Future Telescopes * a newly proposed Exo-Earth Imager (EEI) could show astronomers an Amazon-size forest, with its green hint of biology, on an Earth-size planet 30 light years away. *It's a bold promise, considering that NASA and the European Space Agency are still a dozen years away from even attempting a Terrestrial Planet Finder (TPF) that could barely see such worlds as tiny specks. *One NASA concept envisions a spaceborne array of 20 telescopes, each 26 feet in diameter …
showed first 75 words of 1683 total

showed last 75 words of 1683 total
…Discovered By: William Herschel Date of Discovery: 1781 Distance from the Sun: (Semimajor axis of orbit) 2,870,972,200 km 19.19126393 A.U. Radius: 25,559 km (4.007 of Earth's radius) Volume: 52 (Earth = 1) Mass: 86.849 x 1027 g Density: 1.30 gm/cm3 Surface Gravity: 869 cm/s2 Escape Velocity: 21.29 km/s Sidereal Rotation Period: 0.71833 (retrograde) Sidereal Orbit Period: 84.016846 sidereal years Mean Orbit Velocity: 6.8352 km/s Orbit Eccentricity: 0.04716771 Orbit Inclination: 0.76986 degrees Equatorial Inclination: 97.86 degrees Atmospheric Temperature (at level with pressure = 1 bar): 76 K Major Atmospheric Constituents: H2, He, CH4