They will see us waving from such great heights
“Come down now,” they’ll say.
But everything looks perfect from far away
“Come down now,” but we’ll stay. –Postal Service
We’ve been over this twice before, but here’s a refresher on how you image the farthest galaxies in the Universe. Pick a spot in the sky that’s empty. What does empty mean? When you look with your eyes, with binoculars, and even with a reasonable telescope, you find no bright stars, no bright galaxies, no nebulae, no clusters — in short nothing — except for the absolute faintest of objects.
You know, something like this substantial region, which has maybe six ultra-dim stars in it. (Which is a tiny, tiny number for a region as big as this.)
You then take the most powerful “picture-taker” that you have. For astronomy, that means the most light-gathering power (or largest mirror), the least atmospheric distortion (or, ideally, no atmosphere), and the best camera possible. Where do we go for the best combination of all three?
Well, we go to the Hubble Space Telescope! Years ago, with the old Wide-Field-Camera, Hubble took a look at this region, and just left the shutter open on the same region of the sky, taking picture upon picture of the same exact place. They then added the light from all of those images together, and produced an image known as the Hubble Ultra Deep Field (HUDF). It looks like this.
Fast-forward to the present day. Now, we’ve got the same light-gathering power, the same lack of atmosphere, but a brand new camera! This time, they used an infrared filter (instead of a visible light composite), and took a picture using the same exact method. First off, here’s the result.
I don’t want to just leave you these images, I’d like to show you the same exact regions on both of them, zoomed in, so you can really see the similarities and differences; they’re really interesting. So, here you have a few of my favorite excerpts.
versus new image…
and again with the old image (with a star, this time)…
and again with the new image (with the same star)…
and once last time with the old, in a long strip,
and finally once more with the new, in the same strip!
No words for how magnificent these images are. And — just as a reminder — this whole entire Ultra-Deep-Field image only views about one-one hundred thousandth of the sky! I could play with these all day long, but then where would the fun be for you? Download the ultra-high resolution versions of the old image and the new one, and go play yourself!