Category: Exoplanets

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The habitable zone of a planet(s)

This is my unprofessional view. I do stand by it with my best knowledge of this field in planetary science. My knowledge might be outdated or wrong, resulting in me getting the wrong conclusions in this article. You have been warned.

The problem with the habitable zone of a planet

I dislike it when I see the news that a planet has been found around a star. Only to see later in that same news that the planet is a dwarf star giving out minimal amount of light and heat. There seems to be minimal requirement for live to exist in the universe. I don’t know if this has been studied in any details or if there have been any study into this matter in recent years. There is a lower limit on were life can exist and there is a upper limit on this same scale.

The lower limit and the upper limit

In my personal view this star classes can support life. There are limits within those classification.

Lower limit

Class M (?)
Class K
Class G
Class F
Class A
Class M (red giants, supergiants)

Lower limit

The lower limit of stars might support life if the conditions allow for it. This might not happen in majority of any star system that falls into the lower limit. If life exists around such planet in a star system that falls into the lower limit that life might only be plants that can deal with cold temperatures and long winters. Animal life on such planet should be expected to be limited to not existing at all. This goes both for ocean and land animal life.

Upper limit

All of this classes might have their own limit and not all star systems that have planets support life due to random reasons. No dwarf stars (class L, Y, T, M). Any star that is at the end of its life span might have had life in the past, it however should be expected to be extinct at this point in the star life cycle. The upper class of stars is more complicated as they radiate more energy out and have a shorter life span than smaller stars. A life can evolve around such star but in the time needed for it to evolve to a civilization levels are limited because of the time needed until that happen.

There’s no guarantee for life in a star system

While a star might be favourable to life that alone is not a guarantee in any way that a star system is going to have any life. A lot of things can go wrong in a planet formation that results in no life or atmosphere that can support life. I don’t know what starts life in a star system but it is a sequence of events that has to happen each time life gets going on a planet in any star system that has life.

The complex life problem

While life might exist in a star system it does not have to be animal life. There might be planets out there with nothing but plants and insects on them and no animals. What path evolution takes on each planet is based on random factors that are impossible to predict.

The Venus problem

Venus is a dead planet in more than just one way. When it formed something did go horribly wrong during its formation or soon after it formed. This seems to have happened early on and there is a good chance that life never took hold on Venus and it never had any water to start the carbon cycle. According to this article and based on measurements Venus magnetic field flares up for a short period of time, this suggests that whatever happened to Venus is related to the planet core and issues that it is having. In our solar system Venus should be full of jungle life today and possibly hosting a civilisation on its own. Something like humans or perhaps not. Whatever happened resulted in Venus resulted in Venus being a dead planet and he has remained like this for billions of years.

The Mars problem

Mars never had any life. Its too small as a planet to support life and due to a large eruption in its past its core died and along with it everything that might have been on its surface. There is a chance that before the core of Mars core died due to the eruption of Olympus Mons and other volcano activity. Other reasons for Mars core dying are also possible, among them greater heat loss due to Mars being a smaller planet. Being a greater distance from the Sun in our solar system Mars never had any chance of supporting life. In other solar systems where the planetary evolution is different and Mars sized planet might be closer to its star there is a small chance a life might exists for as long the planet is able to maintain its magnetic sphere.

The planet problem

There are many factors that have to add up for a life to happen in a solar system. Sometimes those factors exist in a solar system and sometimes they are missing in the formation process. How and why are not known to anyone and it is the biggest question that humans have unanswered. An answer might appear in the centuries ahead if humans survive current global warming crises.

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Trappist-1 has no life, it’s a dead star system

I see in the news that scientists have now claimed that TRAPPIST-1 has possibly chance of two Earth like planets. This is wrong in my view and the reason for that is this.

  • The TRAPPIST-1 star system is too cold for life. That means it doesn’t have the energy output to start life. The light energy from the star is too little. It’s simply too little light on any of the planets to get life going.
  • There is too much radiation in this star system. Dwarf stars, specially Ultra-cool dwarfs have more radiation as energy output then just light. This means higher x-ray output from the star.
  • The planets are too close together. The planets them self are probably geologically unstable. It is highly likely that all of the inner planets have high rate of volcanism (like the one found on Earth) that destroys and rebuilds oceans and lakes in matter of centuries. Possibly on shorter time scale.

Not every star system in the universe has the ability to get life going and Trappist-1 is one of those star systems. The same goes for every other dwarf star system out there. They are all too cold to support life. If scientists want to search for life they need to focus on stars that are like or close to our own sun in make and energy output. I don’t know if O-type and down to A-type of stars can support life due to their size, radiation profile and amount of energy that they push out every second. In my view life is limited to K-type and up to F-type of stars. The Sun (Sol) is a G-type star.

The discussion about life in space has been bothering me for a long time because it is based on the assumption that life can exist everywhere without any limits. That is a wrong view to have in my view. The rule that I have in this is that there are more dead planets (without life) out there than there are planets with life.

Reading the study shows that it is based on a guesswork or highly limited data that is giving them false results in their models. The problem that I am facing is that I don’t have the hardware (or the time) to study this my self to disprove them. If I did, then I would disprove them soon as I could. But I can’t and that’s the end of that.

The news article that sparked me writing this article.

Two planets in unusual star system are very likely habitable, scientists say (The Guardian)

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Exoplanet found around Alpha Centauri

This has been in the news all week. Scientists have found exoplanet around Alpha Centauri-B. This planet is in highly close orbit around Alpha Centauri-B. While this planet it self does not support life in any form. It opens up the possiblity that Alpha Centauri-A and B might have planets with life on them. Earth has life and is not so unique in my view.

This also makes Alpha Centauri A and B prime targets for searching alien civilizations close to our own solar system. But Alpha Centauri is just 4.37 light years away from Earth. But that means any radio signals are just 4.37 months reaching Earth (give or take). This also makes for a better signal detection at this short distance. If there is any civilization on Alpha Centauri A or B we have no way of knowing it state of technical levels. They might be more advanced then us, or they might be less advanced then us. Or they might still be in caves and really primitive. There is no way to know for sure. There is also a possibility that just life might exist in Alpha Centauri A-B system. But without any civilization at all. There is also chance if there was a civilization in the Alpha Centauri A-B solar system that it is long gone for one reason or other. Whatever the case actually is. This planet is a good hope that more planets might exist just 4.37 light years away from Earth.

But one thing is clear. We are never going to know without science studies in that direction. It is also my view that we need to study our closest star better then we already do. This applies mostly to the stars that are close to our own sun in size and brightness. Since the chance of finding planets like our Earth is highest around such stars. Rather then larger and heavier stars. Like blue giants and such. In that case. I think there might be planets around Sirius (8.6 light years away). But I do not think any such planet is likely to have any life on them. But I might be totally wrong in this estimate. But the only way to find out for sure is to study space, as it is human race most important step into the future.

News about this discovery

Next Door Neighbors? Earth-Sized Planet Discovered in Nearest Star System to Us (Universe Today)
Exoplanet around Alpha Centauri is nearest-ever (BBC News)

Technical information

Alpha Centauri 3 (Solstation)
Sirius 2 (Solstation)
Alpha Centauri (Wikipedia)