Attention human. You are receiving an interstellar radio transmission. And it could be coming from one of the nearest exoplanets, Proxima Centauri b. What conditions make this planet a candidate for alien life?
What types of civilizations could have flourished there? And should we expect them to be knocking on Earth’s door any day now?
At a distance of 4.2 light-years away, Proxima Centauri is one of the closest stars to our Sun. In 2016, a planet was discovered orbiting in Proxima Centauri’s Goldilocks zone. That’s where conditions for liquid water could exist.
Meet Proxima b. A planet that registers at 0.87 on the Earth Similarity Index. This scale measures how similar a planet or moon is to Earth, and anything above 0.8 is considered “Earth-like.” As another example, Mars has an ESI of 0.64.
In 2020, astronomers recorded a mysterious radio signal coming from the direction of Proxima Centauri. Could it be that an alien civilization was attempting to contact us?
Though Proxima b is similar to Earth, lifeforms on this alien planet would likely develop very differently. For starters, the planet is about twenty times closer to its star than Earth is to the Sun. And it only needs 11.2 days for one full revolution.
That’s a lot of New Year’s celebrations. But still, Proxima b receives about the same amount of solar energy as Earth. That’s because Proxima Centauri is an M-type red dwarf star.
Compared to our G-type Star, these stars are generally cooler in a range of 2,200-3,200 °C (4,000-5,800 °F). But there would be some extreme conditions that an alien civilization would have to adapt to.
These extraterrestrials would need to be able to withstand radiation. And lots of it. The planet receives about 400 times more X-rays than Earth. And dwarf stars like Proxima Centauri give rise to coronal mass ejections that would blast the planet with lethal radiation.
Without a protective atmosphere, this would be deadly for any potential lifeforms. Another challenge for a Proxima b civilization would be tidal locking. That’s when a planet takes the same amount of time to spin on its axis as it does to orbit its star.
Imagine living where you permanently face the scorching Sun while the other side of Earth is in a constant state of frozen darkness. This is what life would be like on this exoplanet.
Civilizations on Proxima b would likely develop in the so-called terminator zones. These are the strips of twilight between the dayside and nightside. Here, winds would carry warm air and create life-supporting conditions. And aliens would build thermal reactors with the mix of cool and hot water to have that H2O always available.
If civilizations appeared on either of the sides of the terminator zone, they’d need to develop different survival tactics. But collaboration and unity could allow them to supply each other with heat or ice effectively.
And if a civilization developed on the light side, would they even know there were other stars or objects in the Universe? Would they even think about other life out in space? That brings us back to the radio signal the Breakthrough Listen project recorded in 2020.
This signal occupied a very narrow band of the radio spectrum at 982 MHz. This is startling because it’s a portion of the spectrum rarely used by human-made transmitters.
Researchers haven’t ruled out the possibility that these signals originated on Earth, but there are many unanswered questions.
One thing they are sure of, it didn’t come from a natural world. Only manufactured, or alien-made, technology seems to produce signals like that. So if an advanced civilization was trying to communicate with us from Proxima b, what would their society be like?
They could be a Type I civilization like us and use the energy available from their planet, like oil, wind or geothermal power. Or they could be a Type II civilization using energy on the scale of their planetary system. That would mean they were thousands of years more advanced than us.
Would they have developed complex languages and live in cities? Would they have democratic forms of governance? Or would they live under the rule of a dictator? You must have so many questions for our alien neighbors. And they would have so many questions for you. Or maybe they already know everything.
Unfortunately, we likely wouldn’t be able to visit them any time soon. Using current technologies, it would still take between 19,000 and 81,000 years to reach them. Of course, they could travel faster than the speed of light and get here first.
- “The biology of aliens: How much do we know?”. 2020. Big Think.
- “Here’s What The Climate Might Look Like On Proxima Centauri B – Universe Today”. 2020. Universe Today.
- “Here’s what we know about the signal from Proxima Centauri“. 2021. astronomy.com.
- “The Habitable Exoplanets Catalog – Planetary Habitability Laboratory @ UPR Arecibo”. 2021. phl.upr.edu.
- “Was This Mystery Radio Signal Really From Proxima Centauri? | Space | Earthsky”. 2020. Earthsky | Updates On Your Cosmos And World.