Science 3 min read

Dinosaur Earth was on the Other Side of the Galaxy

janez volmajer /

janez volmajer /

Dinosaur Earth was very different from today in many respects.

Very long before Homo sapiens emerged, dinosaurs reigned supreme on Earth for hundreds of million years.

While we’ve been around for only about 315,000 years, give or take, dinos roamed prehistoric Earth between about 245 and 66 million years ago.

Aside from reminding us of our fragility as a species, dinosaurs can also teach us about Earth and the solar system from an astronomical time angle.

A NASA scientist created an animation that tracks the history of dinosaurs in comparison to the movement of the Sun through the Milky Way.

Galactic Whereabouts of Dinosaur Earth

The longevity of dinosaurs was such that Earth had ample time to make a long cross-galaxy journey.

The Moon orbits Earth, and both orbit the Sun. In its turn, the Sun orbits the center of the Milky Way.

The Milky Way’s core is home to Sagittarius A* (pictured here) and many other supermassive black holes. That could explain the rotation of the billions of stars within the galaxy.

But, does the Milky Way orbit “something”? That’s a question for another day. For now, let’s focus on dinosaur Earth.

It takes the Sun roughly 250 million years to complete its rotation around the galaxy’s center with an average orbital speed of around 200 km/s (720,000 km/h or 450,000 mph).

The last time Earth was at its current location in the galaxy, the Age of Dinosaurs was in full swing.


Jessie Christiansen is an astrophysicist at the NASA Exoplanet Science Institute (NExScI). As a leader of a stargazing party, Christiansen explained to the attendees that the solar system was across the galaxy when dinosaurs existed.

She noticed the astonishment of the audience at the mention of this fact. That’s how she got the idea to illustrate the history of dinosaur Earth.

“That was the first time I realized that those time scales — archaeological, fossil-record time scales and astronomical time scales — actually kind of match along together,” Christiansen told Business Insider. “Then I had this idea that I could map out dinosaur evolution through the galaxy’s rotation.”

Christiansen said she made the video using timed animations in PowerPoint in a couple of hours. She noted some slip-ups in the text of the video, like Earth takes 250 million years, not 200 million years, to complete an orbit.

In reality, however, the movement of galaxies and bodies within is much more complicated than what the animation may suggest.

Earth didn’t return to its exact location of 250 million years ago because the Milky Way itself is moving. In fact, our galaxy is on a collision course with the Andromeda galaxy.

“The animation kind of makes it seem like we’ve come back to the same spot, but in reality, the whole galaxy has moved a very long way,” Christiansen said. “It’s more like we’re doing a spiral through space. As the whole galaxy’s moving and we’re rotating around the center, it kind of creates this spiral.”

Read More: Last Day of Dinosaurs Explained in Graphic Details

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Zayan Guedim

Trilingual poet, investigative journalist, and novelist. Zed loves tackling the big existential questions and all-things quantum.

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