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We've gotten adequately adept at spotting exoplanets out at that place in the vastness of infinite, but we still know very little about them. Astronomers can usually merely surmise most the surface conditions based on a planet'south size and proximity to its star, but NASA researchers are toying with the idea of looking for the glint of alien oceans every bit a way of detecting water.

We don't yet take the technology to report exoplanets directly, but that day is fast budgeted with the instruments similar the James Webb Infinite Telescope just a few years away. To ready for that 24-hour interval, astronomers are using the only habitable planet nosotros know of as a model — Earth. What would Globe look like if nosotros were studying it from a few lite years away?

We're used to seeing Earth from space as a brilliant blue marble in a sea of stars, simply that's simply what it looks like up shut. From a distance, World goes through phases like the moon does. During the crescent phases, the reflection of light from the oceans gets very bright — so vivid that the right instrument might be able to detect information technology from very far away.

earth_crescent_phase

An example of this was seen in 2009 when NASA's Lunar Crater Ascertainment and Sensing Satellite(LCROSS) spacecraft defenseless a glimpse of Earth and the moon from the night side of the moon (seen above). Scientists at NASA'south Ames Inquiry Center analyzed the data caused from LCROSS and institute that the ultraviolet and visible light signature provided a adept approximation of what Earth'southward surface looks similar with respect to land and h2o coverage. It was practiced enough to pick out details like the Pacific and Atlantic ocean, at least.

The LCROSS data showed that even when less of the Earth'due south surface is visible during the crescent phases, its effulgence could increase from forty-fourscore%. This kind of marked increase detected on an exoplanet would offer extremely strong evidence of liquid water on its surface. A planet with oceans should deport in more or less the same fashion as Earth when observed from a distance, but we besides have to effigy in things like its mass and location in the solar system. A planet might have a highly reflective surface, merely exist exterior of the habitable zone. That could indicate ice or some other liquid on the surface. Even excessive cloud encompass could cause an increase in reflectivity.

Any detection of the glint from a probable body of water would be a huge deal, even if it takes additional studies of the exoplanet'due south temper to confirm it. We've had such express information on the planets themselves that whatsoever hints could be revolutionary.