by Jacob Aron
There could be two Earth-like planets within cosmic spitting distance of our own. Both are likely too close to their star to host life, but the discovery opens the possibility of other planets in the system with more temperate climates.
Alpha Centauri is a binary star system just 4.3 light years away from our own. In 2012 astronomers announced that the system had a planet, which they dubbed Alpha Centauri Bb as it was apparently orbiting the smaller of the stars, Alpha Centauri B.
The team said it was a rocky world slightly more massive than Earth. But in 2013, other researchers called into question the existence of Bb, saying the evidence wasn’t good enough.
“If you ask anyone working in exoplanets, they would all have a different opinion about the existence of Alpha Centauri Bb,” says Brice-Oliver Demory of the University of Cambridge.
That’s why he and his colleagues have been using the Hubble Space Telescope to search for planet. They weren’t able to find it, but have instead seen hints of a second Earth-sized world in the system.
The original claim was based on the radial velocity method – a planet-hunting technique which looks at how the gravitational pull of a planet slightly wobbles its star. Demory’s Hubble search took a different approach, looking for signs of a dip in the light from Alpha Centauri B caused by the planet passing in front of, or transiting, the star. These two methods are independent of each other, so seeing Bb transit would reinforce the earlier patchy radial velocity data.
The original measurements suggested that Bb, if it exists, takes three or so days to orbit its star. But not all planets make transits as seen from Earth, because it depends on how the planet and star are aligned.
Demory’s team observed Alpha Centauri B in 2013 and 2014, for a total of 40 hours. The 2013 data showed signs of a transit consistent with Bb’s suggested orbital parameters, but it seemed to last slightly longer than expected, and the statistical validity of the signal disappeared when combined with the 2014 data. That doesn’t mean Bb isn’t there, just that if it exists, it is unlikely to transit as seen from Earth.
That still leaves a puzzle over what caused the 2013 signal. The team ruled out errors with Hubble itself or spots on the surface of the star, which can sometimes be mistaken for exoplanets.
They also dismissed the possibility of interference from Alpha Centauri A, the other star in the binary system, or from an unrelated, more distant star system that could have just been passing behind.
The only explanation left was that there is another planet in the system. The observations point to an Earth-sized planet with a year lasting no more than 20.4 days, putting it slightly further out than Bb but still scorchingly close to the star.
Astronomers have confirmed nearly 2000 exoplanets so far, and the evidence suggest many stars host multiple planets, just like our own solar system. That means confirming the discovery of one planet around Alpha Centauri B – even one with a hot, close orbit – hints at other planets in the system that might be more hospitable. “If you see one planet, the chance is there are other planets in the system,” says Demory.
“They work they’ve done holds tight; they give a very well balanced view on what this transit could be,” says Paul Wilson of the Paris Institute of Astrophysics in France. He’s not sure there is enough evidence yet to support a full discovery, but is keen to encourage the team. “I hope they will be able to detect an Earth-sized planet through the transit method. That would be fantastic.”
Unfortunately it’s going to be difficult to confirm either of these planets with our current generation of telescopes. Hubble could do it, but it would have to stare at Alpha Centauri for 20 days with no guarantee of finding anything, which would be seen as a waste of time for our most important space telescope, says Demory.
Upcoming instruments like the European Extremely Large Telescopeor the Cheops space telescope might be able to see the new planet, but the best option could be a small satellite dedicated to staring at Alpha Centauri. Such a mission would only cost around $2 million. “It could be crowdfunded,” says Demory. Anyone fancy chipping in to find our nearest neighbours?
We were wrong-100 billion habitable Earth-like planets in our galaxy alone
Estimates by astronomers indicate that there could be more than 100 BILLION Earth-like worlds in the Milky Way that could be home to life. Think that’s a big number? According to astronomers, there are roughly 500 billion galaxies in the known universe, which means there are around 50,000,000,000,000,000,000,000 (5×1022) habitable planets. That’s of course if there’s just ONE universe.
In fact, just inside our Milky Way Galaxy experts believe are some 400 BILLION STARS, but this number may seem small as some astrophysicists believe that stars in our galaxy could figure the TRILLION. This means that the Milky Way alone could be home to more than 100 BILLION planets.
However, since astronomers aren’t able to see our galaxy from the outside, they can’t really know for sure the number of planets the Milky Way is home to. They can only provide estimates.
To do this, experts calculate our galaxy’s mass and calculate how much of that mass is composed of stars. Based on these calculations scientists believe our galaxy is home to at least 400 billion stars, but as I mentioned above, this number could drastically rise.
There are some calculations which suggest that the Milky Way is home on an average between 800 billion and 3.2 trillion planets, but there are some experts who believe the number could be as high as eight trillion.
Furthermore, if we take a look at what NASA has to say, well find out how the space agency believes there are at least 1,500 planets located within 50 light years from Earth. These conclusions are based on observations taken over a period of six years by the PLANET—Probing Lensing Anomalies NETwork—collaboration, founded in 1995. The study concluded that there are way more Earth-sized planets than Jupiter-sized worlds.
So much space, so little information.
In 2013, Dr. Phil Yock, from the department of physics at the University of Auckland said how: “Kepler finds Earth-sized planets that are quite close to their host stars, and astronomers estimate that there are around 17 billion such planets in the Milky Way. These worlds are hotter than our planet, although some could be of a comparable temperature (and could, therefore, be habitable) if they are orbiting a cool star called a red dwarf.”
“Our proposal is to measure the number of Earth-mass planets orbiting stars at distances typically twice the Sun-Earth distance. Our planets will, therefore, be cooler than the Earth. By interpolating between the Kepler and MOA results, we should obtain a good estimate of the number of Earth-like, habitable planets in the Milky Way. We predict a number in the order of 100 billion.”
“Of course, it will be a long way from measuring this number to actually finding inhabited planets, but it will be a step along the way.”
The number seems to be increasing every year.
If we take a peek at the data provided by the Kepler space mission, we’ll find how astronomers believe approximately 40 BILLION Earth-sized planets orbiting habitable zones of Sun-like stars and red dwarfs in the Milky Way galaxy alone.
Since Kepler was launched in 2009, the space telescope has discovered a total of 4,034 potential alien planets, of which 2,335 are verified exoplanets.
Interestingly, some astronomers say that around 11 billion planets may be orbiting Sun-like Stars, while other believe this number is more like 100 billion.
In 2017 NASA made great progress in the search for alien planets. Their most noteworthy discovery was the solar system Trappist-1, home to SEVEN Earth-like planets who may even be home to alien life.
In June of 2017, NASA revealed a statement saying that they had discovered ten new planets outside of our solar system that are very likely of similar size and temperature as Earth and may even have life developed on their surface.
Scientists Found 234 Alien Civilizations
Aliens are like buses, you spend ages waiting for one and then 234 come along at once. Or at least, that’s what two astronomers from the Laval University in Quebec are suggesting.
Ermanno Borra and his graduate student Eric Trottier have analyzed over 2.5 million stars and galaxies for pulses of light emitted at regular intervals and discovered it in 234 stars similar in size to our Sun. The team believes that alien civilizations are behind those signals.
The researchers looked at the Fourier Transform (FT) of the light spectrum. The FT is a mathematical tool that allows us to work out where the components of a signal come from. If the light is a milkshake, by using the FT you get the recipe.
The FT analysis has found periodic modulated components which, according to the scientists, are caused by the super quick light pulses (less than a trillionth of a second) generated by Extraterrestrial Intelligence (ETI).
In the paper, available from the Publications of the Astronomical Society of the Pacific, they discard every other explanation such as instrumental effects, rotation of molecules, rapid stellar pulsations, and peculiar chemistry.
“We find that the detected signals have exactly the shape of an ETI signal predicted in the previous publication and are therefore in agreement with this hypothesis,” the researchers wrote in the paper.
“The fact that they are only found in a very small fraction of stars within a narrow spectral range centered near the spectral type of the Sun is also in agreement with the ETI hypothesis.”
These superfast pulses will have to be generated by incredibly powerful lasers, like the one at the Lawrence Livermore National Laboratory.
Interestingly, in previous publications Borra has stated that this area of astronomy is the least explored, which raises the question on why these aliens would all decide to communicate in such a complicated and energy-consuming way.
The researchers admit that although they believe aliens is the most likely explanation, this is yet to be confirmed.
The Stephen Hawking-backed project Breakthrough Listen will conduct follow-up observations of these 234 stars, but the team at UC Berkeley, where the project’s science program is based, invite people to be skeptical.
“The one in 10,000 objects with unusual spectra seen by Borra and Trottier are certainly worthy of additional study. However, extraordinary claims require extraordinary evidence.
It is too early to unequivocally attribute these purported signals to the activities of extraterrestrial civilizations,” the Breakthrough Listen team said in a statement.
Don’t Panic but There’s an 11% Chance Elon Musk’s Tesla Is on a Collision Course With Earth
I guess 11% is fairly low but then again any percentage is still a chance…the risk of satellites and other launched objects crashing back to Earth with potentially deadly consequences are becoming too regular now and not to mention the natural threats we already face from asteroids, comets etc..
via Science Alert:
It’s the darnedest thing, guys. Remember that Tesla owned by Elon Musk that SpaceX cavalierly launched into space last week? Well, it turns out that might not be the last we see of it.
In fact, according to a new analysis of the Roadster’s orbital trajectory, that stylish hunk of red metal, rubber, ‘Starman’, and other cool stuff is on track to make a number of close encounters with Earth – and ultimately, one day, it could even hit us.
That’s the assessment of Canadian astrophysicist Hanno Rein from the University of Toronto Scarborough, who, with fellow researchers, ran the numbers on what the Tesla’s invisible highway through space might look like, given what we know about orbital dynamics.
“We have all the software ready, and when we saw the launch last week we thought, ‘Let’s see what happens.’” Rein told Science.
“So we ran the [Tesla’s] orbit forward for several million years.”
Over that epic expanse of time (and space), it’s fair to say that a lot of things could happen – and the further ahead we estimate, the fuzzier the picture becomes, given how many gravitational factors could affect the overall trajectory of the vehicle (and the second stage of the Falcon Heavy rocket, to which it remains attached).
Nonetheless, the team’s simulations suggest the Tesla’s elliptical orbit around the Sun – which sees it repeatedly cross the orbits of Mars, Earth, and Venus – will make for several close encounters with Earth in the future, the first of which is expected to take place in 2091.
Looking further ahead, the good news is the researchers don’t foresee any possible impacts with Earth for the next thousand years at least – but they’re not offering any kind of firm guarantee on that.
“The bottom line is we can’t predict with certainty what’s going to happen after just a few hundred years, because it’s a chaotic orbit and we can only draw conclusions in a statistical sense,” Rein told CBS News.
Still, across some 240 simulations tracing the long-term dynamical evolution of the car’s possible orbital destinies, “roughly 50 percent are going to hit a planet in the next few tens of millions of years,” Rein figures.
To the extent their approach can quantify risk of a collision, the researchers say there’s a 6 percent chance the Tesla will collide with Earth within the next million years, and a 2.5 percent chance Venus will get clipped over the same time frame.
As time goes on – looking 3 million years ahead – the probability of a collision with Earth increases to 11 percent.
Mars got off scot-free in all the test runs with no impacts, and only in one simulation did the Tesla collide with the Sun – sometime within the next 3 million years.
It’s worth pointing out that these calculations haven’t yet been peer-reviewed by other scientists, but as the researchers themselves freely acknowledge, there’s a great deal of mathematical unknowns in these orbital scenarios.
But given the Roadster is estimated to have a virtually immortal half-life of some 20 million years (as it ever-so-slowly erodes into nothingness in space), the team ultimately “expect collision probabilities with the Earth to be substantial”, they write in their paper.
In any case, if the worst happens, there’s really no need to be worried. Not now, nor much, much, much later.
“It will either burn up [in the atmosphere] or maybe one component will reach the surface,” Rein told Science.
“There is no risk to health and safety whatsoever.”
The findings are available on the pre-print website arXiv.org.
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