Space

Up to 300 million planets in the Milky Way may be habitable

Up to 300 million planets in t...
According to a new study, there could be 300 million potentially habitable planets (like Kepler-186f) in our galaxy
According to a new study, there could be 300 million potentially habitable planets (like Kepler-186f) in our galaxy
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According to a new study, there could be 300 million potentially habitable planets (like Kepler-186f) in our galaxy
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According to a new study, there could be 300 million potentially habitable planets (like Kepler-186f) in our galaxy

Based on data from the Kepler Space Telescope and the Gaia mission, there may be up to 300 million habitable planets in the Milky Way galaxy, according to a team of scientists from the SETI Institute, NASA, and other international organizations. The research not only gives a measurement of how many potentially life-bearing planets there are, it also provides a key factor in the Drake equation that estimates how many extraterrestrial civilizations may exist.

Written in 1961 by Dr. Frank Drake, the Drake equation is the most famous formula in the search for extraterrestrial technological civilizations that could potentially communicate with Earth using radio signals. The calculation is based on a number of factors, including the rate of star formation, the fraction of stars that have planets, how many habitable planets a star has, the number of planets that develop life, the number that produce intelligent life, the number that produce a technological civilization, and the life span of that civilization.

The problem is that none of these factors are known for certain. Some are only rough estimates and some are pure guess work. The result is that the Drake equation estimates that there are anywhere between one and 100 million technological civilizations in our galaxy – a range that isn't very helpful.

In an effort to refine things a bit, researchers used data from the Kepler exoplanet hunting mission to produce a more reliable estimate of one factor in the equation – how many habitable planets are there in the galaxy. To answer this, the study looked at exoplanets that are roughly the same size as the Earth, revolve around Sun-like stars of the same approximate age and temperature, and are in the habitable zone of their star where liquid water could exist.

This is similar to previous studies, but according to the SETI Institute, the new research refined the habitable zone factor by including not only the distance from the star, but also the amount of light the planet receives. This was achieved by combining the Kepler data with that of the Gaia mission, which measures the amount of energy the host star emits.

The result is an estimate that there may be up to 300 million potentially habitable planets in our galaxy, with some as close as 30 light years from Earth. However, this number may be further refined down or up as we gain a greater understanding of how the atmosphere of a planet can affect its ability to support liquid water. The researchers say they used a conservative estimate of this atmospheric impact for their analysis, which should help inform future exoplanet-hunting efforts.

"Knowing how common different kinds of planets are is extremely valuable for the design of upcoming exoplanet-finding missions," says study co-author Michelle Kunimoto. "Surveys aimed at small, potentially habitable planets around Sun-like stars will depend on results like these to maximize their chance of success."

The research was published in the Astronomical Journal.

Source: SETI Institute

10 comments
Babaghan
We are just an advanced breed of monkeys on a minor planet of a very average star. But we can understand the Universe. That makes us something very special.
piperTom
Now it's 300 million habitable planets! The SETI people may dream that this huge number improves their odds, but Enrico Fermi is still laughing. Just think: half of those 300,000,000 are going to be OLDER than Earth. In a galaxy some 11 billion years old, very many are going to be MUCH older than Earth. Why would other civilizations leave alone a nice neighborhood like Earth -- for hundreds of millions of years? Civilizations rise and fall; no kind of legal or cultural restriction could last. Even if there are only TWO other civilizations, they would get diversity just from age. They would have filled the galaxy with their probes, long before animals with opposable thumbs descended from the trees. Their poachers, scoundrels, religious cultists, treasure hunters, and plain nuts would have been here before the dinosaurs and thousands of more times after. Face it: intelligent life is stupendously rare.
Nobody
All these estimates are more hubris than science. So many conditions are required to make a planet habitable that even our own earth should have been ruled by dinosaurs instead of humans. These animals proved themselves much more successful than man. They had no reason to develop intellectually. Even after all these millennia we still have snakes, crocodiles, and turtles plus simpler life like bacteria and viruses. Mankind is just a flash in the pan anomaly who wouldn't even exist without a long series of mathematically impossible coincidences. Without carbon based fuels, concentrated metals and a 20% oxygen atmosphere, We would never have advanced on our own planet.
AlexEucare
300 Million potential planets in JUST the Milky Way!

That means, along with Two TRILLION galaxies in the "known" universe, statistically, WE ARE NOT ALONE
Kpar
I refer the authors of this study to the book "Rare Earth" by Peter Ward and Donald Brownlee. The Drake equation is absurdly optimistic- modern studies show that, rather than the 12 or 15 factors that describe a "habitable planet" there are probably more than 200 factors that must be met! Not the least of which is that the "Goldilock's Zone" that is exemplified by the area around a star that supports liquid water, there is also a GALACTIC Goldilock's Zone that is about one third of the galaxy, where there are not too many exploding stars- which would repeatedly sterilize star systems nearby. We are fortunate, indeed, to live where we live.
MikeofLA
If the conditions for life exist on 1:1000 of these planets, and microbial life rises on just 1:1000 of those, then advanced life is just 1:1000, and intelligent life is 1:1000, and then technologically advanced life is 1:1000 you're talking about a vanishingly small chance that there are any other civilizations out there.
JustSaying
I don't want to burst anyone's bubble, but, lets take the 30 light years away. If it has intelligent life, same as us or, more advance. The first thing is to send a message. If we could send it by light speed, it would take 30 years and that is without interference. They hear us and send a reply, another 30 years. That's 60 years for first contact. Baby steps folks! Our universe first! When we work out that problem, then reach for the stars.
Ines
As MikeofLA said 0.00001% chance is closer to the mark ~ 30 planets. But I believe should you throw in at least two Great Filters it would be closer to 0.0000001% ~ well, who wants to live on 1/3 of a planet - ah, seems we have it here. So maybe Andromeda then anyone?
Pokurcz
You guys should read The Three Body Problem before you send out any communications.
Douglas Bennett Rogers
UFO abductions aside, ANY discovery of exobiology would completely change the picture.