There may be as many as one Earth-like planet for every five Sun-like stars in the Milky way Galaxy, according to new estimates by University of British Columbia astronomers using data from NASA's Kepler mission.
To be considered Earth-like, a planet must be rocky, roughly Earth-sized and orbiting Sun-like (G-type) stars. It also has to orbit in the habitable zones of its star -- the range of distances from a star in which a rocky planet could host liquid water, and potentially life, on its surface.
"My calculations place an upper limit of 0.18 Earth-like planets per G-type star," says UBC researcher Michelle Kunimoto, co-author of the new study in The Astronomical Journal. "Estimating how common different kinds of planets are around different stars can provide important constraints on planet formation and evolution theories, and help optimize future missions dedicated to finding exoplanets."
According to 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."
Previous estimates of the frequency of Earth-like planets range from roughly 0.02 potentially habitable planets per Sun-like star, to more than one per Sun-like star.
One of the biggest and longest-standing questions in the history of human thought is whether there are other intelligent life forms within our Universe. Obtaining good estimates of the number of possible extraterrestrial civilizations has however been very challenging.
A new study led by the University of Nottingham and published today in The Astrophysical Journal has taken a new approach to this problem. Using the assumption that intelligent life forms on other planets in a similar way as it does on Earth, researchers have obtained an estimate for the number of intelligent communicating civilizations within our own galaxy -- the Milky Way. They calculate that there could be over 30 active communicating intelligent civilizations in our home Galaxy.
I had thought that our solar system was considered really weird since the gas giants didn't eat everything in the inner system.
This study would say otherwise though.
It's been 32 years since one of MN's four major sports teams has been to the Championship/Superbowl.
Every single year is failure until we win one. 4 teams, 32 years. That's roughly 128 consecutive failed seasons.
Basically, they posit that almost every star has a planet(s). Basically stars are created with an accretion disk which leads to planet formation.
They have a couple ways to identify the planets:
- Star wobble: The planets tug on their sun and they wobble ever so slightly.
- Transit: Planet passes in front of a star and it dims ever so slightly.
Hell, some of our nearest star neighbors have planets, so it doesn't seem to be unique. I think Trappist has like 8 planets and it's only 40-50 light years away.
I like some British scientists thoughts on this: Life like us would seem to be very rare. Need to be in a safe zone relative to the sun, relative to the galaxy's core, relative to supernova, or other life killing sources. He seemed to think it was like 1-2 advanced life per galaxy.
Moses Scurry wrote: ↑Tue Apr 13, 2021 11:47 am
Basically, they posit that almost every star has a planet(s). Basically stars are created with an accretion disk which leads to planet formation.
They have a couple ways to identify the planets:
- Star wobble: The planets tug on their sun and they wobble ever so slightly.
- Transit: Planet passes in front of a star and it dims ever so slightly.
Hell, some of our nearest star neighbors have planets, so it doesn't seem to be unique. I think Trappist has like 8 planets and it's only 40-50 light years away.
I like some British scientists thoughts on this: Life like us would seem to be very rare. Need to be in a safe zone relative to the sun, relative to the galaxy's core, relative to supernova, or other life killing sources. He seemed to think it was like 1-2 advanced life per galaxy.
Then he said, that's a pretty big responsibility.
fascinating subject. very difficult to wrap your mind around the enormity of the universe though.
Are There More Grains of Sand Than Stars?
This question comes from Sheldon Grimshaw. “I’ve heard that there are more stars in our Universe than there are grains of sand on all the beaches on Earth. Is this possible?” Awesome question, and a great excuse to do some math.
As we learned in a previous video, there are 100 to 400 billion stars in the Milky Way and more than 100 billion galaxies in the Universe – maybe as many as 500 billion. If you multiply stars by galaxies, at the low end, you get 10 billion billion stars, or 10 sextillion stars in the Universe – a 1 followed by 22 zeros. At the high end, it’s 200 sextillion.
These are mind bogglingly huge numbers. How do they compare to the number of grains of sand on the collective beaches of an entire planet?
Moses Scurry wrote: ↑Tue Apr 13, 2021 11:47 am
Basically, they posit that almost every star has a planet(s). Basically stars are created with an accretion disk which leads to planet formation.
They have a couple ways to identify the planets:
- Star wobble: The planets tug on their sun and they wobble ever so slightly.
- Transit: Planet passes in front of a star and it dims ever so slightly.
Hell, some of our nearest star neighbors have planets, so it doesn't seem to be unique. I think Trappist has like 8 planets and it's only 40-50 light years away.
I like some British scientists thoughts on this: Life like us would seem to be very rare. Need to be in a safe zone relative to the sun, relative to the galaxy's core, relative to supernova, or other life killing sources. He seemed to think it was like 1-2 advanced life per galaxy.
Then he said, that's a pretty big responsibility.
fascinating subject. very difficult to wrap your mind around the enormity of the universe though.
Are There More Grains of Sand Than Stars?
This question comes from Sheldon Grimshaw. “I’ve heard that there are more stars in our Universe than there are grains of sand on all the beaches on Earth. Is this possible?” Awesome question, and a great excuse to do some math.
As we learned in a previous video, there are 100 to 400 billion stars in the Milky Way and more than 100 billion galaxies in the Universe – maybe as many as 500 billion. If you multiply stars by galaxies, at the low end, you get 10 billion billion stars, or 10 sextillion stars in the Universe – a 1 followed by 22 zeros. At the high end, it’s 200 sextillion.
These are mind bogglingly huge numbers. How do they compare to the number of grains of sand on the collective beaches of an entire planet?
Was reading something really interesting today that kinda fits this thread.
Basically it took 300 million years after the late accretion impacts for us to go from prebiotic soup to the RNA world. But in this early period our Earth was extremely active (geologically) so anything that came close was being destroyed because of this activity. It was thought that life from prebiotic soup to cyanobacteria should've taken less than 10 million years (high end) to "out run" this eventual destruction due to the passage of the entire ocean through deep-sea vents.
That number is astoundingly low. 10 million years is not a long time to form life during the life of a planet.
It's been 32 years since one of MN's four major sports teams has been to the Championship/Superbowl.
Every single year is failure until we win one. 4 teams, 32 years. That's roughly 128 consecutive failed seasons.
Mysterious radio waves coming from the heart of the Milky Way baffle astronomers
Astronomers have detected mysterious radio waves coming from the center of the Milky Way, but so far they have no idea what's causing it, according to a new study published Tuesday in the Astrophysical Journal.
A team of scientists from across the world discovered the object using the CSIRO radio telescope in Western Australia. Ziteng Wang, the lead author of the study and a PhD student at the University of Sydney, said in a press release that they initially believed it could be a spinning dead star called a pulsar, but its signal didn't match what they expected from those types of celestial objects.
"The strangest property of this new signal is that it is has a very high polarisation," Wang said. "This means its light oscillates in only one direction, but that direction rotates with time."
"The brightness of the object also varies dramatically, by a factor of 100, and the signal switches on and off apparently at random," Wang added. "We've never seen anything like it."
The radio signal — named ASKAP J173608.2-321635 after its coordinates — was "unique" because it started out invisible, then it turned bright and faded away before reappearing again, said Tara Murphy, who is Wang's PhD supervisor and professor at the Sydney Institute for Astronomy and the School of Physics.
"This behaviour was extraordinary," she said.
The scientists detected six radio signals from the source over nine months in 2020 and tried to find the object in visual light, but found nothing. They opted to use the CSIRO radio telescope and failed to recognize the source.
According to the press release, the signals don't fit any currently understood pattern of variable radio source, and it could suggest a new class of stellar object.
"The information we do have has some parallels with another emerging class of mysterious objects known as Galactic Centre Radio Transients, including one dubbed the 'cosmic burper,'" said Wang's co-supervisor, David Kaplan, a professor from the University of Wisconsin-Milwaukee.
"While our new object, ASKAP J173608.2-321635, does share some properties with GCRTs there are also differences. And we don't really understand those sources, anyway, so this adds to the mystery," he said.
As scientists continue to keep an eye out for more clues, sources from other radio signals have been detected in recent months. In May, NASA traced the source of mysterious fast radio bursts sending signals to Earth.
