The oldest galaxy ever seen: Looking back in time with Hubble

The Hubble Space Telescope | Image: NASA It’s a well-known fact among astronomers that if you look at the Sun, you are looking back in time – fast as light is, it still takes 8 minutes to travel those 93 million miles. Likewise, when you look at the Moon, you are actually seeing it as it was 1.3 seconds ago, not as it is right now. So imagine looking at something so far away that its light took 13 billion years to reach us – that would mean we would be looking back in time 13 billion years, back to just after the dawn of time.

Well, NASA scientists using the Hubble and Spitzer Space telescopes have done just that, imaging one of the first ever galaxies to exist (see image below). Without vital pioneer galaxies like this one, our own Milky Way galaxy would not exist today.

Look inside the square and circles for the 13 billion year old galaxy | Image: National Geographic / NASA

So how is it possible to see so far back in time? It’s all down to a clever trick known as gravitational lensing. Basically, when you have a big object such as a galaxy, Einstein’s theory of relativity says that it will bend everything toward it sightly – light included.

The light from the 13 billion year old galaxy (A1689-zD1) was bent toward a second galaxy that is much closer to us, and this not only distorted the original galaxy’s light, but also made it appear much bigger.

In this image it is only possible to see the main bands of stars in the ancient galaxy. But get this: by 2013, when the James Webb Space Telescope (Hubble’s mega-successor) is launched, we will be able to resolve individual stars in this galaxy, even though it is so far away. And we will be able to see even further back in time, to galaxies even older than this one.

Hyakutake1957 has written a fascinating post with even more detail over on his blog.