Cosmic Distances on a Human Scale

Exploring the light magnitudes of stars. 

Deep-space distances are so enormous that familiar measures are useless. That’s why astronomers reckon by light-years — the distance that light, racing at 186,282.4 miles per second, travels from one of your birthdays to the next. The best way to link cosmic and human scales is to embrace that weirdness and think like a beam of light. The nearest bright star visible from northern locations (Sirius, blazing in the southwest after sunset this month) lies just 8.7 light-years away. The ...

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