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Professional [[astronomer]]s prefer to use the [[parsec]] (approximately 3.26 light years) instead of the light year.

Professional [[astronomer]]s prefer to use the [[parsec]] (approximately 3.26 light years) instead of the light year.

The light year is easily derived from the speed of light which is about 300,000,000 meters per second = <B><math>3x10^8</math></B>m/s.

The light year is easily derived from the speed of light which is about 300,000,000 meters per second = <B><math>3\times10^8</math></B>m/s.

A light year can then be calculated to be about <math>3.00x10^8</math>m/s times 3600s times 24 times 365 = <B><math>9.46x10^{12}</math></B> kilometers, or <B><math>5.9x10^{12}</math></B> miles (5900 billion miles).<br>

A light year can then be calculated to be about <math>3.00x\times0^8</math>m/s times 3600s times 24 times 365 = <B><math>9.46\times10^{12}</math></B> kilometers, or <B><math>5.9\times10^{12}</math></B> miles (5900 billion miles).<br>

(To put this in perspective: a person would have to live 31 years, 251 days, 7 hours, 46 minutes, and 39 seconds to reach the age of '''1 billion''' seconds-old.)<ref>http://mathforum.org/library/drmath/view/58739.html</ref>

(To put this in perspective: a person would have to live 31 years, 251 days, 7 hours, 46 minutes, and 39 seconds to reach the age of '''1 billion''' seconds-old.)<ref>http://mathforum.org/library/drmath/view/58739.html</ref>