Friday, 12 July 2013

Got the exoplanetary blues

That image
There has been a lot of news coverage in the last day or two of the discovery of a blue exoplanet - a planet orbiting another star. It is quite a feat to detect colour at this distance, but I feel that the news coverage is tainted by a combination of misapprehension and downright naughtiness.

To begin with, why should we care that the planet is blue (and hence splash it across the media)? After all, it has to be some colour. So what if it's blue? The only reason I can think for getting excited is that traditionally this colour has been associated with life. We know that Earth is primarily blue when seen from space because of its oceans and so link this with a friendly environment. What this misses is that Earth isn't the only planet in the solar system that is blue. Both Uranus and Neptune are blue too.

This blue coloration is not because these gas giants distant from the Sun are ideal for life. Quite the reverse. It is because that's the right sort of colour for a methane atmosphere. So we shouldn't get too excited, given two out of the three blue planets we know well aren't anywhere near inhabitable. In fact, to give the news media their due, they have all reported that HD 189733b, located around 63 light years away, is probably blue because of liquid or fragmentary silica in the atmosphere. And most have pointed out that it is a gas giant. But given that, it's not quite clear why they have got so excited about it. There is something worse, though.

Pretty well every bit of coverage I've seen has carried this stunning image from NASA/ESA. And why wouldn't they? It puts some of the pictures of planets in our own system to shame, let alone a planet 63 light years away. Of course, the reason it is so good is that it is an artist's impression. It's not a photograph. The colour detection has been through changes in the colour spectrum when the planet passes behind its star, not through direct observation, and certainly not through stunning photographs. And yet almost all the coverage I've seen has not mentioned that this picture is a fake.

Take, for instance, the write-up in the usually excellent i newspaper. They have given it a quarter page. Of that, maybe two thirds is the picture and the rest is a small text box. The closest it comes to saying the image isn't genuine is saying the planet is 'a deep cobalt blue, data gathered by the Hubble space telescope shows.' I'm sorry, I can guarantee you that a fair percentage of even the excellently educated readers of the i will come away convinced that they have seen a picture of this planet. It wouldn't be hard to put in an 'artist's impression' caption.

If you think I am being over concerned, it is because I think this demonstrates a widespread attitude in the media that you can loose and free with science reporting. Just imagine this was a story about a celebrity committing an offence and the paper mocked up a 'photograph' of it happening without labelling it as an artist's impression. It would cause on uproar. Just because this is science doesn't mean that such deception is acceptable.

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