Light-year Light-year The light-year is a unit of length used to express astronomical distances and measures about 9.46 trillion kilometres or 5.88 trillion miles. As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year (365.25 days). Because it includes the word "year", the term light-year is sometimes misinterpreted as a unit of time. The light-year is most often used when expressing distances to stars and other distances on a galactic scale, especially in nonspecialist and popular science publications. The unit most commonly used in professional astrometry is the parsec
Kwangmyŏngsŏng-3 Unit 2 launch of Kwangmyŏngsŏng-3 Unit 2 was the fourth North Korean attempt to orbit a satellite, and North Korea claimed that two of the previous launches had placed their payloads into orbit despite several other countries confirming that the launches had failed, and no independent confirmation that the satellite was in orbit. The first attempt occurred in August 1998, with a Baekdusan carrier rocket attempting to launch Kwangmyŏngsŏng-1; the second occurred in April 2009 with Kwangmyŏngsŏng-2, and the third in April 2012 with the original Kwangmyŏngsŏng-3. The April 2012 launch was the only one which North Korea acknowledged to have failed.