How does man specify interstellar distances when using the speed of light?

Answer 1

Our common terms for distance, miles and kilometers, are useful enough to measure distances around town, and even around the country. But for distances beyond our solar system, it's cumbersome to carry around a bushel-basket full of zeroes to add to the distance measurements.

So we typically phrase things in terms of "light-years", the distance that light would travel on one year. Light moves at 186,000 miles or 300,000 kilometers per SECOND, so a light year is quite a distance; 186000 * 60 * 60 * 24 * 365.24 miles, which is 5,869,552,900,000 miles. The nearest star, Proxima Centauri, is four times FURTHER away at 4.2 light-years, so you can see that the distances to even the nearer stars are quite cumbersome when expressed in conventional units.

In metric terms, we have, perhaps, another way to go. The standard distance is the "meter", and latinate prefixes are used to denote larger quantities, such as the kilo-meter, for 1,000 meters; about 6-tenths of a mile.

In computer terms, the word "byte" is used to designate the storage space required to store one ASCII character. A "kilo-byte" is a thousand bytes (actually, 1024 bytes, but close) and a "megabyte" is a million (plus a bit) bytes. A gigabyte is a billion, and a terabyte is a trillion.

So, let's extend that to astronomy. One light year is 5.8 tera-miles.

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