Article I, Section 8, of the Constitution, which enumerates the powers of Congress and provides Congress with the authority to make all laws necessary and proper to carry them out; also referred to as the elastic clause.
There is an exact numerical answer to this question. By definition, 1 light year is exactly 9,460,730,472,580,800 meters. By definition, 1 mile is exactly 1,609.344 meters. So, 1 light year is exactly 5,878,625,373,183 and 849/1397 miles, by definition.
300 000 kilometers, which equals seven times around the Earth. Let's call this distance one light second. We can use this as a ruler to measure distances in space. Beyond the Sun and its planets we need a longer ruler, which is the distance light travels in one year. This is called a light year - it is 32 million times longer than a light second. Multiplying a light second by the number of seconds in a year, we can answer the question: How far is a light year? 10 trillion kilometers (or more exactly, 9.5 x 1012 km).