Since Pluto's demotion from the brotherhood of planets a few years back, Neptune has taken on the mantle of responsibility of most distant planet in the solar system. It's big, about 4 times the diameter of Earth, but so far away - 4.4 billion kilometers (2.7 billion miles) away at its closest - that even in big telescopes it's hard to see detail. Astronomer Mike Brown used one of the biggest telescopes on Earth, the monster 10-meter Keck eye in Hawaii, to observe Neptune in September 2011, getting this lovely infrared picture of it. The bright bands around Neptune are high-altitude clouds, similar to the cloud patterns we see on Jupiter and Saturn.
And oh, did I say he was observing Neptune? Actually, Mike studies the giant frozen iceballs that orbit the Sun out past Neptune, so really he was more interested in Neptune's moon Triton, seen to the lower right in that picture. Triton is so similar to those other objects that it may actually have once been one, captured eons ago by Neptune's gravity. It's unclear how something like that could've happened, so observations of these distant denizens of the outer solar system are important for us to understand the history and evolution of our local neighborhood.
Image credit: Mike Brown
Original blog post