A Cold Earth 146 Lightyears Away Could Be Habitable

Astronomers have found evidence of a potentially habitable planet and have named the space rock “HD 137010 b.” It has been described in The Astrophysical Journal Letters.

While it is still technically listed as a “candidate” planet, the discovery is particularly intriguing because its positioning means it may be the first Earth-like exoplanet that is both near enough and bright enough for astronomers to follow up in future observations.

“This is a significant addition to the small sample of cool Earth-sized exoplanets, and presents a small milestone in the search for Earth-like exoplanets around nearby sun-like stars,” the researchers wrote in the study.

Read More: Weird Lemon-Shaped Exoplanet Discovered Orbiting a Bizarre Star

What Do We Know About Hd 137010 B?

HD 137010 b may be 146 light-years from Earth, but it appears to share some uncanny similarities with our own planet. At an estimated 355 days, its orbital period — the number of times it takes to complete a round trip of its star — is roughly a year. Meanwhile, its radius is only fractionally bigger. According to the researchers’ calculations, it’s equivalent to approximately 1.06 Earths.

There is a catch: it may not be all that hospitable. That is because this particular exoplanet teeters on the very edge of its planetary system’s habitable zone, receiving less than a third of the light Earth obtains from the sun.

The fact that HD 137010 b’s star (an orange dwarf) is colder and dimmer than our own (a yellow dwarf) means its surface may reach a top temperature of minus 90 degrees Fahrenheit (minus 68 degrees Celsius). That is colder than average temperatures in Antarctica’s interior and on Mars, where the average surface temperature is a cool minus 85 degrees Fahrenheit (68 degrees Celsius), according to the Australian Antarctic Program.

This does not rule out habitability entirely. Much depends on the composition of its atmosphere. One moderately rich in carbon dioxide could result in the formation of liquid water, whereas an atmosphere naturally low in carbon dioxide, such as Earth’s, “might instead result in a frozen 'snowball' climate,” the authors wrote in the study.

In all, the researchers believe there is a 40 percent chance it falls inside a more conservative habitable zone, a 51 percent chance it falls within an optimistic habitable zone, and approximately 50 percent chance it falls outside the habitable zone altogether.

What Makes A Planet Habitable?

A planet may be habitable if it exists in the Goldilocks zone. This means it is neither too cold nor too hot, and it can hold liquid water on its surface. It also helps to be terrestrial, like Earth, rather than gaseous, like Saturn or Jupiter.

Another factor may be the host star itself. K-dwarf stars (or orange dwarf stars) like those in HD 137010’s planetary system are thought by many to be more suited to life than the G-type (or yellow dwarf stars) in our own. According to NASA, their longer lifespans offer greater timescales for life to form. Plus, there are simply more of them in our galaxy to start with.

As for how many habitable planets exist, a study in The Astronomical Journal found there could be as many as 300 million in the Milky Way.

What Happens Next for HD 137010 b?

For now, HD 137010 b is categorized as a “candidate” planet. This is because the evidence so far is based on a singular 10-hour transit captured during Kepler’s second mission. It was detected as it passed over the surface of its host star and caused the starlight to dim. Additional observations must take place for its status as a true exoplanet to be confirmed.

“To our knowledge, this is the smallest planet candidate detected from a single transit around a sun-like star,” the study’s authors wrote. It may also be “among the coolest Earth-sized transiting planets yet discovered orbiting a sun-like star.”

Read More: Kepler 452b and Several Exoplanets Are Similar to Earth, but There's Not an Exact Twin

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• This article references information from a recent study published in The Astrophysical Journal Letters: A Cool Earth-sized Planet Candidate Transiting a Tenth Magnitude K-dwarf From K2
• This article references information from NASA: Discovery Alert: An Ice-Cold Earth?
• NASA: About Half of Sun-Like Stars Could Host Rocky, Potentially Habitable Planets
• This article references information from a study published in The Astronomical Journal: The Occurrence of Rocky Habitable Zone Planets Around Solar-Like Stars from Kepler Data
• Australian Antarctic Program: Antarctic weather