First planets seen with visible light!
News came out today:link-icon: about no less than three planets:link-icon: which the Hubble Telescope has photographed in the visual light spectrum. In other words, these are the first planets to be photographed “as the human eye” would see them. Of course, they still look like tiny dots, given that they are trillions of kilometers away from here. But still…it’s a landmark observation. And the picture of one such planet, Fomalhaut b, is pretty spectacular in its own way:
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As noted previously, the planet itself is just one dot among many, a slightly brighter point of light amidst the glow reflected from what I think is a dust cloud. But notice too the evidence of banding in the cloud, suggesting that the planet’s substantial gravity (we’re talking about a Jupiter-sized world here) is pulling more and more of the dust close to its orbit.
The other two planets are in orbit around the star HR 8799.
One thing that makes these particular planets a bit easier to find than usual is that they are young; HR 8799 and its children are only about 60 million years old. That means the planets are still glowing from the leftover heat of their formation, and that adds to their brightness. Eventually (in millions of years), as they cool, they will glow only by reflected light from the star, and be far harder to see. Fomalhaut b, in the Hubble image, is much older (200 million years), and glows only by reflected light from Fomalhaut. If it were much smaller or dimmer (or closer to the blinding light of the star), we wouldn’t have been able to see it at all.
The most advantageous aspect of these discoveries is that because the planets are fairly young, in comparison to our own, they give us a glimpse (albeit at substantial distance) of what a planetary system looks like in its (relative) youth, which in turn could teach us much about the natural processes that shaped our own solar system.
