Distant Dubhe

StarDate: June 13, 2009

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1885 was a year of grand accomplishments. President Chester Arthur dedicated the Washington Monument, and the Statue of Liberty arrived in New York. Louis Pasteur successfully tested his new rabies vaccine on humans. Leland and Jane Stanford established Stanford University. And in London, Gilbert and Sullivan opened a new opera -- "The Mikado."

All of these accomplishments are still with us today. And so is another reminder of the year 1885: the light from a distant star.

Dubhe marks the outer corner of the bowl of the Big Dipper, which is in the northwest this evening. As you look at the star tonight, you're seeing it as it looked in 1885, because Dubhe is 124 light-years from Earth.

The light-year is the distance that light travels in one year.

Light zips through space at 186,000 miles a second. Even so, it takes about eight minutes to travel from the Sun to Earth. Yet that's not even a baby step compared to the distances to other stars.

In a day, light travels about 16 billion miles -- but that barely gets you beyond the realm of the planets. In a year, it covers six trillion miles -- but that's only a quarter of the way to the nearest star system.

At 124 light-years, Dubhe is almost 750 trillion miles away -- and it's a close neighbor. With such big numbers, it's not surprising that astronomers came up with a longer unit for measuring the distances to the stars: the light-year.

Script by Damond Benningfield, Copyright 2009

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