If you’re looking for an Earth-like planet with an atmosphere, you need only go outside. Alternatively, you could travel some 39 light-years toward the constellation Vela. That’s where astronomers have discovered an exoplanet called GJ 1132b, which appears to have an atmosphere. While it might not be particularly hospitable to human life, some other organism might find it quite cozy.
GJ 1132b was first detected in 2015, but we didn’t know about its atmosphere. Astronomers at the time reported the planet was Earth-like, at least in a broad sense. It’s about the same size, and has a similar mass. However, it’s orbiting close to a red dwarf star—a year for GJ 1132b is only 1.6 Earth days. That means it’s probably exposed to a great deal of radiation, and the surface temperature is believed to be around 700 degrees Fahrenheit (371 degrees Celsius). The planet is also tidally locked to the star, meaning it does not rotate. So, one side is roasted and the other frigid.
Detection of GJ 1132b was accomplished with the transit method, which watches for dips in light as a planet passes between its star and Earth. The new analysis of GJ 1132b was led by John Southworth, an astrophysicist at Keele University in the UK. After the initial discovery, Southworth began working on a modification of the transit observation that could detect an envelope of gas around the exoplanet. The team found a measurable dip in “z-band” light during GJ 1132b transits. This absorption of this near-infrared wavelength of light indicates that GJ 1132b most likely has an atmosphere.
Comparison of Earth and GJ-1132b.
The existence of an atmosphere around GJ 1132b isn’t all good news for habitability. There’s likely a greenhouse effect of some sort, which would push the temperature even higher. It’s safe to say that even the advent of interstellar travel would not make GJ 1132b a suitable vacation spot. However, this could have huge implications for habitability elsewhere in the universe. Red dwarfs are the most common type of star in the observable universe. If this exoplanet orbiting a red dwarf has an atmosphere, many others do too. Maybe some of them are more pleasant and legitimately Earth-like than GJ 1132b.
Simply being able to confirm an atmosphere around an exoplanet is a big step forward in the search for extraterrestrial life. The existence of life on a planet will likely have an effect on the atmosphere, which is something we may be able to detect. Our method would need to be much more sensitive first. It’s possible the James Webb Space Telescope will be able to gather data on the composition of exoplanet atmospheres when it launches in a few years.
