... Mercury on the Horizon . ... Because Mercury orbits so close to the Sun, it never wanders far from the Sun in Earth's sky. If trailing the Sun, Mercury will be visible low on the horizon for only a short while after sunset. ... Hard to spot against the twilight glow near planet Earth's horizon, a crescent Mercury was imaged close up by the MESSENGER spacecraft early last week. ... Winter Night at Pic du Midi . ... Andromeda Island Universe . ... Orbiting Astronaut Reflects Earth . ...