Super planets are bigger and more habitable than Earth, and astronomers discover billions more they think are out there

Astronomers now routinely discover Planets orbiting stars outside the solar systemThey are called the outer planets. But in the summer of 2022, teams are working at NASA Transiting a satellite to survey the outer planets It found a few interesting planets orbiting in the habitable zones of their parent stars.

one planet is 30% larger than Earth It orbits its star in less than three days. the other 70% larger than Earth and strength It hosts a deep ocean. These two outer planets are super earthLarger than Earth, but smaller than ice giants such as Uranus and Neptune.

I Professor of astronomy Who studies galactic nuclei, distant galaxies, astrobiologyAnd the outer planets. I am closely following the search for planets that might host life.

Earth is still the only place in the universe that scientists know is home to life. It would seem logical to focus the search for life on clones of Earth –Planets with properties close to Earth. But research has shown that astronomers’ best chance of finding life on another planet is likely to be on a super-Earth similar to the one found recently.

A super-Earth is any rocky planet larger than Earth and smaller than Neptune. Image credit: Aldaron, CC BY-SA

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Most giant planets orbit cold dwarf stars, which are less massive and live much longer than the Sun. There are hundreds of gorgeous dwarf stars for every star like the Sun, and scientists have found super-terrestrial planets orbiting around them 40% of the Magnificent Dwarves They have looked at him. Using this number, astronomers estimate its existence tens of billions of the super-planets in habitable regions where liquid water can exist in the Milky Way alone. Since all life on Earth uses water, water is believed to be essential for life.

Based on current expectations, about a One third of the outer planets They are super-terrestrial planets, making them the most common type of exoplanet in the Milky Way. Only the closest Six light years from Earth. You might even say that our solar system is unusual because it does not have a planet with a mass between Earth and Neptune.

Another reason that super-Earths are ideal targets in the search for life is that it is much easier Detection and study of the Earth-sized planets. There are two methods astronomers use to discover exoplanets. One looks for a planet’s gravitational effect on its parent star, while the other looks for a brief dimming of the star’s light as the planet passes in front of it. Both detection methods are easier with a larger planet.

Super Habitable Earth

More than 300 years ago, the German philosopher Gottfried Wilhelm Leibniz argued that the Earth was “The best of all possible worlds. Leibniz’s argument was intended to address the question of why evil exists, but modern astrobiologists have explored a similar question by asking what makes a planet hospitable to life. It turns out that Earth is not the best of all possible worlds.

Due to Earth’s tectonic activity and changes in the brightness of the Sun, the climate has shifted over time from the boiling temperature of the ocean to the extreme cold of the planet. Earth has been uninhabitable for humans and larger creatures for most of its 4.5 billion year history. Simulation refers to the long-term The habitability of the earth was not inevitableBut it was a matter of chance. Humans are literally lucky to be alive.

The researchers found a file Feature List Which makes a planet very conducive to life. Large planets are more likely to be geologically active, a feature that scientists believe will be Promote biological development. So a more habitable planet would have roughly twice the mass of Earth and be 20 to 30 percent more massive. It would also have oceans shallow enough for light to stimulate life all the way to the sea floor and an average temperature of 77 degrees Fahrenheit (25 degrees Celsius). It would have a thicker atmosphere than the Earth’s, which would act as an insulating cover. Finally, such a planet would orbit a star older than the Sun to give life longer to evolve, and would have a strong magnetic field Protects from cosmic radiation. Scientists believe that these traits combined will make the planet habitable.

By definition, a super-Earth possesses many of the attributes of a super-habitable planet. So far, astronomers have discovered Twenty super-Earths Which is, if not the best of all possible worlds, theoretically more habitable than Earth.

Recently, there has been an exciting addition to the inventory of habitable planets. Astronomy scientists The discovery of exoplanets began that was expelled from their star systemsand there can be Billions of them Wander the Milky Way. If the giant Earth was expelled from its star system and had a dense atmosphere and a watery surface, it could It preserves life for tens of billions of yearsmuch longer than life can last on Earth before the sun dies.

Detecting life on super-Earth

To discover life on distant exoplanets, astronomers will search for vital fingerprints, By-products of biology that can be detected in the planet’s atmosphere.

NASA agency James Webb Space Telescope It was designed before astronomers discovered exoplanets, so the telescope was not optimized for exoplanet research. But she is able to do some of this science is due to her Targeting two potentially habitable super-Earths In its first year of operations. Another group of super-Earths with huge oceans that have been discovered in the past few years, in addition to the ones discovered this summer, are also Compelling goals for James Webb.

But the best chances are to find the signs of life Atmosphere of an exoplanet It will come with the next generation of giant ground telescopes: 39 meter very large telescopeThe Thirty meters telescope and the Giant Magellan Telescope with a length of 24.5 meters. These telescopes are all under construction and scheduled to begin collecting data by the end of the decade.

Astronomers know the ingredients for life are there, but habitable doesn’t mean it’s inhabited. Until researchers find evidence of life elsewhere, it is possible that life on Earth was a unique accident. While there are many reasons why the world is habitable It will have no signs of lifeIf, in the coming years, astronomers look at these super-habitable planets and find nothing, humanity may be forced to conclude that the universe is a lonely place.Conversation

This article has been republished from Conversation Under a Creative Commons License. Read the original article.

image rights: NASA Ames/JPL-CalTech