Exoplanet Guide

Scienceline’s Guide to the Exoplanets: The Question Mark

Wolf 1061c: a habitable planet very near Earth...maybe

April 28, 2020
A fake planet with "Scienceline's Guide to Exoplanets" labeled across its equator. Other planets zoom past behind it.
Your favorite planets, and you didn't even know they existed. [Credit: Curtis Segarra | CC BY-NC-ND 2.0]

The Question Mark
Wolf 1061c
Discovered by: University of New South Wales
Discovered: 2015
Distance from Earth: ~14 light-years
Size: ~1.6 Earth radii
Surface climate: Very hopefully a little chilly
Habitability for humans: Very possible

This time, we’re talking about yet another very close exoplanet — one of the closest planets we know that could be capable of supporting Earth-like life.

Wolf 1061 is a red dwarf, one of the nearest stars to the Sun. You can’t see it with your naked eye from Earth — even though it’s so close to Earth, it’s just too small and too dim. Wolf 1061 has three known planets so far, but Wolf 1061c, the middle of those worlds, has attracted by far the most attention.

Wolf 1061 is not too much larger than the Earth — and, more intriguingly, is comfortably within its star’s habitable zone. It’s probably not quite as warm as Earth, but astronomers believe it’s at least warmer than Mars.

At Wolf 1061’s size, its system’s habitable zone, where liquid water might exist, lies entirely within where the orbit of Mercury would be. The catch there is that planets who are that close to their stars tend to be tidally locked, and — although it isn’t known for sure — Wolf 1061 is, more likely than not, no exception.

We’ve talked about tidally locked planets on this blog before; one of their sides is eternally inward-facing, basking in its sun’s light and baking in heat, while the other faces a freezing night that will last forever. In between those two extremes, without any confounding outside factors, is a narrow band with a precariously pleasant climate.

If Wolf 1061c were like that, then it would seem that the planet becomes much less habitable.

But it’s not quite so simple as that, especially when it comes to larger planets.

For instance, what if Wolf 1061c has an atmosphere? The planet’s certainly large enough to keep one, even in the face of tidal locking; furthermore, if there’s anything resembling Earth life on its surface, it’s hard to imagine it surviving without an atmosphere. An atmosphere would, for instance, allow heat to transfer to the planet’s dark side — perhaps increasing the temperature and making more of its surface habitable.

Again, we don’t yet know if such things happen on Wolf 1061c. But its very close distance and its likeness to Earth make it a very promising place to look, even if we don’t find anything quite like Earth there — and it’s not even the nearest Earth-like planet.

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