The Scale of The Universe: Measuring The Cosmos

The Scale of the Universe: Measuring the Cosmos

By Mr Ghaz, February 22, 2011

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The Scale of The Universe: Measuring The Cosmos

In order to have an accurate map of the universe, astronomers must use some scale of measurements. But units such as miles or kilometers are far too small to be useful in measuring the vast distances of objects beyond our solar system.

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Instead, astronomers use the light-years, the distance that a ray of light travels in one year. Since light moves at a speed of about 186,300 miles (299,820.7 kilometers) per second, a light-year is approximately 6 million million, or 6 trillion, miles (9.7 trillion, kilometers).

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The nearest star to the sun is Proxima Centauri, 4.25 light years distant. The galaxy that contains our solar system has a diameter of about 100,000 light-years; beyond it lie other galaxies at distances of thousands of millions, or billions, of light-years away. The most distant of objects, the recently discovered quasars, are at the edge of the observable universe, 10 to 20 billion light-years away.

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Although such vast distances seem impossible for the human mind to visualize in any meaningful way, they are essential for astronomers, who must find ways to calculate these figures accurately.

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To measure the distances to other planets in out solar system or to nearby stars, a simple method derived system or to nearby stars, a simple method derived by the ancient Greeks is often used. Called the parallax method, it measures the position of a star from the earth and then takes another measurement at a later date after the earth has moved through space in its orbit around the sun.