Hubble Deep Field: How a Photo Revolutionized Our Understanding of the Universe
Chapter One BOLD HUNT FOR DISTANT GALAXIES Astronomer Bob Williams and his scientific team prepared to take a big risk in December 1995 a risk that could have ended Williams distinguished career as a scientist It involved taking a series of photographs Williams was keenly aware that there was great power in certain photos Still fresh in his mind was the Blue Marble a magnificent portrait of Earth taken from high above by U S astronauts in 1972 It had caught the attention of people around the globe showing that they lived on a tiny fragile sphere floating in the vastness of space
Apollo 17 astronauts snapped a photo of Earth in 1972 that became known as the Blue Marble Williams wanted to capture a very different sort of image one of an area of space extremely far away from our planet Two years before he had become director of the Space Telescope Science Institute STScI which ran the National Aeronautics and Space Administration’s Hubble Space Telescope Launched into space in 1990 NASA’s Hubble held out the promise of clearly seeing cosmic objects so distant that they appeared dim and blurry from ground-based telescopes Williams wanted to point Hubble at a tiny patch of sky near the handle of the Big Dipper in the constellation Ursa Major the Great Bear The patch covers an area as big as a grain of sand held at arm’s length The plan was to take hundreds of pictures of the target area during 10 days Sophisticated computer software would combine them into a single image The goal was almost too ambitious to imagine Williams and his team wanted to test
the outer limits of space and time We know that the speed of light is 186,000 miles 300,000 kilometers per second The light from a very distant galaxy travels at that speed So if the light has been traveling for millions of years glimpsing the object now is in a very real way seeing back in time at what it looked like when the light began its journey Williams and a small group of colleagues wanted to look for distant galaxies A galaxy is a gigantic system of millions or billions of stars Our local galaxy the one that contains the sun is the Milky Way Many other galaxies exist beyond the Milky Way Hundreds of thousands of these massive systems were detected and photographed in the 20th century The Milky Way galaxy which contains our solar system fills the night sky But astronomers had yet to determine how far into the reaches of deep space galaxies existed They also wondered when the first galaxies appeared Have they always looked like they do today or have their shapes evolved over time And will they along with the universe itself go on expanding forever Williams and his team hoped that photographing some very distant galaxies might allow them to begin to answer some of
