How Earth destroyed the ninth planet

When NASA scientists began to analyze samples from the moon landing in 1960, they discovered something fascinating. The moon rocks the team had brought back resembled the rocks and dust on Earth. In fact, aside from lower water and iron content, the moon’s chemical composition was almost identical to the Earth’s. This was huge.

In case this does not seem significant, let’s get some perspective on the matter. The moon is without a doubt the most studied astronomical body in history, but by the end of the nineteenth century, scientists still had no idea how it got there. Theories had ranged from the plausible (the Earth and the moon formed together) to the farfetched (the Earth used to have a really big atmosphere and was able to capture a rogue, pre-formed moon), but further scrutiny uncovered holes in them all. By 1900, the predominant though mathematically questionable explanation involved centrifugal force from a fast-spinning Earth throwing off material that coalesced into the satellite.

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You are made of beautiful stardust

Stars Space Outer Beautiful Pictures Secrets Colorful Large Magellanic Cloud Star Forming Stellar Nursery Weekly Show Beautiful

Stars. They are such stuff as dreams are made on. They shine in the night sky, reminders of our insignificance and the vastness of the universe. They may sit millions of light years away, but they are closer than you think.

Simply put, stars are massive balls of plasma held together by their own gravity. Once a critical mass of interstellar dust and debris and accumulates, its gravity pulls it together, heating its core enough to fuse hydrogen into helium. The heat from these reactions balances the gravitational force of the outer shells, preventing the star from collapsing under its own mass. Stars spend most of their lives on what is called the main sequence, fusing hydrogen into helium as they orbit galactic centers at incredible speed.

Stars Space Outer Beautiful Pictures Secrets Colorful Large Magellanic Cloud Star Forming Stellar Nursery Weekly Show Beautiful

Part of a stellar nursery in the Large Magellanic Cloud. Here interstellar debris and supernova remnants come together to form new stars and planets. (Photo: ESA/Hubble)

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How to look back in time (actually)

Back Future Doc Delorean Time Travel Stars Past Weekly Show

Time travel. The idea has captivated humans for millennia. Ancient myths and science fiction imagine rips in the universe, portals that let us observe history before our eyes. What most people do not realize, though, is that they do this every day.

Back Future Doc Delorean Time Travel Stars Past Weekly Show

“We’re gonna need a bigger car.”

Let’s step back—four hundred years back. In the mid-seventeenth century, astronomer Ole Romer noticed something strange about Jupiter’s moons. When they came close to Earth, the time between their eclipses was short, but when they moved farther away the time in between them was longer. Many scientists at the time believed light traveled instantaneously, that our eyes observed Jupiter and its moons in real time. This meant that the moons’ orbits changed depending on their position relative to Earth. It also made no sense.

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