The Astronomical Journal

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Six Billion Earth-Like Planets Could Exist in Galaxy

June 25, 2020
ExoNews Editor

Article by Sean Martin June 17, 2020 (express.co.uk)

• Searching through data from NASA’s planet hunting telescope Kepler, scientists from the University of British Columbia published a study in The Astronomical Journal estimating the likelihood of rocky Earth-like worlds which could contain water, within the Milky Way galaxy. A planet must also orbit a G-type star, like our Sun, and be positioned within the ‘Goldilocks Zone’ – the region around a star where it is neither too hot nor too cold – for life to exist.

• Astronomer Jaymie Matthews says, “Our Milky Way has as many as 400 billion stars, with seven per cent of them being G-type. So approximately six billion stars may have Earth-like planets in our Galaxy.” Researcher and co-author Michelle Kunimoto uses a technique known as ‘forward modelling’. “I started by simulating the full population of exoplanets around the stars Kepler searched. I marked each planet as ‘detected’ or ‘missed’ depending on how likely it was my planet search algorithm would have found them. Then, I compared the detected planets to my actual catalog of planets. If the simulation produced a close match, then the initial population was likely a good representation of the actual population of planets orbiting those stars.”

• Kunimoto also limits the possible number of habitable exoplanets where there exists a “radius gap”, “[I]t is uncommon for planets with orbital periods [of] less than 100 days to have a size between 1.5 and two times that of Earth,” says Kunimoto. “My calculations place an upper limit of 0.18 Earth-like planets per G-type star.” Previous estimates have suggested that there could be as few as 0.02 Earth-like planets per Sun-like star.

There are as many as 400 billion stars in the Milky Way galaxy alone, meaning there could be trillions of planets. As is evident from our solar system, the majority of these planets would be lifeless and barren, but billions could still be hospitable for life, according to new research. Scientists from the University of British Columbia (UBC) have searched through data from NASA’s planet hunting telescope Kepler to determine the likelihood of Earth-like planets – rocky worlds which could contain water.

To be considered Earth-like, the planet must also orbit a star like our Sun, known as a G-type star, according to the research published in The Astronomical Journal.

It also has to orbit the star in what is known as the Goldilocks Zone – the region around a star where it is neither too hot nor too cold for life to exist.
UBC researcher Michelle Kunimoto, co-author of the new study, said: “My calculations place an upper limit of 0.18 Earth-like planets per G-type star

“Estimating how common different kinds of planets are around different stars can provide important constraints on planet formation and evolution theories, and help optimise future missions dedicated to finding exoplanets”.

UBC astronomer Jaymie Matthews: “Our Milky Way has as many as 400 billion stars, with seven per cent of them being G-type.
“That means less than six billion stars may have Earth-like planets in our Galaxy.”

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Near-Earth Objects Could Be Used by Extraterrestrials ‘To Watch Our World,’ Stunning Study Suggests

October 11, 2019
ExoNews Editor

Listen to “E122 10-11-19 Near-Earth Objects Could Be Used by Extraterrestrials ‘To Watch Our World,’ Stunning Study Suggests” on Spreaker.

Article by Chris Ciaccia September 30, 2019 (foxnews.com)

• Although Earth only has one moon, it does have other miniature natural satellites locked its orbit, known as “co-orbital objects.”

• According to a new study entitled: “Looking for Lurkers: Co-orbiters as SETI Observables”, recently published in the American Astronomical Society’s The Astronomical Journal, these space rocks could be hiding grounds for an advanced extraterrestrial civilization, given their small size and close proximity to the planet. The study notes, “These near-Earth objects provide an ideal way to watch our world from a secure natural object… that provides resources an ETI [extraterrestrial intelligence] might need: materials, a firm anchor, and concealment.”

• The study’s sole author, James Benford, says that there could be hundreds, or even thousands, of stars that have been close enough to the Earth throughout its history for a potential intelligent civilization to make contact. Such a civilization may have seen on the Earth single-celled organisms or possibly dinosaurs, depending upon when they viewed them. Benford adds that there’s a chance that the technology they used to keep tabs on Earth could still be there. “This is essentially extraterrestrial archaeology I’m talking about.”

• Paul Davies, a physicist and astrobiologist at Arizona State University who was not involved in the study, said that aside from looking for extraterrestrial technology, studying co-orbitals might yield some promising finds. Says Davis, “[I]f it costs very little to go take a look, why not? Even if we don’t find E.T., we might find something of interest.”

• China has plans to explore the “constant companion of Earth” asteroid 2016 HO3.

Although Earth only has one moon, it does have other natural satellites, including asteroid 2016 HO3, known as a “co-orbital object.” These tiny celestial objects could be an “attractive location for extraterrestrial intelligence,” according to a new study.

The research suggests that these space rocks could be hiding grounds for an advanced civilization, given their small size and close proximity to the planet.

“These near-Earth objects provide an ideal way to watch our world from a secure natural object,” the study’s abstract reads. “That provides resources an ETI [extraterrestrial intelligence] might need: materials, a firm anchor, and concealment. These have been little studied by astronomy and not at all by the Search for Extraterrestrial Intelligence (SETI) or planetary radar observations.”

The study’s sole author, James Benford, told Live Science that it’s possible that there could be hundreds, or even thousands, of stars that have been close enough to the Earth throughout its history for a potential intelligent civilization to make contact.

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