Hubble celebrates Neptune's first birthday

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July 12 2011 12:15 PM

Hubble celebrates Neptune's first birthday

Just a quick update to my post about Neptune's birthday: the folks at Hubble just released some nifty images of the big blue planet taken just a few weeks ago!

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death from the Skies! Follow him on Twitter.

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These four images show Neptune using blue, red, and near-infrared filters. The atmosphere of the planet is laced with methane, which strongly absorbs red light and makes Neptune appear very blue to the eye. I've seen it through a telescope and the color is striking; I was using a 25 cm telescope at the time and the planet was just barely resolved as a disk. At 4.5 billion kilometers (3 billion miles) away, it's amazing even that was discernible!

In the big Hubble image above, the pink color is infrared light reflected from high-altitude clouds, and each image was taken four hours apart. In the smaller picture here (click to embiggen it), several of Neptune's moons can be seen, showing up as a series of dots as they moved between exposures. At the moment, 13 moons orbiting Neptune are known, ranging from the 2700-km-wide (1600 mile) Triton down to some smallish guys only 40 or so km across. There are undoubtedly more, but the planet is a long way off, and anything smaller than that is really hard to see.

We've learned a huge amount about Neptune -- all the planets, of course! -- since it was discovered in 1846. With bigger telescopes, better detectors, and the ability to leave the bonds of Earth and loft telescopes above the atmosphere -- and even carry them on probes that go to the planets themselves, like Voyager 2 did when it flew past Neptune in 1989 -- our curiosity has only increased. And to think, we've only been studying Neptune for one year...

Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)