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The planets past Saturn are far away.
Astronomers need big telescopes to see them. Uranus was discovered in 1781, and Neptune in 1846. Astronomers didn’t find Pluto 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, or about 2 billion miles. 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. Both are surrounded by thick hydrogen atmospheres. Methane, another gas, soaks up red light from the Sun in the atmosphere. Yet it reflects blue and green light back into space. The gas makes the two planets look blue-green. On Earth, some bacteria make methane. Moons and dark dust rings orbit both planets.
