Nights are starting to draw in again, so soon it’ll be stargazing season! September is when everything starts to become far more fun from an astronomy perspective. The short nights of July and August that required you to stay up until gone 11pm with a cross spouse complaining that you never come to bed early whilst you try to find some obscure deep sky object are gone. Happy times are here again!
So, what’s up for September?
There’s not much to see planet-wise this month if you don’t want to get up early in the morning; however, this isn’t a problem as Saturn is your best bet for evening viewing. This is a good thing, it can be seen in the Southwest in the evening and as darkness falls. Due to complex orbital mechanic reasons which we won’t go in to, now is a good time to view Saturn, as the rings are as open now as they ever are – their maximum tilt comes in October, when they’ll be at 27 degrees, making them easy to see. Seriously, it’ll be 15 years before they look this good again, so go look all this month. It’s low in the sky though, which makes seeing difficult unless you find a hill or a spot of coastline with a decent view to the South, but it’s still reasonably bright (0.4 mag) so it’s easy to spot. It’s between the constellations of Sagittarius and Scorpius. Nice and easy.
Things to go look for:
Try Lyra and Cygnus all of September. They’re really easy to find at this time of year, using the Lost Astronomer’s guaranteed, two-step, no – fail Cygnus/Lyra finding technique. It is:
Step 1: Go outside early on a cloudless night in September.
Step 2: Look straight up.
Congratulations, you’ve found Lyra and Cygnus.
Cygnus represents a swan, and Lyra a lyre or a harp or some other cosmic musical instrument. If you look at Vega (it’s the stupidly bright one basically directly above you, can’t miss it) and draw an imaginary line through Albireo you’ll come to another very bright star about the same sort of distance away, not helpfully on the little diagram above. This is Altair, and along with Deneb and Vega make up the asterism called “the Summer Triangle”.
There’s all sorts of interesting things in this triangle, some of which you can see with the naked eye, others which a good set of binoculars will bring out. Take a look at the blue chart at the top; even better, print it out and take it with you. Use a torch with a bit of red cellophane wrapped round it (red light doesn’t ruin your night vision). So, in the summer triangle, in order of difficulty you can see:
The Summer Triangle. Altair, Deneb and Vega. Naked eye visibility, can’t miss it. Vega has got a lovely blue hue to it; It’s a blue giant only 25 light years away, but it’s just over two times as massive as the Sun, so it’s got a much shorter lifespan (about ten times shorter) as it burns all its hydrogen fuel as quickly as possible. Blue Giants: Live fast and hot, die young and explody.
The Double Double: if you’ve got sharp eyes, you’ll be able to distinguish two stars right next to each other. They orbit each other, attracted by the other’s gravity. If you’ve got good binoculars, you’ll find that each of those stars is in fact a double itself! Two pairs of stars, dancing around each other, like a pair of couples waltzing. Gravity is awesome.
The Ring Nebula: You’ll need binoculars for this one. It’s the shell of a dead star, outer layers blown away as gravity is no longer strong enough to contain them against the outwards force of the core. Through binoculars or a small telescope it looks like a grey smoke ring, very clearly distinct from the stars around it. Try not to look directly at it, but rather around it, you’ll see in much better that way (trust me and try it). Invisible at the magnification available to a garden astronomer is the White Dwarf at its centre (see the professional picture below), which is about the same size as Earth. Surrounded by the perpetual beauty of its escaping hydrogen gas shells, it is the broken heart of the star, shattered and slowly cooling to the black cinders of extinction.
Also visible through binoculars is the globular cluster M56:
You remember how the double-double was dancing around each other? Now imagine that with about 200,000 to 250,000 of the buggers, and that’s a globular cluster. I’m not going to lie, finding this one is a challenge – it’s quite faint. That just makes it more rewarding.
Anyway, other events for this month:
Flyby of asteroid Florence. You’ll need a telescope to see it, and it’s not really beginners’ stuff, but it’s too cool not to include.
5 Sept: Neptune at opposition: the distant world is at its highest point in the sky, and this time of year is the time to observe it. Unless you have a decent sized telescope and know what you’re doing, don’t bother with this one. If you do, you don’t need me to tell you where it is. Should you go looking for it, it’ll look like a tiny blue dot, and it’ll be hard to spot because of the nearly full moon washing everything out. Finding it is its own reward. Mars is also pretty good if you want to get up early to see it; it’s only visible from dawn in the Eastern sky. It’s bright, with a red hue.
6 Sept: Full moon. It’s really obvious. Apparently Native Americans called this the Harvest Moon, but I have my doubts about that as I thought Native American tribes were strictly nomadic and didn’t much go into agrarian farming, but then I’m not an anthropologist, so I could be wrong. In the UK it goes by the colloquial name of Full Moon, or amongst amateur astronomers it’s called Gosh, it’s bright out, there’s no bloody point tonight, is there?
9 Sept: Piscid Meteor shower. Expect about 10 meteors an hour, radiating from the constellation of Pisces. Don’t look directly at Pisces, as they radiate away from it, but rather take a deckchair and sit out in the garden with a blanket from about 2130 GMT and something warm to drink. Don’t use binoculars or a telescope, you’ll miss them, just sit back and admire the sky. At only ten an hour you might not see any, but that doesn’t mean you shouldn’t try. If you see something slow moving, steady and about as bright as most stars, it’s a satellite. If it blinks with flashing lights, it’s an aircraft. If it zips into life and extinguishes in less than a second, streaking across a chunk of sky as it does so – that’s a meteor. Make sure you turn off the kitchen light; it’ll ruin your night vision.
12 Sept: Best time to observe Mercury, as it is at its most Western Elongation. Get up reasonably early (before dawn, obviously, say about 5am, 5.30 local time), look to the East, and it’ll be one of the last bright dots to fade away before sunrise, low in the Eastern sky. The Moon will also be pretty nice whilst you’re there, thinning to a crescent, along with Venus. Marvel at the majesty of the cosmos, then go back to bed.
13 Sept: Last quarter moon. Evening viewing is now possible with a minimum of disruption from the moon.
15 Sept: The Cassini mission ends today; the plucky little probe has been returning images of Saturn for the past 15 years or so, landing a smaller probe on Saturn’s moon Titan in the process. Hugely successful, with enough discoveries to fill an entirely separate blog post, the mission comes to an end today as it crashes into Saturn, burning up in a $3.26Bn blaze of nuclear glory to prevent contamination of Saturn’s moons, which may contain life. If you go outside and listen carefully, you’ll hear my anguished sobs.
16 Sept: If you get up before dawn, you’ll see three planets (Venus, Mars and Mercury) and the moon in a wonky line pointing towards the Eastern horizon.
20 Sept: New moon. Perfectly dark skies, so it’s the best time of month. For true amateurs, take a pair of binoculars outdoors, find a comfy chair, and relax. Look up at random things. Pick something. If you don’t have a pair of binoculars, take a garden chair, go outside, and just look at the stars. Familiarise yourself with the patterns they make, they’ll soon become old friends. Let your eyes adjust to the darkness: once they are, the Milky Way will be visible; it runs from NE to SW and should be clearly visible to the naked eye as a long, glowing streak.
22 Sept: September Equinox. The Sun is directly above the equator at midday. This marks the first day of Autumn in the Northern Hemisphere.
23 Sept: I shouldn’t have to say this, but despite whatever the latest conspiracy theory is you’ve read this time on the internet (some gibberish about the constellation of Virgo and the Book of Revelations), I guarantee the world will not end on the 23rd of September 17. Don’t believe me? Bet you $1000 it won’t. Not so confident now, are you? I’ll collect my winnings on the 24th, ta.
24 Sept: See, I told you so. Still here. These Armageddon conspiracy theories really piss me off, because when I google “September 2017 astronomy”, seven of the top ten hits are from some biblical study group telling me that if I read Revelations backwards and take every seventh word and multiply it by some random prime number it’ll correspond to the date and the stars and OH FUCK OFF. You can find patterns in Harry Potter if you look hard enough, it doesn’t make it true. (Further to that one specific complaint, I’m also pissed off that google auto-completes to “September 2017 astrology”, but that’s a whole other astro-rant). The mythical non-existent planet Nibru (which does not exist and will not hit us on the 23rd) can sod off too, and if anyone mentions that sad little internet hoax I will slap them with an astrophysics textbook. The reason it can sod off, and keep sodding off, is that if a (non-existant) planet were going to hit Earth on the 23rd, YOU WOULD BE ABLE TO SEE IT BY NOW BECAUSE IT WOULD BE BIGGER THAN THE SODDING MOON AND VISIBLE DURING THE DAY. Bearing in mind, I’m writing this at the end of August. You couldn’t see it then, won’t see it now. Don’t make me do the maths on the visibility of planet sized objects in the solar system, because I will.
26 Sept: After sunset, Saturn will be below the crescent moon. Saturn is easily visible to the naked eye; with a pair of small binoculars it looks like it has funny little ears, which is exactly how Galileo Galilei described the rings when he saw them for the first time. With a small telescope, you can clearly see that it’s a distinct ring system. Now is the time to see them.
27 Sept: Moon 3 Degrees North of Saturn. This makes Saturn easy to find, and the moon is still new enough to pose no light pollution worthy of the name.
28 Sept: First quarter moon. Now is a good time to view the Moon, as long shadows are cast on its surface, highlighting the mountains and craters. Take a set of binoculars or a small telescope. Take a map and try and find the Apollo landing sites!
That’s all for September. Go outside! Look up!