From black holes to dark matter, 6 space oddities explained by an expert
When it comes to life's biggest mysteries, understanding exactly what's out there waiting in space is one of the most difficult to decode. From black holes to dark matter, there are still enough things in the universe that scientists can't quite explain that it can make your head spin. For instance, believe it or not, there are still several questions surrounding the way black holes form in the first place. Scientists are still on the fence about whether or not dark matter is a legitimate phenomenon. There’s so much to explore in the vastness of space that it may be lifetimes before we’re able to unlock the secrets behind them. Whether you’re looking to learn more about space anomalies or just want to muse over the oddest things floating around up there these objects will have you raring to learn more about the infiniteness of the universe.
You’ve likely heard of black holes before, as one of the more common space phenomena that scientists discuss. But their familiarity doesn't mean much when they're still very much behemoths that we just don't know a lot about. In a nutshell, a black hole is the result of gravity pulling so hard in a certain area in space that even light has no chance of escaping. Black holes are thought to be the result of matter being squeezed into a space too tiny for it to reasonably occupy, which can occur as aresult of a star's death.
Because light is incapable of escaping black holes they're invisible to the human eye. Researchers must utilize special telescopes and other instruments to locate them in space, despite the fact that they're capable of absolutely massive sizes. The largest black holes thought to exist, of which there is one believed to be at the center of our Milky Way, are known as supermassive black holes. However, scientists still aren't completely sure how those come into being just yet.
"We have a good idea how 'run-of-the-mill' black holes form - during explosions of massive stars called supernovae," Professor Eric Gawiser of the Department of Physics and Astronomy at Rutgers University told Mic.
"We don’t yet know how supermassive black holes form - were there ‘seeds’ from the direct collapse of clouds of gas and dark matter in the early universe? Or perhaps the first generation of stars was much more massive than present-day stars and left behind 100-solar-mass (or larger) black holes? The discovery of gravitational waves by LIGO (Laser Interferometer Gravitational-Wave Observatory) revealed that there are a lot of 20-30 solar mass black holes in our universe."
There are still plenty of unknown factors when it comes to black holes, but one thing is certain: they’re massive, capable of doing serious damage to objects in space around them, and they’re not appropriate for humans (or any beings) to ever approach.
What happens when a star explodes? You might very well get what's called a neutron star.
"Like the 'run-of-the-mill' black holes, neutron stars are formed when massive stars explode," Professor Gawiser told Mic. "If the core of the star that’s left behind is more than about twice the mass of our Sun, it forms a black hole; otherwise, we get a neutron star."
Neutron stars can pack about 1.3 to 2.5 times the mass of our sun into a sphere that's about 12 miles in diameter.
"The compression of the core of the star during the explosion causes protons and electrons to combine into neutrons, which effectively form a single giant atomic nucleus," Gawiser explained of the massive compression. "The neutron stars that result are amazingly dense, packing roughly the mass of our Sun, which is a million times bigger than Earth in volume, into the size of a small city. A single drop of neutron star material has more mass than a skyscraper."
According to NASA, the matter inside a neutron star gets packed so tightly, a simple sugar cube-sized amount would weigh "more than 1 billion tons, about the same as Mount Everest." Yikes.
Cosmic rays are an intriguing phenomenon. They're high-energy protons and nuclei that move through space at the speed of light. They typically originate from our sun and even galaxies outside of our solar system.
"They are Hydrogen nuclei (protons) and even Helium nuclei that arrive from distant space and create showers of energetic particles in our atmosphere," explained Professor Gawiser.
As such, scientists spend time studying cosmic rays to figure out what they're composed of to get to the bottom of where they originated from. Since there's no direct way to analyze where they were made, that's the only option to try and uncover their origin – through indirect means.
"Experiments have found that they can be formed in exploding stars (supernovae) or actively accreting supermassive black holes, and that the most energetic cosmic rays come from outside our Milky Way galaxy and have therefore been traveling at such high energies for millions of years before reaching Earth."
The earliest studies of cosmic rays took place with electroscopes, but scientists later leaned on Geiger-Miller counters and cloud chambers. Now, studies are tackled by way of scintillation counters, which use fluorescent materials that respond with their own light sources when hit by the radiation cosmic rays produce. It isn't a surefire way, of course, but it's one of the most accurate options we currently have to further our studies of the high-energy sources of radiation.
Quasars are extremely bright objects that are sometimes "powered" by black holes. They're described as massive celestial objects that continue to emit astronomical amounts of energy. However, they typically resemble a star when you see them through a telescope. They're also known as the brightest objects in the universe, for good reason. NASA estimates that they're capable of emitting "hundreds or even thousands of times the entire energy output of our galaxy."
Most of the twinkling star-like objects were found billions of light-years away, but since light takes so much time to travel, we're likely seeing quasars the way they were billions of years ago. Quasar 3C 273 was the first quasar to be identified, and it's 2.5 billion light-years from Earth. NASA states that it's also one of the closest quasars to our planet, which drives home how ridiculously bright these stars really are, as they can gleam around 10 to 100,000 times brighter than the entire Milky Way. Interestingly, they're often seen as the result of when a black hole begins to fade out of existenc.
"Quasars are powered by the active accretion of gas onto supermassive black holes," Gawiser explained. "They can be viewed as an inevitable consequence of the existence of those supermassive black holes, and we think that every such black hole undergoes an active (quasar) phase at least once during its lifetime. But that’s incredibly hard to prove - astronomers can only view a given object at one snapshot in its life. We see the brightness of quasars varying on timescales of days to years, but we’ve not yet seen one turn on or off entirely."
Exoplanets are simple to explain in theory, but they're still quite confounding. In our solar system, all planets orbit around the Sun. Any planets found throughout the solar system revolving around stars that aren't our sun are called exoplanets. Typically, however, these exoplanets are hidden behind the lights of the stars they're orbiting around, just like Earth and its brethren in the solar system.
According to NASA, this affects the way scientists can detect and study exoplanets, and they instead inspect the effects said planets have on the stars around them. Stars found around exoplanets travel on an off-center path, and can appear as though they're "wobbly." A large number of planets have been discovered by scientists while sizing up possible "wobbly" orbits, but this method can only be applied to planets the size of Jupiter or larger. In fact, even Earth-sized planets are difficult to find because their "wobbles" are much smaller and harder to see in the first place.
“Before planets orbiting other stars were discovered (which led to 2/3 of the most recent Physics Nobel Prize), we had solid theories of how to form planetary systems that look like ours - planets in nearly circular orbits with rocky planets close to the star and gas giants/ice giants far from the star,” he explained of exoplanets’ formation. “Those theories turned out to be rubbish, as most planetary systems we now know about look very different from ours, with ‘hot Jupiters’ commonly found close to the star and lots of highly elliptical orbits. So in a sense, we are the odd happening in space! And we’re very lucky about that, because the small fraction of potentially habitable exoplanets are typically found in the small fraction of systems that do look like ours.”
Dark matter is a bit of a difficult concept to wrap your head around. Essentially, when stars first began forming years after the original Big Bang, they slowly gathered into galaxies as we know them now. Galaxies formed out of the stars, and eventually planets began to take shape. All of these types of matter eventually formed "clusters." But the invisible force holding everything together is gravity.
However, when it comes to some space clusters, the space between galaxies is undetectable by telescopes, with scientists opting for X-rays or gamma rays to study them. While investigating, they ended up discovering that there's about five times more mass trapped in the clusters than can be detected by the instruments that we currently have. The name for this "invisible" matter awarded to the mass is "dark matter," coined in the '30s by astronomer Fritz Zwicky.
"We have very strong evidence that there is extra matter in galaxies and clusters of galaxies that is different from the familiar stuff of protons, neutrons, and electrons," Gawiser told Mic. "We call that dark matter, because it has gravity just like any other kind of matter but does not emit light and doesn’t seem to interact with regular matter. Without dark matter, the stars in our Milky Way galaxy would be flying away from each other, because the visible matter (stars and gas) doesn’t have enough gravity to keep them in orbit."
It's a plausible theory, but the problem is that scientists haven't actually discovered dark matter to prove that it actually exists.
"Despite many experimental efforts, we have not yet detected actual particles of dark matter. So we only have theories about what types of particles the dark matter could be made from, and the leading theory should have been confirmed by the Large Hadron Collider at CERN but hasn’t been. So we cannot prove that our dark matter explanation for the extra gravity is right, but we don’t have a better one."
Talk about a mysterious type of matter – it likely exists, but we simply can't prove it at this time. And as Gawiser notes, when you talk about dark matter, you must also discuss dark energy.
“Dark matter is roughly 25% of the total energy (density) in the universe, dark energy is roughly 70%, and the stuff we that we are made of and can actually study in laboratories is only 5%. Dark energy is a theory about what is causing the expansion of the universe to accelerate, and it’s really one of three possibilities," Gawiser said. "The others are a 'cosmological constant' as hypothesized by Einstein (although he later wished he hadn’t invoked it and called it his 'greatest blunder') and the idea that Einstein’s theory of General Relativity is subtly wrong on scales as large as our universe. That latter theory is referred to as 'modified gravity' and would mean that dark energy doesn’t exist after all."
Astoundingly, these are only a small sampling of the strange phenomena out in the universe. Scientists are hard at work researching each item, but it looks like we’re still leagues away from understanding it all. From what we’ve seen so far, there’s always going to be something out there that has our brightest minds scratching their heads – that’s part of the fun, after all.
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