Speed of light they appeared 13 billion years ago, when the universe was less than a billion years old. The fact that more distant objects appear to be younger, due to the finite speed of light, allows astronomers to infer the evolution of stars, of galaxies, and of the universe itself. Astronomical distances are sometimes expressed in light-years, especially in popular science publications and media. A light-year is the distance light travels in one year, around 9461 billion kilometres, 5879 billion miles, or 0.3066 parsecs. In round figures, a light year is nearly 10 trillion kilometres or nearly 6 trillion miles. Proxima Centauri,
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.