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
Terra: The Nature of Our World Award and a WEBBY Award in the Green category. As - TERRA: The Nature of Our World—lifeonterra.com was a finalist at the 2008 Wildscreen Film Festival in Bristol in the "New Media" Category. As - TERRA: The Nature of Our World—lifeonterra.com was a Finalist at the 2007 SxSW Interactive Festival in the Student Category. As - TERRA: The Nature of Our World-lifeonterra.com won the 2007 Webby for Student Online Film and Video ². As - TERRA: The Nature of Our World—lifeoneterra.com was a finalist at the 2007 Jackson Hole Wildlife Film Festival in the 'Best use of New Media Category'.