If someone were to ask you how far you would be able to see with the naked eye unaided, what would your answer be? A couple of miles, at best? Well, the answer is actually 14,696,563,432,959,020,000 miles - that's 14.7 quintillion miles. This is because it is possible for anyone to see, with the unaided eye and without the use of a telescope or binoculars, our nearest neighbour galaxy - the Andromeda Galaxy, which is about 2.5 million light years from us.
Now, it would have to be a really clear, dark, moonless sky for you to see it. And even then, all you'd probably see would be a faint smudge. Even with a small telescope such as mine, you'd be able to make out it's shape but it would still appear as a fuzzy white patch in the sky. But just the thought that you are looking at a patch of light that took two and a half million years to reach you and is many quintillion miles away - well, that just blows my mind! And you're not just looking at another planet or star - that is a whole new galaxy, just like our own Milky Way! Below is a photograph I took of Andromeda last night, over the northeastern skies of Longstanton - my first photo of a galaxy! It;s that fuzzy cloudy 'star' near the centre of the picture.
While the Andromeda Galaxy is pretty easy to see in a telescope, because it is just a fuzzy patch, taking the photograph above was deuce difficult. CCD cameras for small telescopes are also called lunar planetary imagers - which means they're primarily designed to capture images of the moon and a few planets. To capture stars, they'd have to be pretty bright - at least magnitude 5 or less. So fuzzy patches would be impossible. I had to use my Olympus Camedia C4040Z digital camera afocally with the eyepiece. To get decent pictures of fuzzy deep sky objects with a camera, you'd need long exposures - typically, at least a few minutes. My ancient C4040Z unfortunately has a maximum exposure time of just 16 seconds. To make up for the lack of long exposures, I squeezed as much wide aperture as I could out of the camera (1.8) and used the maximum ASA available (400). There was quite a bright crescent moon out as well, and I was observing about an hour before dawn, so seeing conditions were far from ideal.
Now, if I had a telescope such as the WIYN 0.9-meter telescope at the Kitt Peak National Observatory in Arizona, I would not need all the fuffing about with exposures, apertures and film speeds. The picture of the Andromeda Gakaxy below was taken by the WIYN 0.9-meter telescope. And just to give you some perspective of the size of that - that telescope's 12 times bigger than mine, has banks of CCD imagers built into it and cost half a million US dollars!
Andromeda is not only the closest galaxy to the Milky Way - it's also moving closer to us every day! Andromeda and our Milky Way are hurtling towards each other at about 70 miles per second. But before you have sleepless nights fretting about alien suns and planets crashing into your garden shed one night, astronomers estimate that this galactic collision with Andromeda will probably take place about 5 billion years from now. By that time, our Sun would have swollen into a red giant and swallowed up the inner Solar System planets, so Earth will have other things to worry about!
