Global campaigns observe Venus again

Phobos's appearance completed the discovery of the planet's two familiar moons.

The newly discovered moon orbits nearer to Mars than Deimos.

With both moons identified, astronomers could study their motions around Mars.

The 6 December transit was the second in the 1874–1882 pair.

NASA reproduces a photograph of Venus crossing the Sun made by students at Vassar College.

Photographs preserved a measurable visual record of a rare celestial alignment.

Edward Emerson Barnard found a fifth moon of Jupiter.

Amalthea was much fainter than the four large moons seen by Galileo.

Barnard's observation was the last major satellite discovery made visually rather than from photographs.

The new moon orbits closer to Jupiter than the four Galilean moons.