September 26, 2013
The Hunt For Extraterrestrial Life On Cloudy Extra-Solar Planets
Brett Smith for redOrbit.com - Your Universe Online
An international research team has created a map of the clouds that ensconce Kepler 7b, a distant planet outside our solar system, according to reports published by The Astrophysical Journal and Astrophysical Journal Letters.
The studies’ researchers said their findings are a step forward in determining which planets outside our Solar System, also known as exoplanets, can host extraterrestrial life.
A property of this exoplanet that makes it particularly interesting for researchers is the reflective quality of its atmosphere. The planet’s atmosphere reflects around 50 percent the light, which is considered to be highly reflective.
The reason for this strong reflective quality, the team was able to demonstrate, is because it is surrounded by a layer of highly reflective clouds. Through observations of different phases of Kepler 7b as it orbited its star, similar to the different lunar phases, the research team was able to measure these clouds for the first time.
From these measurements, the research team was able to build a "phase curve," which was then transformed into a crude east-west map of the planet. The unexpected composition of the map, combined with the high reflectivity of the atmosphere, implied the existence of clouds, the researchers concluded. The map structure also revealed information on the size of the cloud particles.
The team suggested that their work is an important step in learning about the influence of clouds on the atmospheres of exoplanets, adding that this knowledge is a prerequisite in the search for extraterrestrial life.
Clouds on exoplanets were once an obstacle in the search for habitable planets, but these new studies are the first to investigate clouds on planets outside our Solar System.
"Clouds are a nuisance, because they hinder us from performing a unique interpretation of an exoplanet atmosphere," explained study author Kevin Heng, an astronomer from Center for Space and Habitability (CSH) at the University of Bern in Germany.
There may be hundreds of ways of interpreting the chemical makeup of a planet’s atmosphere when it is covered in a layer of clouds. This problem is especially significant in the search for life outside our Solar System, which begins with the characterization of the atmospheres of exoplanets.
"The fear is that clouds will confuse our ability to clearly identify the signatures of life from scrutinizing the spectrum of an exoplanetary atmosphere, which is why we are investing time and energy to understand the effects of clouds," Heng said.
Kepler 7b was one of the first five exoplanets to be confirmed by NASA’s Kepler space observatory, a massive telescope that trails the Earth in its orbit around the sun. Referred to as a “hot Jupiter,” Kepler 7b is slightly bigger than our Solar System’s largest planet, but it is thought to contain half the mass. It orbits its star, Kepler 7, every five days at about the same distance as Venus is from our own sun.