In 2004, NASA released the Hubble Ultra Deep Field. This image of a small part of the constellation Fornax contains around 10,000 galaxies, some of which existed 13 billion years ago, less than 800 million years after the big bang. Snapshots like these allow scientists to study galaxies at different evolutionary stages. It’s a bit like taking a picture of all the people in New York City’s Times Square and using it to study human aging, since it would show examples of people of all ages. But even with all our modern observatories, astronomers still have many questions about exactly how galaxies begin and grow.