2. Neptune
Neptune is known as one of two “ice planets” and is about 17 times as massive as Earth.
First viewed through a telescope in 1846, Neptune was initially called “the planet exterior to Uranus.”
Neptune’s atmosphere has active and visible weather patterns, complete with incredibly strong winds that can reach the speed of sound at times. The planet’s storms can be seen as white streaks in the photo below.
Neptune has 14 known satellites, which are named after Greek and Roman deities of the sea. The planet has only been viewed up close one time, by the Voyager 2 spaceprobe in 1989.
source: NASA
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