RocketSTEM Issue #11 - April 2015 | Page 37

7. Hubble Ultra Deep Field is filled with galaxies Galaxies, galaxies everywhere - as far as the Hubble Space Telescope can see. This view of nearly 10,000 galaxies is the deepest visible-light image of the cosmos. Called the Hubble Ultra Deep Field, this galaxy-studded view represents a “deep” core sample of the universe, cutting across billions of light-years. The snapshot includes galaxies of various ages, sizes, shapes, and colours. The smallest, reddest galaxies, about 100, may be among the most distant known, existing when the universe was just 800 million years old. The nearest galaxies - the larger, brighter, well-defined spirals and ellipticals - thrived about 1 billion years ago, when the cosmos was 13 billion years old. In vibrant contrast to the rich harvest of classic spiral and elliptical galaxies, there is a zoo of oddball galaxies littering the field. Some look like toothpicks; others like links on a bracelet. A few appear to be interacting. These oddball galaxies chronicle a period when the universe was younger and more chaotic. In ground-based photographs, the patch of sky in which the galaxies reside (just one-tenth the diameter of the full Moon) is largely empty. Located in the constellation Fornax, the region is so empty that only a handful of stars within the Milky Way galaxy can be seen in the image. The image required 800 exposures taken over the course of 400 Hubble orbits around Earth. The total amount of exposure time was 11.3 days, taken between Sept. 24, 2003 and Jan. 16, 2004. Credit: NASA, ESA, and S. Beckwith (STScI) and the HUDF Team “There are so many, but I have two favorite images:  “1) The Pillars of Creation [#82] is an iconic photograph taken by Hubble showing a glimpse of gas and dust regions veiling new star formation. This image was taken in 1995, long before my career in astronomy took off, while I was still only in middle school. There is something mysterious and beautiful about the process by which new stars are born. “2) Fast forward a decade, into the era of Hubble Treasury programs, at which point 20-30% of Hubble’s orbits were dedicated to large observing projects. The Hubble Ultra Deep Field revealed billions of years of cosmic growth for galaxies, including detections of the most distant known galaxies.” — Dr. Katherine E. Whitaker NASA Postdoctoral Program Fellow Goddard Space Flight Center Greenbelt, Maryland