“an unprecedented achievement from an Earth-based observatory”

Nasa are celebrating the apparently successful demonstration of a new technique used, with Nasa’s relatively modest 30-year-old, 3-meter-diameter, Infrared Telescope Facility in Hawaii, to identify water, carbon dioxide and methane in the atmosphere of exo-planet HD 189733b – a Jupiter-size planet nearly 63 light-years away. Here’s a NASA/JPL-Caltech graphical explanation. And the BBC report. Nature has the technical details. Somewhere, the “Ingenious Mr [Robert] Hooke” is smiling. As he said in the preface to his 1665 publication Micrographia

‘Tis not unlikely, but that there may be yet invented several other helps for the eye, as much exceeding those already found, as those do the bare eye, such as we may perhaps be able to discover living Creatures in the Moon, or other Planets, the figures of the compounding Particles of matter, and the particular Schematisms and Textures of Bodies.

As the BBC report notes

“It’s a pretty interesting discovery,” said Keith Horne, an astrophysicist and exoplanet expert from the University of St Andrews.

“The main impact is this strong emission line that stands out quite dramatically,” he told BBC News.

“You’d be able to detect it on other objects that are farther away [from their parent stars] or are fainter. So far, it’s been just the nearest, transiting ‘hot Jupiters’ that are bright enough to detect this secondary eclipse.”

But more than that, the new research shows that some observations that were once only possible from space can now be done using ground-based telescopes.

That vastly increases the number of instruments – far larger than the 3m telescope used in the Nature work – that could be trained on exoplanet atmospheres.

“Larger telescopes could look at this in more detail, because there’s so many of them. It potentially allows many different teams to participate; previous detections with the Hubble and Spitzer telescopes are great, but there’s only one Hubble and only one Spitzer.”