Mars, Earth, Venus, Mercury. Solar system planets. Mars surface with craters. Planets line up or planetary opposition. Contains NASA image elements.

align, alignment, astronomy, astrophysics, atmosphere, background, celestial, cosmic, crater, deep, earth, exploration, galaxy, interplanetary, landscape, light, line up, mars, marscape, marsscape, martian, mercury, milky way, nature, nebula, nebulae, orbit, parade, planet, planetarium, planetary, planetary opposition, planets, retrograde, satellite, science, settlement, solar system, space, space background, space exploration, stars, sun, surface, syzygy, terrestrial planets, universe, venus, view, Science, Landscapes,