El Gordo Is The Biggest Galaxy Cluster Ever Seen In The Early Universe

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El Gordo Is The Biggest Galaxy Cluster Ever Seen In The Early Universe

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.

Stellar Explosions Can Create The Awesome Beauty Of Light Echoes

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Stellar Explosions Can Create The Awesome Beauty Of Light Echoes

In 2002, the Hubble Space telescope watched as the star V838 Monocerotis exploded in a fiery detonation 600,000 times brighter than our sun. Over four years, the telescope kept watching, and it captured something amazing: instead of gradually petering out, the explosion periodically brightened in what's known as a "light echo."

A Thorne-Żytkow Object Is A Star Within A Star

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A Thorne-Żytkow Object Is A Star Within A Star

There's some weird stuff in the universe. Among all the binary systems, stellar voids, and bubble-shaped nebulae that we know exist, there are a great many we only think exist. One of those is a Thorne-Żytkow object (TZO), or a star that contains another star. At least, that was the case until astronomers finally detected their first TZO in 2014.

The Doppler Effect Tells You A Siren Is Passing And The Universe Is Expanding

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The Doppler Effect Tells You A Siren Is Passing And The Universe Is Expanding

You're probably familiar with the sound of a siren (or a car horn, or a rumbling semi truck) as it approaches and then passes you. The sound starts low and quiet, then begins to rise in pitch as it gets closer, then gradually drops in pitch as it passes and moves down the road. This change in pitch is known as the Doppler effect, and it may surprise you to learn that it's the same phenomenon that tells astronomers our universe is expanding.

Dragonfly 44 Is The Milky Way's "Dark Twin" And Is 99.99% Dark Matter

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Dragonfly 44 Is The Milky Way's "Dark Twin" And Is 99.99% Dark Matter

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.