When I became a Masters student, a big part of the reason I liked the supervisor I had was that she studied M31: The Andromeda Galaxy. Since I was young I was obsessed with finding this galaxy in a telescope, and I will never forget when I first found it, seeing photons that had travelled for 2.5 Million years through space, it was my first ever experience with time travel.
So its natural that I am excited about a recent Hubble release of the highest resolution photo of the Andromeda Galaxy Ever taken. Let’s start with a standard shot of the Galaxy.
Andromeda is the closest large Galaxy to us. There are about a dozen small Galaxies nearby, but this one is the biggest Galaxy with a similar structure to the Milky Way. The Galaxy contains somewhere around 400 Billion stars. With such an astronomical population of stars (pardon the pun), it’s natural that we as humans can’t really imagine how this cloud-like object is actually made of suns.
The Hubble release gives us a real visual example of how the galaxy is composed of suns. Here is the high-res image, about 20 Mb in size:
If you clicked the picture above and saw the full size 20Mb image, you might notice that the picture has a slight grainy look to it. If we take a look at the zoom image I compiled, we can see why.
The grainy look is due to Millions of stars being individually resolved! We can finally see the true size and scale of the Andromeda Galaxy. Stars near the outer part of the Galaxy shown at right are at most 10 Light Years apart. Closer to the centre that gap closes and stars are packed even more tightly.
You might notice that as we move from right to left, or from the edge of the Galaxy to the centre, the stars become redder. This is what is actually happening. Stars closer to the centre are older, and older stars are redder. We are seeing the cloud of a Galaxy in it’s individual stars.
This is almost as if we could take a person and produce such a high resolution image of them that we could see their individual skin cells.
The full image of the Galaxy taken by Hubble is 4.3 Gb in size! It likely contains 100 Million stars within the single image. I won’t be able to post the entire thing, but I did use the full size image in my zoomed image above, so you can see just how incredible the resolution is. In some places, if you take a close look, you can see Galaxies that are behind the Andromeda Galaxy. In essence we are seeing straight through M31.
This image is in a category with others such as the ‘Pale Blue Dot’ and the ‘Pillars of Creation,’ because it gives us perspective on how small we are and how wondrous the Universe is. If you feel so inclined, download the full size image and just play around by zooming in and seeing the structures in fine detail. You may spend a couple hours on it like I did…..