars.
Paul says: “Now is a good time to try stargazing as the skies have become much clearer. Amateur astronomers from all over the country have been commenting on it. It just shows how the aircraft create so many contrails!
“ I’ve put together a tour of the night sky that you can do any clear evening which will help you find some of the major constellations and pick out some of the stars.”
Where to start
Just after the sun sets, the first thing you can see at the moment is Venus, which is very bright in the south west. It’s so bright you can see it even while the sky's still blue. As the sky darkens, Venus gets even brighter to the point where some people can’t believe that it is not UFO, because it is so much brighter than anything we are used to.
The reason why it is so bright is that Venus is just catching up with us. It orbits the sun more closely than we do and so it catches up and overtakes us on the inside and that means it is getting closer to the Earth day by day. If you look at it with powerful binoculars or a small telescope you can see that it looks like a roughly half phase moon rather than just a single point of light. We can see that detail because it is that near and quite large now. You won’t see any detail, but even with a modest bit of optical assistance you can see the half-moon D shape. You can’t see anything more than that because we are just looking at the atmosphere which is very, very thick and full of clouds and doesn’t allow a view of any details below on the surface at all.
The Moon can be looked at with the naked eye but with binoculars you can see the craters and the seas of the Moon, which are really just giant impact craters, but they look dark. The dark bits that you see on the Moon are very old and the light bits are very new and that’s because the solar wind from the sun gradually makes everything go darker and darker. The older it is, the darker it is. The light bits are where there has been a new impact of a space rock crashed into the moon and turfed up fresh material from underneath.
You can see how from night to night the phases change. As for supermoons, I wish that term had never been invented because there is only about 11 percent difference in size so you can’t tell.
The Goat Star
As it gets dark look straight up above your head and the first star to come out will be Capella. That will be directly overhead and is called the Goat Star.
Once it is fully dark just next to it there are three little tiny much fainter stars you will be able to see and those are called the kids, because they are the three little goats.
Sirius and Aldebaren
If you look to the south fairly low towards the southern horizon you will see the brightest star in the sky, Sirius. That is the Dog Star. And following on the animal theme, if you look to the left of where Venus is, you will find Aldebaren which translates as the red eye of Taurus the Bull and it is a red giant star, which gives it the red colour. Taurus has one very angry red eye staring down at us. You will see the colour very nicely with binoculars.
Orion and the Orion Nebula
If we keep going left from Aldebaren you get to the very striking constellation of Orion the Hunter, with four stars marking out the corners of Orion, they are supposed to be his shoulders and his knees i think. And then you have Orion’s belt which is three stars in a slightly sloping row across his middle and then hanging down from his belt is his sword. And if you look at the sword you will see there is a fuzzy patch in the middle of it and that is the great Orion Nebula. If you look at that with binoculars you will see this small horseshoe shaped area of glowing gas and that is where new stars are being formed. So that is a really good thing for children to search for. It’s very easy because it is signposted. You can go from Orion's belt, move down the stars of the sword and right in the middle of them is the Orion Nebula.
If you are lucky enough to have a telescope it will look even better because you can see into the fainter regions. It is a star nursery where stars are made.
The top left hand corner of Orion, of the four outer stars, is called Betelgeuse. That is a red giant as well which has been playing tricks on us recently. Is it going to explode any day now or some time in the next million years, we are not quite sure. They think it has been ejecting a whole load of dust which has been making it go dimmer. But these are part of the end stage for a star so it really could be about to blow up as a supernova. If it does then it will be visible in broad daylight for several months as a really bright star. It wouldn’t have an impact on Earth as it is far enough away not to be dangerous so we are alright - we have checked.
If you look at the opposite diagonal corner of Orion in the bottom right of the constellation you have a contrasting star Rigel, which is a blue giant star and it is a blue-white colour compared to the deep red of Betelgeuse, so it is good to look at one and then the other. A blue supergiant like Rigel won’t live very long. They only last about 10 million years. It is hugely more powerful than our sun and is putting out 100,000 times more energy than our sun does because it is burning so hot, which gives it the blue colour. The colour of stars is related to how hot they are. So Betelgeuse is a cool 3000 degrees and Rigel is a raging hot 20,000.
Now find Orion’s belt you can use it to point upwards to the right back to the red star Aldebaran in Taurus. But if you go down to the left you get to Sirius, the brightest star in the sky, You can use these as signposts in the sky. If you go up from Sirius you will find it’s near two procyon in the Little Dog star. Sirius and Procyon are the brightest stars and they are Orion’s hunting dogs as he is making his battle in the sky with Taurus the bull.
Going up from Procyon you find the twins of Gemini, Castor and Pollux, another pair of bright stars. They are on their own and pretty obvious.
Now turn around and look northwest where you will find the most popular constellation of all, the Plough or the Big Dipper, or The Saucepan. That will be at an angle in the north wesern sky and if you follow along the handle of the saucepan there are three stars making up the handle. You will notice the middle one is a double star, you can tell that even with the naked eye. They are called Mizar and Alcor and if you have binoculars you will see them even better, they really are a pair orbiting around each other. But it takes them about 400,000 years to do an orbit because they are quite a long way apart otherwise we probably wouldn't be able to see them as separate.
The North Star
Go to the bowl of the big dipper, the far end of it - use those as pointers to go and find the Pole Star or North star. Sweep left from the two stars at the far end of the saucepan, sweep across the sky and find your way due north to the Pole Star, about halfway between the ground and directly overhead. It is a lowly fairly modest star on its own and that's the Pole Star. It is called that because if you stood at the north pole and looked up it would be directly above your head and the sky seems to rotate around the Pole Star and it stays still. Of course it is us that are turning underneath the sky and the polestar is directly in line with the rotation axis. It stays still and the whole sky seems to spin around it every 24 hours. Around 5000 years ago it was pointing at a star called Vega instead, that was the Pole Star then which was about the time the pyramids were being built so the pyramids are all aligned with where the stars were 5,000 year ago, not as they are now. It has all moved over 5,000 years, which confused people for a long time.
If you have got binoculars you can go and find a few more things you can go back to Capella the star directly above your head and sweep the area below it with binoculars. You should be able to find three star clusters which contain several hundred stars each all packed together in a little knot.
Also the Seven Sisters star cluster, the Pleiades are close to Venus so you can sweep that area of the sky with your binoculars and you can even just see it with the naked eye, but with binoculars it is lovely.
There’s an app for that
There's a piece of software you can download for free on your computer or your phone called Stellarium which is absolutely brilliant at showing you a tour of the night sky with the constellations and you can zoom in on all the planets and their moons.
The one I use on my mobile phone outside is called Pocket Universe - you hold it up to the sky and it tells you what you are looking at.
If you want a view of three of the other planets you have to get up just before sunrise, which won’t be popular, but Mars, Jupiter and Saturn are lined up in a straight line just before dawn in the south east of the sky. That’s where they are hiding at the moment which is why we are not seeing them in the evening sky.
Make sure they are not too heavy, perhaps a nice pair of 8 x 40. Even modest binoculars will show the moon brilliantly, you might even just glimpse the rings of Saturn and you might be able to glimpse the moons of Jupiter as tiny specks with them, but they are hiding in the morning twilight at the moment.
Cambridge Young Astronomers
We run a Cambridge young astronomers group for seven to 11 year olds once a month on a saturday morning under normal circumstances. Obviously we are shut down at the moment and we have an 11 plus group on a monday evening once a moth and we do lots of observing through the year with the Cambridge astronomical association throughout the year.
We do all our events at the institute of astronomy at Madingley road in Cambridge. We have even got some loan telescopes that people can borrow if they are a member of the club when we are allowed to mingle again. Come october we do live observing every wednesday night during the autumn and spring terms
More by this authorAlex Spencer