Scientists search for signs of life on nearby exoplanet

Los Angeles: In an attempt to search for life beyond Earth, astronomers have found that a planet about 14 light years away is located within the habitable zone - the region where liquid water could exist on its surface. The question of whether Earthlings are alone in the universe has puzzled everyone from biologists and physicists to philosophers and filmmakers. Stephen Kane, astronomer at San Francisco State University in the US focused on finding "habitable zones," areas where water could exist in a liquid state on a planet's surface if there is sufficient atmospheric pressure.

Kane and his team examined the habitable zone on a planetary system 14 light years away. "The Wolf 1061 system is important because it is so close and that gives other opportunities to do follow-up studies to see if it does indeed have life," Kane said. However, it is not just Wolf 1061's proximity to Earth that made it an attractive subject for Kane and his team.

One of the three known planets in the system, a rocky planet called Wolf 1061c, is entirely within the habitable zone, researchers said. Researchers were able to measure the star around which the planet orbits to gain a clearer picture of whether life could exist there. When scientists search for planets that could sustain life, they are basically looking for a planet with nearly identical properties to Earth, Kane said.

Like Earth, the planet would have to exist in a sweet spot often referred to as the "Goldilocks zone" where conditions are just right for life. The planet can not be too close or too far from its parent star. A planet that is too close would be too hot. If it is too far, it may be too cold and any water would freeze, which is what happens on Mars, Kane added. Conversely, when planets warm, a "runaway greenhouse effect" can occur where heat gets trapped in the atmosphere.

Scientists believe this is what happened on Earth's twin, Venus. They believe Venus once had oceans, but because of its proximity to the Sun the planet became so hot that all the water evaporated, according to NASA. Since water vapour is extremely effective in trapping in heat, it made the surface of the planet even hotter. The surface temperature on Venus now reaches around 471 degrees Celsius. Since Wolf 1061c is close to the inner edge of the habitable zone, meaning closer to the star, it could be that the planet has an atmosphere that is more similar to Venus.

"It is close enough to the star where it is looking suspiciously like a runaway greenhouse," said Kane. Kane and his team also observed that unlike Earth, which experiences climatic changes such as an ice age because of slow variations in its orbit around the Sun, Wolf 1061c's orbit changes at a much faster rate, which could mean the climate there could be quite chaotic. The study appears in the Astrophysical Journal.