El Gordo Is The Biggest Galaxy Cluster Ever Seen In The Early Universe
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The El Gordo galaxy cluster is big. How big is it? It's so big that it would take 3,000 Milky Way galaxies to equal its mass. It's so big that it weighs as much as 3 quadrillion suns. It's so big that a 2012 estimate said it was massive, and then a 2014 estimate said no, it's nearly twice that massive.
Dragonfly 44 Is The Milky Way's "Dark Twin" And Is 99.99% Dark Matter
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In 2015, scientists detected a strange galaxy just about the same size as the Milky Way. Dragonfly 44 is known as the "dark twin" of the Milky Way because it is made up of 99.99% dark matter. Dark matter is... well, no one quite knows what it is. The best understanding we have is that it's an invisible substance that makes up 80% of mass in the universe. Scientists know that dark matter exists because they can see the effects of it in gravity and on the weight of galaxies. Only one-hundredth of one percent of the Dragonfly 44 galaxy is visible matter. But by using the Dragonfly Telephoto Array telescope in New Mexico, scientists were able to detect the galaxy in 2015. The array, which has eight telephoto lenses and cameras, was designed to detect things in space too dim to see with other telescopes. When scientists first observed Dragonfly 44, they thought it must not be as large as it is, because it has so few stars, but they ultimately concluded that it must be dark matter holding the dark mysterious galaxy together. Learn more about Dragonfly 44 in the video below.
The Boötes Void Is The Emptiest Place In The Universe
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Astronomy often focuses on where things are—stars, galaxies, clusters—rather than where they aren't. However, sometimes emptiness can teach scientists just as much. A spherical region of space 250 million light years in diameter, the Boötes void (pronounced boo-OH-tees) is the emptiest area of space in the known universe. In all that space, the void contains only 60 galaxies. For comparison, as io9 points out, our own galaxy has around two dozen galactic neighbors in a space of only 3 million light years. Given that the average distance between galaxies everywhere else in the universe is a few million light years, an expanse the size of the Boötes void should contain around 10,000 galaxies. It contains only 0.6% of that number. There are several theories for the void's existence. One is that galaxies have a tendency to gravitate toward each other, leaving areas of empty space behind. But because the universe hasn't been around long enough for this to create a space the size of the Boötes void, another theory takes an opposite approach: perhaps it's the voids, not the galaxies, that are coming together to create a larger void. Of course, no strange astronomical phenomenon would be complete without an alien theory. It could be that the void does contain galaxies, but the stars within them have been blanketed by a Dyson shell used to power a super-advanced civilization. Which theory is the most plausible? Watch the videos below to form your own opinions.
Last Time Earth Was At This Spot in the Galaxy, Dinosaurs Existed
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You're always moving because the earth is always rotating. It's also revolving around the sun, making a complete orbit once a year. Our sun, likewise, revolves around the Milky Way galaxy, taking our entire solar system with it. It takes the sun approximately 225-250 million years to make a full trip around the galaxy, a period known as a "cosmic year." This means that at any given moment, our planet is in roughly the same spot in the Milky Way it was 250 million years ago. Today, that point in history coincides with the Permian-Triassic extinction, the most catastrophic of our planet's five mass extinction events, when 90% of marine species and 70% of land species died out. After the extensive decimation, the Triassic period began, bringing with it Archosaurs, early grasshoppers, and eventually the first mammals, all of which lived on the supercontinent known as Pangaea. In another 250 million years, we'll arrive back at this spot in the Milky Way. Find out more about the movement of the universe in these videos.
Key Facts to Know
As the Earth rotates, the Equator moves the fastest while the poles move the slowest. 1:06
The Milky Way Galaxy is headed toward the Andromeda Galaxy at approximately 405,500 kph (252,000 mph). 2:40
Here's a breakdown of humanity's celestial speed: 3:58
We're All Moving Through Space Toward The Great Attractor
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The Great Attractor remained mysterious to astronomers for decades, as it sits in the Zone of Avoidance. This zone in the sky is obscured by gas and dust from the Milky Way, which makes it hard for telescopes and other technology to view anything in that direction. Scientists had to use x-ray astronomy to finally scope out the space that the Great Attractor occupies. (Until then, we had only known that our galaxy was moving inexplicably towards that area.) They found a supercluster of galaxies that probably constitutes the anomalous mass of the Great Attractor, and have since determined that this supercluster is moving towards another, larger one: the Shapley Supercluster, which boasts the mass of more than 10 million billion suns.
from Universe Today
Key Facts to Know
Our galaxy, and the galaxies around it, are being pulled toward a specific region of space known as the Great Attractor. 0:29
The Norma Cluster is a supercluster of galaxies found in the area of the Great Attractor. 1:46
The Shapley Supercluster is the most massive galaxy cluster within a billion light-years. 2:36