Solar analog (–0.21) for solar twin. 16 Cygni B is sometimes noted as twin, but is part of a triple star system and is very old for a solar twin at over 9 Gyr. Another way of defining solar twin is as a "habstar" — a star with qualities believed to be particularly hospitable to an Earth-like planet. Qualities considered include variability, mass, age, metallicity, and close companions. The requirement that the star remain on the main sequence for at least 3 Ga sets an upper limit of approximately 1.5 solar masses, corresponding to a hottest spectral type of F5 V. Such
Wonders of the Solar System Wonders of the Solar System Wonders of the Solar System is a 2010 television series co-produced by the BBC and Science Channel, and hosted by physicist Brian Cox. "Wonders of the Solar System" was first broadcast in the United Kingdom on BBC Two on 7 March 2010. The series comprises five episodes, each of which focuses on an aspect of the Solar System and features a 'wonder' relevant to the theme. The series was described as one of the most successful to appear on BBC Two in recent years. An accompanying book with the same name was also published. On