A new model of the universe suggests there could be as many as 700 quintillion other planets out there, and Earth doesn't look like any of them.This is huge news because it runs contrary to everything we know about our place in the universe. Back in the early 1500s, Nicolaus Copernicus figured out that the Earth wasn't at the center of the solar system. From then on, the more we learned about the universe, the more clear it became that Earth is cosmically insignificant — an idea called the Copernican Principle. The Kepler Space Telescope has found 32 other planets that, like Earth, sit in the habitable zone around their stars. If you extrapolate those numbers to all the stars we know about, there should be between 40 billion and 49 billion other potentially habitable planets in the Milky Way galaxy alone. And the Milky Way is just one of an estimated 100 billion galaxies.
.With so many exoplanets, there's bound to be a few that resemble Earth. But maybe not. This new model suggests that Earth might be an incredibly unique and special place. To figure this out, a team of astronomers took the information we already know about exoplanets and the evolution of the universe and designed a model that simulated the past 13.8 billion years of our universe's existence. Of all the planets that formed inside the model, Earth sticks out like a statistical sore thumb. Most of those quadrillions of planets in the model are inside galaxies much larger than our Milky Way and orbit stars with compositions totally different from our sun. (The research is available on the preprint server arXiv, and it's been submitted for publication in the Astrophysical Journal.) There are some important caveats to this research, though. The model is only based on the exoplanets that we've already discovered, many of which are larger than Earth. (Larger planets are easier to spot from several light-years away.) And the planets that we have discovered are mostly from only one small swath of the universe. Planets might appear vastly different in other areas. Still, the researchers told Scientific American that their model can't be totally off, and while Earth might not be quite a 1-in-700 quintillion planet, it's certainly an unusual place. h/t Discovery My Yahoo - Search narrows for Planet Nine
Paris (AFP) - US astronomers announced last month they may have found a ninth planet beyond Neptune, but conceded they had no idea where on an estimated 10,000-20,000-year orbit it might be. On Tuesday, a French science quartet said they have narrowed the search area. By studying data from NASA's Cassini spacecraft orbiting Saturn, the seventh planet from the Sun, they could exclude two zones, the team wrote in the journal Astronomy and Astrophysics. Their work confirmed that a ninth planet might exist in the far reaches of our Solar System, co-author Jacques Laskar of the Paris Observatory told AFP, "but not just anywhere". Based on mathematical modelling, the French scientists calculated what influence a ninth planet -- travelling along the orbit postulated by the Americans -- would have on the movement of other planets as it passed nearby. They then looked at how the known planets actually behaved. View gallery
Chart showing the zones where astronomers think the ninth planet in the Solar System is most likely … The postulated planet is thought to circle the Sun in a lopsided, highly elongated, oval loop. At its most distant from the Sun, the planet would be too far too away for any effect on other planets to ever be detectable, thus limiting astronomers to a searchable zone representing only about half of the total orbit. Now Laskar and his team have reduced the search area by 50 percent by eliminating two zones in which they say the modelling does not match reality. "We have cut the work in half," he told AFP. Last month, astronomers Konstantin Batygin and Mike Brown predicted the existence of what they dubbed Planet Nine, about 10 times more massive than Earth. Its existence was predicted with mathematical modelling and computer simulations, and was said to exactly explain the strange clumping behaviour of a group of dwarf planets in the Kuiper Belt, a field of icy objects and debris beyond Neptune. Laskar and his team said the search field can be further narrowed if Cassini, due to finish its mission next year, is extended to 2020. Astronomers expect it would take years to find Planet Nine, if it exists at all. It would take a very large telescope to spot the planet at that distance, and with no clear idea of where on its very large orbit it is. Many other planets have been predicted through modelling over the years, mostly wrongly. In one famous case the science was right -- the discovery of Neptune, first predicted from its gravitational pull on Uranus.
When hunting for black holes, astronomers don't usually try for direct observation. Instead, they look for evidence of the effects of a black hole's massive gravity and radiation.
Impossibly dense, deep, and powerful, black holes reveal the limits of physics. Nothing can escape one, not even light.
But even though black holes excite the imagination like few other concepts in science, the truth is that no astronomer has actually seen one.
"There’s really strong evidence for them, and by now every astronomer believes confidently there are black holes," Peter Edmonds, a NASA astrophysicist, told me. "But there’s no direct image."
Any photo you've seen of a dark mass warping spacetime … well, that's just an illustration: Why no astronomer has ever seen a black hole directlyThe biggest problem with trying to detect a black hole is that even the supermassive ones are relatively tiny."The largest one in the sky [is] the black hole in the center of the Milky Way," n astrophysicist at the University of Arizona, writes me in an email. "And taking a picture of it would be equivalent to taking a picture of a DVD on the surface of the moon."What's more, because of their strong gravity, black holes tend to be surrounded by other bright matter that makes it hard to see the object itself.That's why, when hunting for black holes, astronomers don't usually try for direct observation. Instead, they look for evidence of the effects of a black hole's gravity and radiation."We typically measure the orbits of stars and gas that seem to circle around very dark 'spots' in the sky and measure how much mass is there in that dark spot," Psaltis says. "If we know of no other astrophysical object that can be so massive and so dark as what we just measured, we consider this as very strong evidence that a black hole lies there." We do have indirect images of black holes, howeverSome of the best indirect images of black holes come from the Chandra X-ray Observatory, where Edmonds works. "The friction and the high velocities of material forming out of a black hole naturally produces X-rays," he says. And Chandra is a space telescope specially designed to see those X-rays.For example, the Chandra observatory documented these X-ray "burps" emanating from the merger of two galaxies around 26 million light-years away. The astrophysicists suspect that these burps came from a massive black hole: Similarly, the fuchsia blobs on this image are regions of intense X-ray radiation, thought to be black holes that formed when two galaxies (the blue and pink rings) collided: Similarly, here are X-rays and sound waves emanating from the central region of the Perseus galaxy cluster — more indirect evidence of a black hole:
And in this GIF, the Chandra telescope saw the largest X-ray flare coming from the black hole suspected to lie at the center of the Milky Way galaxy.
And here's a zoomed-out image of that X-ray flare.
We can see black holes spew massive jets of matter into the universeThis composite image (combining data from Hubble and a radio telescope) shows jets of energy and matter being thrown out of the center of the Hercules A galaxy. These jets shoot out at nearly the speed of light, demonstrating the awesome destructive power of the objects.
This next image* shows massive jets that arethought to be propelling away from the black hole at the center of Centaurus A, a galaxy 13 millionlight-years away. The jets are longer than the galaxy itself
ESO/WFI (visible); MPIfR/ESO/APEX/A.Weiss et al.
(microwave); NASA/CXC/CfA/R.Kraft et al. (X-ray)
Astronomers have observed stars orbiting mysterious
dark objects, which are most likely black holes
This 16-year time lapse of the stars moving near the
center of the Milky Way galaxy is evidence of a black
Very soon we may see an actual black holeA true image of a black hole would reveal its event horizon. That's the perimeter beyond which nothing can escape. Scientists speculate the event horizon would look like what you see in illustrations: a sudden boundary between bright lights in space and a void.
A true image might also show an accretion disk — a bright ring of matter that swirls around it. (The black hole in the movie Interstellar shows an accretion disk.)What's exciting is that in the next few years, scientists hope to be able to confirm the existence of the black hole in the center of the Milky Way — and determine what it looks like.That's because of the Event Horizon Telescope — a global network of sensors that, in effect, forms a telescope as large as the Earth. It's on track to take a snapshot of the black hole by the end of 2017, and is expected to produce the first image of an event horizon. "What they’re hoping to see is the actual shadow, the actual dark region," Edmonds says. "That will be a big deal."With a direct image of a black hole, scientists will be able to learn more about the effects of extreme gravity, and can further test Einstein's theory of general relativity.