Stop looking for an ‘Earth 2.0’, say scientists as they spot an even better ‘super-habitable’ world

Our planet is the best there is, right? Not necessarily, say Washington State University researchers who have compiled a list of 24 planets outside our Solar System that are not only similar to Earth, but may even be best than Earth.

The list, which is intended to be a “to-do” list for a group of powerful telescopes to be launched in the next few years, includes planets that are older, slightly larger, slightly warmer, and possibly wetter than Earth. Earth, and that orbit stars with a longer lifespan than our Sun.

The researchers, whose work is published this week in the journal Astrobiology“I think the worlds on the list contain some that could be called” super habitable. ” That means they could be places where life could thrive more easily than on Earth.

Please indicate an MVP, the most valuable planet, which is likely larger than Earth and easier to detect than Earth-like planets.

If we want to find life elsewhere in the galaxy, then “super-habitable” planets may deserve a higher priority than most Earth-like planets, the researchers say.

How could another planet be more suitable for life than Earth? For an Earthman with only one point of reference, it seems like a crazy question.

Here you will find everything you need to know about finding “super-habitable” planets where life not only exists, but thrives.

Where are the ‘super habitable’ planets?

Unfortunately, all 24 planets are in star systems that are more than 100 light years from the Solar System. The researchers reviewed the list of the more than 4,500 known exoplanets in our Milky Way. They do not Look for life, but only for general conditions that would lead to complex life, defined as macroscopic multicellular life, such as animals, plants, and fungi.

How could a planet be more habitable than Earth?

We are living here.

We know that it is full of life.

There is biomass and biodiversity everywhere we look.

How could another planet be “better”? However, the environments of our planet have changed dramatically over time. The researchers argue that there could be regions of star and planet systems that could allow planets to be even better for life than our Earth. To a large extent they evaluated them considering:

• Astrophysics: the type of star they orbit and their lifespan.
• History of Earth: what kind of planet is it vs. the variability of the habitability of the natural history of our planet.

What happens to our Sun?

The Sun is a “type G” star. Our own ball of hot plasma has been happily fusing hydrogen and helium atoms for about 4.6 billion years and has another 5.4 billion years left before it runs out of fuel. Complex life, which is us, appeared on Earth between five and seven million years ago. So it took a while. What are the chances of complex life appearing during the 10 million year life of another G-type star? That’s unknowable, but it could be unlikely. The star could die before complex life began.

Therefore, the researchers say, we should also look for life on planets that orbit cooler “G-type” stars, with a longer life expectancy than our Sun, as well as “K-dwarf” stars, which are cooler, less massive and less luminous than our Doms. They have a lifespan of between 20 billion and 70 billion years. That could be the place to look for complex life because it will have had a much longer time to develop. After all, the Milky Way has been around for 13.5 billion years.

Taking into account the fact that a planet must be at its best to retain a magnetic field, which protects any life on its surface from lethal radiation, the researchers obtain a sweet spot for how old a planet should be. for Life Support; from five billion to eight billion years.

What happens to our planet?

Earth has certainly not been habitable for its entire existence. Ice ages, asteroid strikes, and changes in the chemical composition of Earth’s atmosphere (such as the “Great Oxidation Event” about 2.4 billion years ago) have affected the habitability of the Earth.

The researchers used Earth as a basis for establishing which planets might be “super habitable,” but they used some leeway. For example, they narrowed the list down to star systems and planets believed to have rocky planets orbiting within the host star’s “habitable zone,” the region around a star within which a planet needs to orbit for water to exist. liquid on its surface. Not too hot and not too cold, also called the “Goldilocks area”.

They also chose planets that are between 10% and 50% larger than Earth, that would have more habitable land, would have interior heating for longer, and would also have stronger gravity to maintain their atmosphere for longer.

Lastly, they chose slightly warmer planets with more humidity. After all, it is in the humid and warm rainforests on Earth that boast the greatest biodiversity.

So what is the most ‘super habitable’ planet?

Here’s the investigators’ shopping list:

• In orbit around a “K-type” dwarf star.
• About 5-8 billion years.
• Up to 1.5 times more massive than Earth and about 10% larger than Earth.
• The average surface temperature is about 5 ° C higher than on Earth.
• Humid atmosphere with O2 levels of 25 to 30%, the rest mainly inert gases (eg, N2).
• Scattered land / water distributed with many shallow water areas and archipelagos.
• Large moon (1–10% of the planet’s mass) at a moderate distance (10–100 planetary radii).
• It has plate tectonics or a similar geological / geochemical recycling mechanism, as well as a strong protective geomagnetic field.

Although none of the top 24 candidate planets meets all the criteria for “super-habitable” planets, largely due to a lack of data on moons, plate tectonics, etc., the closest researchers can get to establishing the MVP is a planet called KOI 5715.01.

About 1.8 times larger than Earth and about 5.5 billion years away, KOI 5715.01 orbits its star every 190 days.

Yet sadly, KOI 5715.01 is a whopping 2,964 light years from the Solar System.

Why do we need a list of “super-habitable” planets?

The launch is planned for the next few years, three very powerful space telescopes that will give us the opportunity to study distant exoplanets up close for the first time. The most famous is NASA’s James Web space telescope, which will launch on October 31, 2021, while the European Space Agency’s PLATO space telescope (2026) and NASA’s LUVIOR space observatory (which will launch in the 2030s) are also coming soon.

“With the next coming space telescopes, we will get more information, so it is important to select some targets,” said Dirk Schulze-Makuch, a geobiologist and professor at Washington State University and the Technical University of Berlin, who led the study. . “We have to focus on certain planets that have the most promising conditions for complex life.”

Can’t we just search for an ‘Earth 2.0’?

So far, much of the work on exoplanets has been done in the context of the search for an Earth-like “twin planet” somewhere in the Milky Way. So are we looking for ourselves? The very definition of that search is skewed: it is human-centered and Earth-centered.

“We have to be careful not to get stuck looking for a second Earth because there could be planets that might be more suitable for life than ours,” said Schulze-Makuch. “Sometimes it is difficult to convey this principle of super-habitable planets because we believe we have the best planet,” he added.

“We have a lot of complex and diverse life forms, and many that can survive in extreme environments … it’s nice to have an adaptable life, but that doesn’t mean we have the best of everything.”

Wishing you clear skies and wide eyes.