Is K2-18b an inhabited planet? Many people say "no".

  Is K2-18b an inhabited planet? Many people say "no". 

The K2-18b is a mini Neptune. The planet's mass is about 8 times of Earth. And the distance to that planet is 124 ly. The JWST found some "weak signs of life" on that planet. K2-18b habitable zone but that doesn't mean that there are lifeforms. 

The temperature of K2-18b is about zero Celsius. There is no ocean in that planet's atmosphere. But there is a water vapor. But the planet itself is dry. And that means there are no endemic advanced lifeforms. 

The JWST telescope found these elements from K2-18b's atmosphere. 

-Methane

-Carbon dioxide

-Hydrogen

-and probably dimethyl sulfide from that planet's atmosphere. 

In some rumors, there are some kind of radio signals detected from that exoplanet. Those rumors are the result of misunderstandings. The "signs of life" that the JWST telescope sees are the gasses that JWST saw in that planet's atmospheric spectrum. Those signs are interesting. But they are not straight technosignals. 

The radio or techno signals from dry planets that cannot host life can mean that something that comes outside that solar system made the base on that planet. That is one thing that we should think about. When we research the signals that the origin is or seems to be outside our solar system. 

Same way. We can conclude that "weak techno signals" are signs of just starting industrialization. But if those signs come from a dry world. That cannot be habitable. That could also tell about the alien base on those planets. 

"The most common “sized” world in the galaxy is a super-Earth, between 2 and 10 Earth masses, such as Kepler 452b, illustrated at right. But the illustration of this world as “Earth-like” in any way may be mistaken, as it’s more likely to either have a large, volatile gas envelope, making it a mini-Neptune, or to be a hot, stripped planetary core: like a scaled-up version of Mercury." (BigThink.com/Is K2-18b an inhabited ocean world? Don’t bet on it)

"When starlight passes through a transiting exoplanet’s atmosphere, signatures are imprinted. Depending on the wavelength and intensity of both emission and absorption features, the presence or absence of various atomic and molecular species within an exoplanet’s atmosphere can be revealed through the technique of transit spectroscopy. JWST cannot get spectra for Earth-sized planets around Sun-like stars, but Habitable Worlds Observatory finally will". (BigThink.com/Is K2-18b an inhabited ocean world? Don’t bet on it)

"The CHEOPS mission discovered three planets around the star Nu2 Lupi. The innermost planet is rocky and contains only a thin atmosphere, while the second and third planets discovered have large, volatile-rich envelopes. Although some are still calling them super-Earths, it’s very clear that not only are they not rocky, but most of the planets we call super-Earths are not like Earth at all in any meaningful way. This extends to all exoplanets with a radius above 1.7 Earth radii, with many of smaller sizes still having hydrogen and helium envelopes". (BigThink.com/Is K2-18b an inhabited ocean world? Don’t bet on it)

"This plot shows the spectrum, from 0.8-5.0 microns, of exoplanet K2-18b as taken with JWST. The signal is shown with data points with error bars; the interpretation of the signal by the discovering group is shown alongside it." (BigThink.com/Is K2-18b an inhabited ocean world? Don’t bet on it)

"What do planets outside our solar system, or exoplanets, look like? A variety of possibilities are shown in this illustration. Scientists discovered the first exoplanets in the 1990s. As of 2023, the tally stands at just over 5,000 confirmed exoplanets. None are known to be inhabited, but a few raise tantalizing possibilities: largely among the Earth-sized planets, not the super-Earth-sized ones". (BigThink.com/Is K2-18b an inhabited ocean world? Don’t bet on it)

But then I must return to the BLC-1 from Proxima B. 

The radio signal from Proxima Centauri B can have multiple origins. They could be some kind of plasma reflection from that planet's Van Allen belt. When some extraordinarily strong supernova blast happens that thing can send radio waves to Proxima B:s plasma belts. 

The Proxima B is a dry quite cold exoplanet. The surface temperature average is -39C. That means there could be oceans inside the ice. But there are no, at least endemic civilizations. This thing makes the Proxima B signal even more interesting than it has been. The thing that makes the BLC-1 signal interesting is that it does not repeat. The unique types of signals like BLC-1 and WoW! are the things that make them interesting. 

What could be the origin of the radio signals?

1) The signal could be a reflection from plasma rings around that planet. 

2) Signals can reflect anywhere between that planet and Earth.

3) Signal is created something that we cannot even imagine.

So if there are some kind of radio signals from that direction. The conditions on that planet make this situation quite complicated because that signal probably doesn't come from Proxima B. Or even if that signal comes from that direction could be a reflection from its Van Allen belt. The plasma belt that surrounds planets can reflect radio signals. And the origin of those signals can be anywhere in space. 

There is one interesting hypothesis about the WoW! and BLC-1 signals. 

One possibility is the probe that is sent by some other civilization. If we think that the signal happens only once there is the possibility that the signal can be the call signal. In that case, the probe acts like a computer. When it connects to the internet. It sends the call signal to the base or server that it is ready, and then the server or base sends the unique channel for the probe. 

The idea is that the probe, controlled by highly advanced AI has been in shutdown condition while it travels in space. When it arrives in the solar system, Proxima Centauri. It wakes up and makes its landing process fully automatic. Then that probe sends a signal that it's ready for work. 

In that hypothesis, the alien civilization that sent that probe saw the radio transmissions from the direction of Alpha Centauri. They might think that the signals are coming from Alpha Centauri, not the yellow star behind that triple star. And then they send probes to that solar system seeking another civilization. The idea of that hypothesis is that also humans are sending techno signatures around the universe. 

https://en.wikipedia.org/wiki/Proxima_Centauri_b

https://en.wikipedia.org/wiki/K2-18b

https://en.wikipedia.org/wiki/BLC1

https://en.wikipedia.org/wiki/Wow!_signal