GJ 1002 b and c lie at a perfect distance from their star which could allow liquid water to form on a planet’s surface.

With astronomy reaching the far end of the universe and trying to look at the moments just after the big bang, the catalogue of worlds beyond our solar system is continuously growing. Astronomers have now found two planets that are as massive as Earth and could be habitable.

GJ 1002 b and c lie at a perfect distance from their star, which could allow liquid water to form on a planet’s surface if it has the right kind of atmosphere. This zone known as the habitable zone, just like Earth is in from the Sun, has made astronomers more excited about this new discovery.

Planet b, which has a mass slightly higher than Earth’s, is the closer of the two and its year lasts only 10 days. Meanwhile, planet c is about a third more massive than Earth and takes about 20 days to orbit the star.

Astronomers said that the star dubbed GJ 1002 seems to be mature enough to have gotten over its youthful tantrums and now appears quiet. “It’s even possible that the early flaring helped build up a variety of molecules on the planets’ surfaces that could be used later, during the star’s quiet period, by any developing life forms that might be present,” researchers said in a statement.

The details of the findings have been accepted for publication in the journal, Astronomy & Astrophysics under the title “Two temperate Earth-mass planets orbiting the nearby star GJ 1002.”

Led by Alejandro Suárez Mascareno of the University of La Laguna, Spain, the team of researchers discovered the two new planets using radial velocity measurements. This method involves detecting the “wobbles” of the parent star caused by gravitational tugs from orbiting planets.

As the planets move toward the far side of the star, they pull the star away from us, causing the star’s light to shift toward the red end of the spectrum. As the planets move toward the star’s near side, they pull the star in our direction, shifting its light toward the blue. “The planetary tugs on GJ 1002 are tiny, about 4.3 feet per second – equivalent to moving at about 4.8 kilometers per hour. Such small movements are difficult to detect,” the team said.

The team relied on spectrographs to measure variations in light and follow-up observations revealed two Eart-like planets hanging around.

The two new planets join an elite category of planets that are small worlds in the “conservative” habitable zone that are less than 1.5 times the size of Earth or less than five times as massive. However, to fully establish that they are habitable, astronomers need to find out if these planets have an atmosphere or not.