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Bryan Cranston
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Liv Boeree
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Chris Hadfield
Retired Canadian Astronaut & Author
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WATCH: Dinosaurs traveled other parts of Milky Way than humans

Dinosaurs never left Earth, but they still traveled millions of miles through the Milky Way galaxy.

Dr. Jessie Christiansen
  • A new video shows how life has evolved on Earth during the planet's most recent revolution around the Milky Way, also known as one galactic year.
  • A galactic year is about 220 million years, and it was the beginning of the Jurassic period the last time Earth was at this point in its revolution.
  • How will Earth look on its next galactic birthday? It's impossible to know for sure, but a few events seem inevitable.


It's been 200 million years since the dawn of the Jurassic period, the second of the three epochs in the Mesozoic era, during which dinosaurs roamed the Earth. But in terms of how many galactic years have passed since then, the count is just one.

Just as the Earth orbits the Sun, our solar system revolves around a supermassive black hole at the center of the Milky Way galaxy. To complete one revolution takes about 220 million years. So, if you were to look back to when Earth was at this exact point in its previous revolution, you wouldn't see humans. Or any primates. Instead, you might see reptilian pterosaurs flying in the skies, plesiosaurs swimming in the oceans, and massive, razor-clawed theropods walking the land, among other ancient animals that no longer exist today.

To give perspective to the sheer magnitude of Earth's galactic year, NASA research scientist Dr. Jessie Christiansen made a video mapping the evolution of life to Earth's most recent revolution around the Milky Way.

Interestingly, the Jurassic period only took place on one side of the Milky Way, and when Earth was last on the opposite side of the galaxy, it was the mid-Cretaceous period. If you imagine progress of a galactic year as one hour on a clock, the time during which humans have existed on Earth would represent much less than one minute. And that's just for the most recent galactic year.

To get a sense of the physical scale at which this process occurs, check out this video from the American Museum of Natural History.

The Milky Way in future galactic years

Christiansen ends her video by asking what Earth will be like on its next Galactic birthday. It's difficult for scientists to know for sure, but a couple likely changes include: each day will be an hour longer, due to a slowing of the Earth's rotation, and the continents will have merged, making our modern map of the world virtually unrecognizable.

On the cosmic scale, making predictions becomes even more difficult. But based on the available data, a few events seem inevitable:

  • 12 galactic years: No life exists on Earth, and from a distance the planet will likely show no signs that it ever supported life.
  • 15 galactic years: The conditions on Earth are similar to those on Venus.
  • 22 galactic years: The Milky Way and Andromeda Galaxy begin to collide.
  • 500 galactic years: The universe has expanded so much that all galaxies beyond the Local Group have disappeared beyond the cosmic light horizon.

Neom, Saudi Arabia's $500 billion megacity, reaches its next phase

Construction of the $500 billion dollar tech city-state of the future is moving ahead.

Credit: Neom
Technology & Innovation
  • The futuristic megacity Neom is being built in Saudi Arabia.
  • The city will be fully automated, leading in health, education and quality of life.
  • It will feature an artificial moon, cloud seeding, robotic gladiators and flying taxis.
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Childhood sleeping problems may signal mental disorders later in life

Chronic irregular sleep in children was associated with psychotic experiences in adolescence, according to a recent study out of the University of Birmingham's School of Psychology.

A girl and her mother take an afternoon nap in bed.

Personal Growth
  • We spend 40 percent of our childhoods asleep, a time for cognitive growth and development.
  • A recent study found an association between irregular sleep patterns in childhood and either psychotic experiences or borderline personality disorder during teenage years.
  • The researchers hope their findings can help identify at-risk youth to improve early intervention.
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    Why do people believe in conspiracy theories?

    Are we genetically inclined for superstition or just fearful of the truth?

    Videos
    • From secret societies to faked moon landings, one thing that humanity seems to have an endless supply of is conspiracy theories. In this compilation, physicist Michio Kaku, science communicator Bill Nye, psychologist Sarah Rose Cavanagh, skeptic Michael Shermer, and actor and playwright John Cameron Mitchell consider the nature of truth and why some groups believe the things they do.
    • "I think there's a gene for superstition, a gene for hearsay, a gene for magic, a gene for magical thinking," argues Kaku. The theoretical physicist says that science goes against "natural thinking," and that the superstition gene persists because, one out of ten times, it actually worked and saved us.
    • Other theories shared include the idea of cognitive dissonance, the dangerous power of fear to inhibit critical thinking, and Hollywood's romanticization of conspiracies. Because conspiracy theories are so diverse and multifaceted, combating them has not been an easy task for science.

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