Tuesday, 9 November 2010

Looking back in time: The Ultra Deep Survey

Image courtesy of the UDS team

A couple of weeks ago I wrote about our upcoming move to "Minimalist Mode" and also how I'd be on the summit while we switch to remote observing. Omar, one of the people I first supported at UKIRT, will be there as well which is fitting, because his research team have just released some stunning data based on data taken at UKIRT.


The UKIRT Infrared Deep Sky Survey (UKIDSS) has been running for five years now and has produced some fantastic data, yet despite not being an extragalactic astronomer, of the five sub-surveys we've been running, Omar's Ultra Deep Survey (UDS) is the one that has attracted my interest the most (although the Galactic Plane Survey (GPS) is the most fun to actually observe since even the raw images are beautiful!).

The UDS team have recently released some stunning images at their website in Nottingham. The top one of the two is the most interesting I think (it includes optical data taken at the Subaru Telescope as well as infrared data taken at UKIRT) and at first glance doesn't look particularly impressive, but start zooming in and moving around the field. Almost everything in that field is a galaxy and as a rough rule of thumb, the redder the galaxy the further away it is. Due to the expansion of the universe, light from distant objects is "redshifted" or expanded making it look more red. The further away a galaxy is, the faster it's moving away from us, the more the lights is stretched and the redder it looks. Bear in mind that for most of the galaxies in this image, their light started off on a journey to us before the Earth was even formed 4.5 billion years ago. Light from several hundred of the galaxies in the image started their journey roughly 13 billion years ago, not long after the universe was formed. The numbers are impossible to imagine. Only the US deficit is harder to picture.


What I find even harder to comprehend is the enormous scale of the universe. Next time you're outside at night and the moon is up, hold a penny between your fingers and at arms length hold the penny up against the moon. It's roughly the same size, yes? That's also the approximate size of the UDS field. Now, think about how many pennies you'd have to hold to cover the whole sky. Remember, there's also a whole hemisphere below you as well, so multiply your guess by two!

If you had superman-like eyes, in every one of those penny-sized patches of sky you would see the same thing - countless galaxies in each patch. Maybe the mind-boggling size of the universe will become apparent. Unfortunately, it hasn't done so to me yet. I think my brain is too small.


gigi-hawaii said...

I guess the only way to comprehend the vastness of the universe is to go above the clouds. Usually, I cannot see the stars because of low clouds.

Too bad there is no airplane with a glass ceiling!!! I would love that, because then I would not suffer from the thin air on Mauna Kea.

Tom said...

Not quite a glass roof, but close! NASA - Sofia.

I very nearly applied for a job there a couple of years ago!


Keera Ann Fox said...

What Gigi said. I live in a city that has so much cloud cover and light pollution, I have given up trying to see anything but the brightest stars.

I won't even try to wrap my brain around "billions and billions of pennies" (to paraphrase Sagan :-) ). But I love the idea of it.