Challenge of the Stars

Algol Amalthea Apollo asteroids astronauts astronomers atmo atmosphere base Beta Lyræ brilliant carbon dioxide century close clouds cluster comet craters dark degrees Fahrenheit Deimos dense diagram diameter disk distance Earth Earth-days eclipsing binary edge-on escape velocity extremely faint fainter Galaxy Grand Tour gravity hydrogen hypothetical planet Icarus inner satellites interstellar Jupiter known land lapetus launched less light light-years luminosity luminous lunar Main Sequence Mariner 9 Mars Martian material Mercury miles per second million module Moon moving round naked eye Nebula Neptune nova Observatory observer orbit painting perihelion Phobos photographs picture planet moving planetary system Pluto polar possible probe Proxima Proxima Centauri radiation radio telescopes reach red giant revolution period Rhea rings rocket rocks rotation Saturn scene seen shown shuttle Sirius Skylab Solar System space space-station spiral star station surface temperature Titan Trifid Triton Uranus vehicles Venus visible white dwarf Zeta Auriga Zeta Cancri