It wasn’t all that long ago that I wrote a five-part series on Hubble’s old camera, WFPC2. I call it “The Camera that Changed the Universe.” Part 1 focused on Hubble showing us just how deep, rich, and full of wonder our Universe is. Let’s remember how this happened.
The first thing we did was take a patch of sky that was relatively empty. No bright stars, no large galaxies or clusters, no planetary nebulae, just a little tiny patch of black, empty sky.
And then we point Hubble at it. And what do we do? We sit there. And wait. Collecting tiny, miniscule amounts of light. First, for minutes on end. And then the minutes turn into hours, and the hours turn into days. All the while, Hubble just patiently sits there, pointing at the same patch of empty sky. Over 10 days, Hubble took a photograph of the same exact patch on the sky 342 times. They then added up the light from all 342 of these images. The result?
The Hubble Deep Field, taken by WFPC2. Every point of light in this image (except for about 6 which are dim stars) is a galaxy. Thousands upon thousands of new galaxies were discovered. Some were only a few million light years away, others were over ten billion light years away. All told, we learned that there are at least one hundred billion galaxies in our Universe. And we learned it from this single photograph.
Well, nearly a decade after this, they installed a new, better camera, called the Advanced Camera for Surveys. And to one-up the Hubble Deep Field, they picked a different blank patch of sky, went even deeper, and created the Hubble Ultra Deep Field. Take a look:
There are approximately 10,000 separate galaxies in this tiny little piece of sky. Well, the good folks at NASA and the ESA have created a 3-D flythough simulation of the image, showing you what it would look like if you actually flew through this image! Now that you know how distances work in cosmology, all they had to do was measure the redshift of each galaxy and program it in. Tony Darnell narrates it, and I’ve embedded it for you right here! (You can start at the 2:53 mark if you want to skip the intro.) And remember, as you watch it, that each dot of light in this image is a galaxy, comparable to our own Milky Way, with nearly a trillion stars, only one of which is our own Sun.