Sen—I'm sad to report that after all the build up and nail-biting anticipation I didn't see the solar eclipse on March 20th. Well, that's not strictly true; I saw it for a grand total of twenty seconds... in two or three second bursts... Yes, after a gloriously sunny Thursday, and a day before an even more gloriously sunny Saturday, eclipse day was dull, grey and misty, and the 500 or so people who gathered at my astronomical society's "Eclipse Watch"—including kids from local schools and a BBC radio crew which came to broadcast the eclipse live with us—caught just the barest glimpses of the Moon covering the Sun. Of course, half an hour after Last Contact the clouds ripped open like soggy tissue paper and the Sun came streaming through.
Typical. Sometimes I really hate astronomy, you know?
And to be honest, there's not a lot on the horizon to lift my spirits after the Eclipse That Never Was. At this time of year the Milky Way is essentially just a long, misty cloud hovering above and parallel to the horizon; my first sighting of "NLC"—the beautiful silvery-blue noctilucent clouds I hunt on every clear night in summer—is still months away, and there are no bright comets on the way which might replace the fading Comet Lovejoy, which I have been following since before Christmas.
Comet Lovejoy taken with an iOptron star tracker and a DSLR camera on March 28th, 2015. Image credit: Stuart Atkinson
Time to look at the bigger picture, I think, and Spring (in the northern hemisphere, where I live) is the best time to do that, because the northern hemisphere Spring sky offers the beginner astronomer the opportunity to not only see some of the most distant and beautiful objects in the sky, but also to grasp their place in the universe...
Unlike many of my football-obsessed classmates, as a quiet, library-haunting space-mad kid I used to love writing my address on the front of my exercise books because it gave me an opportunity to (over?)indulge my love of space. I proudly—and ok, maybe a little smugly—wrote out my full address on the heavy paper covers in a very deliberate order: name, house number, street, town, county, country, continent, planet, galaxy, the Universe!
Anyone reading do this when they were younger? No? Ok, just me then!
Anyway, what started out as (I thought!) just a fun thing to do turned into a bit of an obsession for me as I grew older. I became fascinated by our precise location in space, not just in our little part of the Universe but in the whole Universe. As the years passed and my astronomy knowledge grew I learned that our galaxy, the Milky Way, is just one of a group of galaxies called—rather unimaginatively, I've always thought—"The Local Group", and that group belongs to a cluster of 1000s of galaxies, which itself is part of a Supercluster containing countless millions of clusters of galaxies, which itself is just one fleck of light in a froth of Superclusters... and gradually, over the years, as PC screens replaced the exercise books and I began to write books of my own, in my head, and heart, my home address steadily grew in both length and detail.
Now, finally, some (cough cough) years after leaving school, I know my cosmic home address so fully I give an illustrated talk about all this, entitled "Home". Now I can share with other people how it feels to stand outside on a clear, starry Cumbrian night and actually sense our place in it all. I can see, in my imagination, that our Milky Way is like one glittering snowflake in a blizzard, with other snowflake galaxies stretching off in all directions to infinity. That's incredible.
But even more incredible, I think, is that astronomers have mapped not just our Galaxy's place in the wider universe, but mapped its own structure.
Of course, for many years science fiction fans have been doing this: Star Trek, Babylon 5 and HALO fans are just some of the SF tribes who have made imaginary maps showing the Milky Way split up into the various zones and sectors referred to in their franchises, but we now have detailed charts of the real Milky Way, showing its curving spiral arms, its bloated, ancient nucleus, and the halo of firefly stars around it. When I started doing astronomy outreach, just after the Big Bang, I thought it was unbelievably cool to be able to show a picture of the Milky Way with its spiral arms labelled. Now I can show my audiences incredibly detailed maps, showing our Solar System's location in the Milky Way. It turns out the Sun is within a "spur" of stars connecting two of the Milky Way's major spiral arms, each with its own frothy tendrils and glittering streams of stars.
The sheer scale of our home galaxy is incredible, too. You will have read again and again how our galaxy is 100,000 light years across, but numbers can't ever put across its truly ridiculous size, so imagine this: if our whole Solar System was shrunk so it fit into a coffee cup, on the same scale the Milky Way would be the size of North America!
If our Solar System shrank to fit in a cup of coffee. Image: Stuart Atkinson
I know, does your head in, doesn't it?
Just think about that for a moment... 17,000 years ago the cave-dwellers of Lascaux in France drew a crude picture of the Pleiades on their cave wall—an early star map. Today we have a labelled, "You Are Here" scale map of our whole Galaxy, and can virtually fly around it, under and over it in 3D on our smartphones.
Sometimes I really love astronomy, you know? But what has all this got to do with the Spring sky?
Let's just recap a little. The Sun is a star, just one of an estimated two hundred billion stars grouped together in an enormous catherine wheel of stars, a gakaxy known as the Milky Way. And that starry wheel is spinning, turning like the 2001 space station once every 240 MILLION YEARS.
When the Sun has set, all the twinkly stars we see after dark are just the Sun's nearest neighbours, and if you know where to look, beyond those stars, through the veil of suns around us, you can actually see other galaxies glowing softly, many millions of light years from the Milky Way, looking like tiny misty smudges.
And the good news is that Spring in the northern hemisphere is one of the best times of the whole year to see some of these other galaxies in the night sky. At this time of year, for example, the constellations of Virgo and Leo are putting on a fine display, high in the south east after midnight, and those two constellations are literally spattered with galaxies. If you have a good telescope you can slew it around towards those star patterns on any clear Spring night in the north and see dozens of galaxies through its eyepieces. Experienced observers with telesopes the size of cannons love to hop between them, one after another, drinking in the subtle beauty of their misty spiral ams and glowing centres. But even if you just have a humble pair of binoculars you can still find a few galaxies at this time of year, and I'm going to show you where four of them are—not in Virgo or Leo, but in or around Ursa Major, using the stars of The Big Dipper as your guides. So, if you live somewhere in the world where the stars of the Big Dipper twinkle in the sky - even if they just clear the horizon - this is for you. If you live somewhere on the planet where the stars of Ursa Major never clear the trees, well, my apologies, but keep reading, we'll have something for you later...
But before we go any further it's important for you to understand that you will NOT be seeing anything like this through your binoculars:
Image credit: NASA, ESA, The Hubble Heritage Team
Why? Because that's a portrait of the galaxy NGC1300 taken by the Hubble Space Telescope—a multi-hour exposure taken through one of the most sophisticated scientific instruments ever built by our species. High above Earth, without any murky, cloud-curdled atmosphere to peer through, Hubble can take incredibly detailed and colourful images of incredibly faint objects incredibly far away. Your binoculars can't hope to compete with that! So you will be looking for tiny, roundish greyish smudges, not the glorious pinwheels of blue, red and gold shown on Hubble photos! But that's not the point. As with so much of astronomy, the point is you will be finding and seeing something amazing for yourself, just from your own garden, or a park, or wherever you go to look at the night sky. So, none of the galaxies you're going to see—and you ARE going to see them—will look spectacular, or take your breath away, but when you find them you will find yourself smiling, maybe even shaking your head in disbelief, as you realise just what you're looking at.
Ok, let's get started.
First, you will need to find the Big Dipper, or The Plough, if you prefer to call it that. That's almost embarrassingly easym if you live in the northern hemisphere - just go out after dark, face the north east, look halfway up in the sky, and there it is, The Big Dipper, a big spoon of stars balanced on the tip of its handle. It's the stars making up that handle which will guide us to the first of our galaxies.
The Big Dipper high in the NE after darkness falls. All starchart images created with Stellarium
Hubble Space Telescope of M51
M51 is one of the favourite objects in the sky of many astronomers, and its nickname, "The Whirlpool Galaxy" gives a not-too-subtle hint about its appearance; it is a big spiral galaxy, displayed face-on to us. M51 is easy to spot in binoculars and is a wonderful sight in any telescope, large or small. To find it, you need to aim your binoculars at the star on the very end of the Big Dipper's handle, "Alkaid", then slowly, slowly, move them to the upper right until a fainter star appears in their field of view. This is "24 CVn", a star in the constellation of Cannes Venatici ("The Hunting Dogs") and it's only important because it represents the half-way point on our short trip from Alkaid to M51. Continuing to move right, dropping down a little, slowly, you will suddenly see - or rather, sense - a small, blurry, out of focus "something" in your binoculars. You'll probably go too far and too fast the first few times you try and find M51, don't worry, that's all part of the learning curve.
Look for M51 just off the end of the Big Dipper's handle
Go slowly, slowly, until... Yes, that's it, that's M51.
How to "star hop" from Alkaid to M51
Now, when you see M51 you will have one of two reactions. You'll either jump straight to "Wow! That's amazing!!!" or will let out a deep, disappointed sigh and think "Huh... is that IT???". Well, reality check time. That is often, I'd probably go so far as to say usually, the way amateur astronomy works. What you see, after lots of anticipation and build-up, after reading about something and drooling over gorgeous pictures of it for years, is nothing like what you were expecting. And that's definitely true of M51: on photographs it is a jaw-droppingly beautiful whirlpool of stars, gas and dust, with its longest spiral arm attached to a second colourful cloud of stars, which is why M51 is what astronomers call an "Interacting Grand Design Spiral Galaxy".
Image of M51 taken by Simon White, Eddington Astronomical Society of Kendal
Through a small telescope, it is a small, elongated gray smudge, with a faint blob next to it. Through your binoculars it will just look like a large, faint, unimpressive, out of focus star. But as I said, most objects in the night sky are nowhere near as impressive as they look in photos, and we don't look at them to be impressed. No, we look at them for the thrill of knowing WHAT we're really looking at. And when you spot M51 you will be looking at a seventy four thousand light years across catherine wheel of more than a hundred billion suns, thirty million light years from Earth. That means that the light entering your eye, through your binoculars, set off thirty million years ago, in the Oligocene epoch.
There you go... your first galaxy beyond our own. Well done! As Obi Wan told Luke after he had (finally) deflected the laser bolts from the practice droid onboard the Milennium Falcon, "You've taken your first step into a larger world.” Time to find your next galaxy.
HST image of M101. Image credit: NASA/ESA
M101 is one of my favourite galaxies, and it lies on the other "side" of the Big Dipper's handle to M51. Again, Alkaid (a very useful star!) is going to be our guide. Look at Alkaid, and then look at the star next along the handle, above it. This is one of the most famous stars in the sky—Mizar, and it's famous because, as you will spot right away if you have good eyesight, it is a double star. If you can't split the pair with just your eyes use your binoculars, and you will see Mizar as a fainter star snuggled up next to Alcor. We'll look at double stars properly another time, but for now Mizar is going to help us find M101. You need to imagine Alkaid and Mizar as two points in a triangle, the top of the triangle and the bottom right star of the triangle. M101 marks the third star in this triangle, the one at its bottom left.
M101 lies off to the left of the Big Dipper's handle
So, you're going to sweep that area of sky with your binoculars, again very slowly, until you see another misty, smudgy blur. It will look a little bigger than M51 did, but fainter too. Again, if it takes you a few tries don't worry about it, that's all part of getting to know your way around the sky. Eventually you will sense M101 as a vague grey smear—that's it, your second galaxy!
M101 is a small blur in binoculars
M101 is nicknamed "The Pinwheel Galaxy" which again gives us a clue to its appearance through a telescope and on photographs taken through telescopes. It is one of the loveliest galaxies of all, I think, and its classic catherine wheel shape is apparent in even a small telescope.
Image of M101 by Jeremy Hunt, Cockermouth Astronomical Society
But although it only looks like a small smudge in your binoculars, you are looking at a galaxy that dwarfs our own. 22 million light years away, M101 contains over 1 trillion stars, and with a diameter of 180,000 light years is almost twice the size of our own Milky Way. Now, just think about that. If there are creatures living on any planets orbiting stars in that galaxy, looking in our direction, they will see our Milky Way as a smudge of light only half as large as we see their galaxy in our sky! Brings it home to you, doesn't it?
If you don't find M101 right away, or even after a few tries, don't be too mad at yourself. It is a galaxy with a low surface brightness, so you will struggle to see it if you're not under a really dark sky, somewhere without any light pollution, on a night when there's no Moon. But keep trying, it's worth it. Ok, two down, two more galaxies to go.
M81 and M82
Image of M81 and M82 by Simon White, Eddington Astronomical Society of Kendal
Our last two galaxies are, conveniently, very close together in the sky—so close, in fact, that you will see them glowing side by side as you look through your binoculars. To find M81 and M82 you need to move "up" the Big Dipper to the bowl of the spoon. Look at the map and find the stars "Dubhe" (at the top left) and "Phecda" (at the bottom right). These two stars will be your guides to M81 and M82. Draw an imaginary line between them, and then extend that line the same distance in the same direction.
You will find M81 and M82 above and to the upper left of the Big Dipper's bowl
Make a mental note of the area of the sky you end up in, and then scan that area through your binoculars, again, just going slowly, no rushing. After a few tries you will see two little smudges close together in your binoculars—those are M81 and M82.
M81 and M82 will easily fit in the same binocular field of view
M81 is the larger and brighter of the two, and is known as "Bode's Galaxy". It is another "Grand Design Spiral", in that photographs and large telescopes reveal it to be a beautiful oval of light with spiral arms sweeping away from it 11.8 million light years from us. Through your binoculars it will look like a very small smudge next to the larger and brighter M81, but it's humbling to think that that "small smudge" is some 90 thousand light years across and contains 250 billion stars.
Image of M82 by Jeremy Hunt, Cockermouth Astronomical Society
In contrast, M82 is fainter and looks a lot smaller, and will look more like a vague line of light in your binoculars. This is because we are seeing this galaxy edge on from our Solar System, which vastly reduces its apparent physical size in our sky.
M82 is actually a fascinating object. Nicknamed "The Cigar Galaxy" it is a 'starburst' galaxy where a very violent period of star formation is underway, as hinted at on this image.
Image of M82 by Jeremy Hunt, Cockermouth Astronomical Society
M82 contains around 30 billion stars, and is 11.5 million light years distant. And you can see it with binoculars. Come on, how cool is that?
And there you have it, your guide to finding four galaxies in the northern hemisphere Spring night sky. Tracking them down will take a bit of work on your part, but it will be worth it, because, just like it's a thrill seeing Saturn's rings for the first time, it really is a thrill seeing your first galaxy in the night sky. Of course, being so close to the Big Dipper means those galaxies are all northern hemisphere objects really, but if you're living in the southern hemisphere don't feel too agrieved, you have a pair of galaxies in your autumn sky which are so big and so bright you don't need to look for them, they slap you across the face as soon as you go outside! The Small and Large Magellanic Clouds are satellite galaxies of our Milky Way, and look like detached parts of it in the southern sky, and really could be mistaken for clouds if you didn't know they were massive collections of stars. Sen's news editor Paul Sutherland took this gorgeous photo of the clouds on a trip to New Zealand.
Image of the Magellanic Clouds by Paul Sutherland
At this time of the year the Magellanic Clouds hang above the southern horizon, and you really can't miss them.
Look for the Magellanic Clouds above the southern horizon after dark...
I hope that when you find these galaxies you will feel moved by the sight of them. They might only look like little smudges or blurs through your binoculars, but each one is a truly gigantic collection of billions of stars, and if current theories are correct then most of those stars will have at least one planet circling them. So, as you look at them, just take a moment to wonder how many lush blue and green worlds like Earth spin serenely around their distant suns, and how many intelligent civilisations there are on those worlds—and how many beings there are, every bit as curious as you, scanning their skies from their gardens, with their binoculars, seeing our own Milky Way as a tiny smudge through the starry veil of their own galaxy..?