... Tempel Tuttle: The Leonid Comet . ... Mercury And The Moon . ... Mercury is the closest planet to the Sun and never moves far from our parent star in Earth's sky. ... Until then, spiral galaxies NGC 2207 and IC 2163 will slowly pull each other apart, creating tides of matter, sheets of shocked gas, lanes of dark dust, bursts of star formation, and streams of cast-away stars. ... As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly...