The hubble extreme deep field

So the story goes - the Director of the Hubble Space Telescope is allowed time each month to use the telescope to observe whatever s/he likes (incidentally, if you wanted to know why NASA doesn't point the thing at Earth just for fun, the reason is simple: the Earth spins below the orbiting Hubble way too fast . So you'd get worthless blurry looking pictures). So back in 1995, five years after the Hubble was put into orbit, the director at the time (Robert Williams) pointed the telescope at a particularly dark and tiny region of the sky (about a quarter the size of the full moon = 1/28,000,000th of the whole sky) and left the thing to stare into deep space for a couple of days in total (Hubble orbits the Earth of course so it took hundreds of photos of the same patch of sky over the course of many orbits). The picture thus assembled became known as the Hubble Deep Field (HDF) and is now old news in the astronomy community - but one of the most famous pictures of all time. What some don't know is that the process has been repeated a couple of times since with the Hubble Ultra Deep Field and in 2012 the Hubble Extreme Deep Field (XDF).

In all cases, what was seen were thousands of specks of light. Each speck - an entire galaxy. THE XDF is an even smaller patch of space than the HDF. The XDF is less than half the size of the HDF and so maps a region of space smaller than 1/56,000,0000th of the whole sky. That's a tiny patch of sky. Yet in that sky, the Hubble Telescope was able to resolve something like 5,500 individual galaxies. The XDF image actually also contains two spots that are actually stars within our own galaxy (we can tell the difference because of spectral analysis of their light - I write a bit about spectral analysis in another post).

So how does something like the XDF make you feel? Given there's 5,500 galaxies in a region of sky just 1/56,000,000th of the whole -  in theory, Hubble could see at least 308 billion galaxies (if there weren't other things in the way - like our galaxy and nebulae and so on). And the Hubble isn't even a particularly large telescope (consider that Hubble has a 2.4 meter mirror for collecting light, compared to around 10.0 meters for the biggest telescopes on Earth). My point is: with an even bigger telescope in space, you'd see far more galaxies. Do so many galaxies make you feel unimportant? It shouldn't.

Who cares about huge numbers of galaxies? There's huge numbers of sand grains too - and in each sand grain there's more atoms than there are galaxies than Hubble can see (by a factor of trillions). So big numbers just don't matter.

Consider a small number: 1. In all our searching we've found billions upon billions of galaxies but we've found only one place with life and one place which is looking outwards into space. So far as we know, we're the only ones trying to understand what's out there and how it works. So perhaps that should make you feel big and important.