Hubble Deep Field: How a Photo Revolutionized Our Understanding of the Universe
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
these questions Hubble’s camera pointed near the handle of the Big Dipper a star pattern in the constellation Ursa Major the Great Bear Using Earth-based telescopes that little piece of space in Ursa Major appeared to be mostly black and empty of cosmic objects It contained a few stars known to be in one of the Milky Way’s outer arms Telescopes had also detected a handful of tiny blurry blobs of light in the target region which might be galaxies But if so there were not many of them Otherwise the area Williams had singled out seemed to be composed mostly of empty space Considering these facts several of Williams fellow astronomers felt that devoting 10 days of Hubble’s time to such a venture might be a serious mistake There was wide agreement that every minute of Hubble’s time was scientifically valuable even precious What if after the 10 days Williams proposed photo showed mostly empty space Further complicating matters was the fact that Hubble already had gained a reputation for not living up to expectations Not long after the telescope’s launch its
first photos had been a disappointment An unexpected flaw in its mirror had caused the pictures to be blurry Astronauts repaired Hubble’s faulty mirror in December 1993 A group of astronauts from the space shuttle Endeavour had saved the day by repairing the space telescope and fixing the problem But the effort had been costly and both politicians and the public were now sensitive about projects that might waste Hubble’s valuable time Not surprisingly some of Williams colleagues urged him not to move forward with his plan Some strongly warned him that if his 10-day experiment failed it might be a public relations nightmare for Hubble and NASA One of them Lyman Spitzer Jr a physicist and astronomer was more diplomatic Bob are you sure
