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Curt Nason

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Early next year the Hubble Space Telescope will receive its fifth visit from NASA space mechanics. Since its launch in 1990 The Hubble has done much for the advancement and popularity of astronomy, just as its namesake increased our knowledge of the night sky eight decades ago.

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The Hubble Space Telescope’s orbit at 600 kilometres allows it to take astrophotos of unprecedented detail.

Born in Missouri in 1889, Edwin Hubble obtained his PhD in astronomy at the University of Chicago and, at the age of 30, began a career at Mount Wilson Observatory. Using the Hooker Telescope, the world's largest with a 100-inch-diameter mirror, Hubble was able to detect individual stars in photographs of the Andromeda spiral nebula. He discovered some stars were variables of a type for which Henrietta Leavitt had devised an equation to determine their brightness. He applied her formula and calculated that the Andromeda Nebula was almost a million light years away, confirming spiral nebulae were not part of our Milky Way galaxy. The universe was suddenly much larger than anyone had thought.

Over the next several years, Hubble used various methods to estimate the distances to thousands of galaxies and classified them according to their shapes in the photographs. He and Milton Humason measured changes in their spectra, called the red shift, and compared the galaxies' red shifts with their estimated distances. They found that the farther a galaxy was, the faster it was receding from us. One twice as far as another was receding at twice the speed. This expansion of the universe like an inflating balloon was the first observational evidence of the recent Big Bang theory. Hubble and Humason derived a value, later to be called the Hubble Constant, which would be used to determine the distance to a galaxy by measuring its red shift.

Edwin Hubble continued working at Mount Wilson and became the first to use the 200-inch Hale Telescope on nearby Mount Palomar in 1948. His stature and fame had him rubbing shoulders as a man of society with the Hollywood elite. From his early years at Oxford as a Rhodes Scholar, he affected a British accent and a preference for tweed and knickers that occasionally irked his colleagues, and spent many summers fishing the streams of England. Hubble died suddenly of a stroke in 1953 and only his wife and a few others knew the location of his cremated remains.

Refinements were made to the size of the universe since Hubble's death, and two opposing camps arose over the value of the Hubble Constant. Knowing this value would give the age of the universe, and the opposing camps had estimates of about 10 to 18 billion years. Bending of light by Earth's atmosphere, the reason why stars twinkle, limited the usefulness of ground-based telescopes in obtaining measurements of the most distant, and hence oldest, galaxies. The space telescope was conceived to eliminate that hindrance.

Despite having a mirror slightly smaller than that of the Hooker, the Hubble Space Telescope's orbit at 600 kilometres allows it to take astrophotos of unprecedented detail. Using data from this and larger ground telescopes, astronomers discovered that the expansion of the universe is accelerating. The Hubble Constant has been refined to a value comfortably between those measured by the two opposing groups, and the time since the Big Bang has been determined to be 13.73 billion years, give or take a mere 120 million.

Next year's servicing mission of the Hubble is likely to be its last, allowing it to advance our knowledge of the night sky for several more years until the James Webb Telescope is launched. I will be checking the classified ads for a used 2.4-metre telescope, cheap, pick-up only.

The Saint John Astronomy Club meets on the first Saturday of the month. Contact Curt Nason (648-9063, nasonc@nbnet.nb.ca) or visit their website at http://sjacnb.tripod.com.