Earth’s Twin Update: Reflection of Alien Oceans Could Reveal Habitable Planet

6a00d8341bf7f753ef0133f426d139970b.jpg The next generation of telescopes could reveal the reflection of light or "glint" from Ocean surfaces that signal the existence of Earth-like planets outside our Solar System. Scientists hope the reflection of light from mirror-like ocean surfaces could be picked up by the James Webb Space Telescope, Hubble's successor, set for launch in 2014. Tyler Robinson at the University of Washington in Seattle is hoping this new technique could be used in the quest to find the Holy Grail for exoplanet astronomers – a possible twin Earth.

 "We're focussing on a class of extra-solar planets yet to be detected, so things comparable in size and composition to the Earth and similar distances from their central star as the Earth is from the Sun," Robinson told BBC News. "The goal is to find something Earth-like in almost every sense of the world so we can even prove it has liquid oceans on its surface."


This kind of ocean could be the signature of a planet where life had developed in the same way as it did on our own planet.

"The glint I'm talking about is pretty much the exact same thing when you talk about gorgeous sunsets over the ocean. With the sun low on horizon, sun beams come in and glance off the ocean surface which is acting like a mirror and you get these beautiful red sunsets."

Glint detected on Saturn's moon Titan confirmed the presence of a methane ocean. Tthese tell-tale glint spots are vital to finding Earth-like planets because, at distances of 20 or 30 light-years away, astronomers are decades from being able to image the surface of these alien worlds.

"You would need to have a telescope that is absolutely humongous to make these kinds of measurements. It would have to be on the scale of the distance between Earth and Mars," Mr Robinson told BBC News

Tyler Robinson hopes the James Webb Space Telescope could be used to help observe glint from exoplanets when it is launched in 2014. The JWST has been dubbed by some as the successor to Hubble and its job will be to peer into the early Universe and look for the formation of the first galaxies.

But the telescope would need a bit of extra help, he told BBC News."That on its own isn't quite capable of making these measurements. What we would need is an external occulter," Mr Robinson explained."This is a separate shield that you would launch into space that has the job of blocking the light from a star and by blocking that light it enables you to see the dim little planets that are orbiting around that star. "

As well as liquid water, another way life could be detected on exoplanets is through the presence of vegetation. Chlorophyll, the green pigment in plant leaves, is very strongly reflective at near infrared wavelengths. This bright red appearance of vegetation at such wavelengths is known as the "red edge".

Jason McManus via BBC News

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