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The planets beyond Saturn are far away, and astronomers need big telescopes to see them.
Uranus was discovered in 1781, and Neptune in 1846. Pluto was not spotted until 1930. All three planets are cold because they’re so far from the Sun. Uranus is twice as far from the Sun as Saturn is, which puts it about 2 billion miles out. Neptune is 2.8 billion miles from the Sun. Pluto is 3.5 billion miles from the Sun.
Uranus and Neptune are giant balls of water covered by thick hydrogen atmospheres. Another gas, methane, soaks up atmospheric red light from the Sun. But it reflects blue and green light back into space. Methane makes both Uranus and Neptune look blue-green in color. On Earth, bacteria can make methane. Moons and dark rings of dust orbit both planets.
