The search for extraterrestrial life continues with the discovery of more near-twin planets outside of our solar system.

Astronomers announced on Tuesday that they have confirmed the existence  of three or four Earth-like planets, depending on the definitions used. These planets are roughly the same size as Earth and located in the ‘Goldilocks Zone’, or the area in which planets could harbor liquid water and theoretically support life. This brings the total number of Earth-like planets discovered by NASA’s Kepler telescope to eight.

These planets are most likely to be terrestrial, not gas giants or ice worlds. They are receiving roughly the same levels of energy from their stars as Earth gets from the sun, according to the latest figures from the Kepler telescope.

However, these planets are only close in size and temperature to Earth in the grand scale of the universe.

Take, for example, the two planets discovered to be nearest to Earth. If we assume that their atmospheres are comparable to Earths, the odds of which are low, then the surface temperature of one would hover around 140 degrees while the other would be about zero, said Guillermo Torres, lead author of the study and astronomer at the Harvard-Smithsonian Center for Astrophysics.

Regardless, the findings are another step toward answering the question of life in the universe.

“These planets do exist. We didn’t know that before,” said Torres in an interview with Fox. “What we’re really looking for is signs of life eventually. We’re not there yet. It will take many years, but this is the first step.”

The study highlighted two of the new planets that were closest in size to Earth. Kepler-438b is the closest in size, with a diameter only twelve percent larger than Earth’s. The planet gets about 40 percent more energy from the red dwarf star it orbits than Earth gets from the sun. For reference, the study points out that Venus receives 100 percent more energy.

Kepler-438b orbits much closer to its star, with a year lasting only 35 days. The close proximity to its star would be responsible for the higher surface temperatures.

“There are bacteria on Earth that live very comfortably in those temperatures, no problem,” said Torres.

The other planet, Kepler-442b, is about 33 percent larger than Earth. However, the planet receives only two-thirds of the solar energy we gt from the sun. The team has determined that Kepler-442b has a 97 percent chance of falling into the habitable zone of its star.

“We don’t know for sure whether any of the planets in our sample are truly habitable. All we can say is that they’re promising candidates,” said second author of the studyDavid Kipping in a statement.

As with most exoplanets, the distance from Earth will make further study and observations a difficult task. Kepler-438b is located 470 light-years from Earth and Kepler-442b is located 1,100 light-years away. A light-year is the equivalent of 5.9 trillion miles.

The original study has been accepted for publication by The Astrophysical Journal.