Proxima b, The Closest Exoplanet We Know, May Be Even More Earth-Like Than We Thought

Not too long ago, the idea of habitable planets beyond our solar system was reserved for science fiction, but now, it’s not such a far-fetched notion.

With each passing year, scientists are discovering more and more potentially habitable planets.

One of the most promising specimens at the minute is an exoplanet known as Proxima Centauri b, or, if you’re looking to save a little breath, simply Proxima b. We now think it might be more Earth-like than we first assumed.

What Is An Exoplanet?

First discovered by the European Southern Observatory back in 1995, Proxima Centauri b has been studied extensively since then. But what exactly is an exoplanet? Well, let’s start with the basics.

An exoplanet is any celestial body orbiting another star other than the Sun. In this case, the star is Proxima Centauri, and the planet is Proxima b. In other words, an exoplanet is a planet that exists outside of our own solar system.

Where Is Proxima b?

To put things into perspective, here’s where Proxima b sits on the cosmic scale:

The planet orbits Proxima Centauri, a red dwarf star that lies about 4.2 light years from Earth, which is a mighty long way away, but Proxima b is also one of the closest exoplanets to us — about four trillion miles away — which means we may be able to study its atmosphere.

Proxima Centauri is the closest star to our sun and is one third of the triple star system labeled Alpha Centauri. Proxima b orbits its red dwarf star on an 11.2 Earth day system.

Proxima b occupies something known as a habitable zone, but what exactly does this mean? Let’s find out!

What Is A Habitable Zone?

A habitable zone is the area around a star where liquid water could exist on a planetary surface.

A habitable zone may also be referred to as a “Goldilocks zone”, as it’s not too close to a star, nor is too far away to completely rule out the idea that life could exist on a planet within it.

In general, the closer a planet gets to its host star, the hotter it will become, and after a certain point, there is simply no chance of water existing on the planet’s surface, and with no water, there can be no life.

But that’s not to say that all planets that are situated in a habitable zone are host to luscious mountain springs, oceans, and tons of life forms.

For any form of water to be present on the planet, we must also consider the atmosphere of the planet, as even Earth would be completely void of water and life without its atmosphere.

Now, considering that Proxima b is 20 times nearer to its star than Earth is to the sun, it would need some pretty significant atmospheric muscle to fend off damaging radiation.

In the absence of a suitable atmosphere to block harmful radiation from a star, all of it would pass straight on towards the planet, frying anything on its surface.

So, as you can see, a planet existing in a habitable zone doesn’t mean it can 100% harbor water and life, it just means there’s a small chance that it could or could have at some point in time.

Why Is Proxima b Getting A Lot Of Attention From Us?

We’ve known for a while that Proxima b exists inside the habitable zone around the red dwarf star Proxima Centauri, but the thing that’s really piqued our interest here is just how similar to Earth it appears to be in this early stage of our studying the planet.

The thing that’s got everybody excited is the size of the planet. It’s actually, relatively speaking, kind of Earth-sized.

According to NASA, Proxima b has a diameter of approximately 1.3 times that of Earth. This makes it the smallest exoplanet discovered so far, and, as we’ve already discussed, it’s also the closest exoplanet to us, which is pretty amazing.

Although the mass of the planet doesn’t have any direct implications regarding its ability to harbor life, it does give scientists hope that it’s a terrestrial planet, like Earth, thereby increasing the chances that it is potentially habitable.

Combine this with its location dead center in its star’s habitable zone, and it may well have water either on the surface or hidden away somewhere beneath the surface, and where there’s water, there’s a chance that there could also be life!

This is all very promising, but there are also a few things to consider that aren’t quite as hopeful.

Does Proxima b Have An Atmosphere?

The honest answer here is that, as it stands, we just don’t know if Proxima b has an atmosphere, let alone one robust enough to shield it from the right amount of Proxima Centauri’s harmful radiation.

Due to its proximity to Proxima Centauri, scientists are worried that the exoplanet does not have a strong enough atmosphere to harbor water.

But that’s not to say it absolutely doesn’t, because even though Proxima b is much closer to its star than we are to the sun, its star isn’t that large or powerful.

The mass of Proxima Centauri is only about 12.5% of the sun’s mass, so it’s not just a bit smaller, it’s incredibly small in comparison to the sun, which means Proxima b may have a fighting chance of developing the prerequisites of life.

Sadly, though, there’s something else that may be a problem for this exoplanet’s bid for life… its orbital path.

Does Proxima b Orbit Proxima Centauri Like Earth Orbits The Sun?

The course Proxima b charts around its red dwarf star is in no way similar to that of planet Earth’s route around the sun.

It’s thought that Proxima b is in what’s known as a tidally locked state, which essentially means the gravity of Proxima Centauri has forced it to orbit and rotate in a certain way.

Tidally locked celestials will always only show one side of their surface to the nucleus of their orbital system.

Our moon is the perfect example of this. It rotates on its axis, and it orbits the Earth, but we only ever see one side of it. For a moon, this is absolutely fine, but for a planet that’s supposed to harbor life, this is a little problematic.

Being tidally locked to a star means that only one side of the planet is ever going to receive light from the sun. Consequently, it will have one really hot side and one ridiculously cold side. Life doesn’t do well in the face of such extremes.

Final Thoughts

So, there you have it, Proxima b may well be Earth-like in terms of mass, but unfortunately, that doesn’t guarantee habitability. That’s not getting the scientists of Earth down, though.

There are plans in the works to study Proxima b in greater detail as well as possibly send some sort of unmanned spacecraft to investigate.

The problem we face is the mind bending distance any spacecraft would have to travel to get there. To give you a bit of context, it would take Voyager 2, which is traveling at an insane 35,000 miles per hour, approximately 75,000 years to reach it.

But, with technology moving as fast as it is, who knows, maybe we’ll learn a lot more about this exoplanet within our lifetimes!