Newly Found Planet Could Host Primitive Life, Study Suggest
It's an exciting find given the planet is only six light-years away from Earth, making it one of closest worlds outside of our solar system.
Primitive life might exist on a large, rocky planet that is relatively nearby Earth, according to a team of scientists who presented their work at an astronomy conference last week.
The team says that the planet – known as Barnard b or GJ 699 b – might have microbes or other simple life in its environment as long as there is a lot of thermal activity within the planet itself. This would theoretically provide enough energy for life to survive.
It's an exciting find given that the planet is only six light-years away from Earth, making it one of closest worlds outside of our solar system. There is another potentially habitable planet at Proxima Centauri roughly four light-years away from us, which is also coming under scrutiny. (A light-year is the distance light travels in year, or 5.88 trillion miles (9.5 trillion km).
The planet orbits Barnard's star, a red dwarf star that is slightly smaller and cooler than our sun. Like many stars of its type, Barnard's star puts out a lot of X-ray and ultraviolet radiation that could hurt any nascent life on the planet. However, the planet lies a little outside of the worst of the radiation, providing hope that life could indeed survive as long as it is hardy.
The planet is probably a super-Earth, roughly three times the mass of our own planet. Scientists suspect super-Earths like this one have a large, hot iron core with higher geothermal energy compared with Earth. This geothermal energy could heat the planet's environment using vents or plumes, similar to what happens in ocean environments on Earth – even in cold areas like Antarctica.
In their presentation, the researchers jokingly compared the planet to Hoth – the icy planet made famous in one of the "Star Wars" movies, when Luke Skywalker's steed (a fictional lizard species called a Tauntaun) dies and he must stay warm by burrowing into its intestines.
But the challenge for the team is proving life may exist on the newly discovered planet, which was first announced in November in a Nature publication. There's no telescope powerful enough yet to look at the planet's atmosphere for biologically friendly molecules, such as oxygen or methane. That would require – at the least – the launch of NASA's James Webb Space Telescope, which is set to go to space no earlier than 2021. Or it may require an even more powerful telescope in the future.
"Directly imaging the planet would be able to tell us its precise brightness, and we could gather more information about temperature and properties such as albedo [reflectivity]," said Villanova Unviersity astrophysicist Scott Engle to Seeker; he participated in the research along with fellow Villanova astrophysicist Edward Guinan. Guinan provided a copy of their presentation to Seeker.
Albedo is helpful in part because it can tell astronomers if the surface is made of highly reflective materials, such as ice, or less reflective materials, such as rock. Since life as we know it prefers water, a planet with water or water ice on its surface would have a stronger argument for habitability.
The study of life on other worlds is still in its infancy and few spacecraft have looked for life directly. NASA is working on a mission called Europa Clipper that could look for habitable conditions at Jupiter's icy moon, Europa. Europa has a liquid ocean under its ice because the tidal energy from strong Jupiter keeps the ocean from freezing over.
"Getting more data on Europa would be very impactful," Engle said. "Currently we are left with theories and a few Earth-based examples of subsurface oceans such as Lake Vostok in Antarctica. Studies at icy moons, the Holy Grail of which would be something like the Europa Clipper, would finally advance us beyond the boundaries of terrestrial examples like Lake Vostok ... which would be huge."
While the astronomers wait for these datasets to become available, they still have other ways of gathering information; they will examine the star's wobble to see if they can learn any more properties about the planet, and to search for any planetary companions. The team will monitor the variations in the star's light to pin down the star's rotation, and also to look for sunspots – just like on the sun.
They also are looking at alternative techniques to take images of the planet. They have a couple of early ideas already. Perhaps they will use a set of telescopes on the Earth working together as an interferometer, or use extremely sensitive adaptive optics that could help the telescope deform its mirror to counteract atmospheric turbulence that blurs out the sky.
The researchers presented their work at a Jan. 10 press conference held at the 233rd meeting of the American Astronomical Society in Seattle.