Why are so many objects in space shaped like discs?

It's one of the most consistent patterns in the unviverse. What causes it?

  • Spinning discs are everywhere – just look at our solar system, the rings of Saturn, and all the spiral galaxies in the universe.
  • Spinning discs are the result of two things: The force of gravity and a phenomenon in physics called the conservation of angular momentum.
  • Gravity brings matter together; the closer the matter gets, the more it accelerates – much like an ice skater who spins faster and faster the closer their arms get to their body. Then, this spinning cloud collapses due to up and down and diagonal collisions that cancel each other out until the only motion they have in common is the spin – and voila: A flat disc.

Apparently even NASA is wrong about which planet is closest to Earth

Three scientists publish a paper proving that Mercury, not Venus, is the closest planet to Earth.

  • Earth is the third planet from the Sun, so our closest neighbor must be planet two or four, right?
  • Wrong! Neither Venus nor Mars is the right answer.
  • Three scientists ran the numbers. In this YouTube video, one of them explains why our nearest neighbor is... Mercury!
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Mining the Moon

How can we use the resources that are already on the Moon to make human exploration of the satellite as economical as possible?

The All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE), a prototype heavy-lift utility vehicle to support future human exploration of extraterrestrial surfaces, at right, is parked beside the Habitat Demonstration Unit - Pressurized Excursion Module (HDU-PEM), at left, a concept off-Earth living and work quarters for astronauts stationed on asteroids, the moon or Mars, 15 September 2010. Photo by: ROBYN BECK/AFP/Getty Images

If you were transported to the Moon this very instant, you would surely and rapidly die. That's because there's no atmosphere, the surface temperature varies from a roasting 130 degrees Celsius (266 F) to a bone-chilling minus 170 C (minus 274 F). If the lack of air or horrific heat or cold don't kill you then micrometeorite bombardment or solar radiation will. By all accounts, the Moon is not a hospitable place to be.

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The moon is inside Earth's atmosphere, European researchers say

Scientists examined data from 20 years ago to reach a startling new conclusion.

Earth appears over the Lunar horizon. Photo taken during the Apollo 11 mission. 1969. Credit: NASA
  • Observations made by the SOHO spacecraft over 20 years ago lead to a new discovery.
  • The Earth has hydrogen envelope as part of its outer atmosphere called the geocorona.
  • The geocorona stretches well past the moon, reveals a study.
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What was Planet V?

About 3.8 billion years ago, the inner planets were bombarded with a cataclysm of asteroids. Could Planet V have been the cause?

TIM BERTELINK via Wikimedia Commons
  • The Late Heavy Bombardment (LHB) occurred about 3.8 billion years ago, during which time Earth, Venus, Mercury, and Mars were assaulted by asteroids.
  • Scientists are pretty sure the LHB occurred, but they're not certain what caused it.
  • It could be that a hypothetical fifth inner planet once existed in our solar system. As it left, it may have caused the LHB.
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