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The light-minute is a unit of length useful in astronomy, telecommunications and relativistic physics. It is defined as the distance that light travels in free space in oneminute, and is equal to exactly 1.798754748×1010 metres.
The spat (symbol S) is also an obsolete unit of distance used in astronomy. It is equal to 1000000000 kilometres (1 Tm or 1012 m). It is about 6.6846 astronomical units (AU), 1.057×10−4 light-years or3.240×10−5 parsecs.