New Earth-sized planet found in habitable zone, boosts Earth 2.0 hunt

A potential Earth-like planet has been discovered in the habitable zone of a sun-like star, thanks to a breakthrough by Chinese and German scientists using a lesser-known detection method. 

The planet, named Kepler-725c, has about 10 times the mass of Earth and could support conditions suitable for life, according to a study published in Nature Astronomy on Tuesday.

Unlike previous detections that rely on visible planetary transits or radial velocity signals, the researchers employed the Transit Timing Variation (TTV) technique to infer the existence of the new planet. By analyzing timing irregularities in the orbit of a neighboring gas giant, Kepler-725b, the team deduced both the mass and orbital path of the hidden planet.

"It demonstrates the potential of the TTV technique to detect low-mass planets in habitable zones of sun-like stars," said Sun Leilei, lead author from the Yunnan Observatories of the Chinese Academy of Sciences.

Kepler-725c orbits its host star every 207.5 days – roughly two-thirds of an Earth year – placing it squarely in the star's habitable zone, where temperatures may allow liquid water to exist, a key ingredient for life.

Located about 2,472 light-years from Earth, the star system Kepler-725 is similar in temperature and luminosity to our sun, making it a strong candidate in the ongoing search for life beyond our solar system.

Research team leader Gu Shenghong, who's also from the Yunnan observatories, noted that although the planet meets key criteria for habitability, further investigation is needed to determine whether it can support Earth-like life.

The discovery was made by a team from the Yunnan Observatories, in collaboration with Xi'an Jiaotong-Liverpool University, the Nanjing Institute of Astronomical Optics and Technology, and Hamburg Observatory.

(With input from Xinhua)