What is a lightyear?
A lightyear is a unit of measurement used in astronomy to describe vast distances in space. It represents the distance that light travels in one year, which is approximately 5.88 trillion miles or 9.46 trillion kilometers. The term "lightyear" is derived from the fact that light, which travels at a speed of about 186,282 miles per second (299,792 kilometers per second), can cover an incredible distance in the span of a year.
Light has a finite speed, so a galaxy a billion lightyears away is seen as it was a billion years ago. That is how astronomers look back at the early universe – the farther the galaxy, the older the picture.
What is a furlong?
A furlong is 220 yards or 660 feet, which is exactly 201.168 meters. It is an eighth of a mile.
The origin of the term "furlong" can be traced back to Old English, where "furh" meant "furrow" and "lang" meant "long." This reflects the historical use of furlongs in measuring the length of a furrow in agricultural fields. In horse racing, furlongs are used to measure the distance between the starting point and the finish line. A racecourse typically consists of multiple furlongs, with the most common distances being 5 furlongs (5/8 of a mile) and 8 furlongs (1 mile).
Outside the racecourse the furlong has almost gone. British racing still gives distances in miles and furlongs, so a mile and a quarter is written 1m 2f. Road signs don't use it – they give miles and, for short distances, yards.