When dinosaurs ruled the Earth, the planet was on the other side of the galaxy.
New animation by NASA scientist Jesse Christiansen shows how long the reign of the dinosaurs lasted and how short the era of humans was when compared to tracking the movement of our solar system along the Milky Way.
Our sun orbits the center of the galaxy, completing its rotation every 250 million years. So the Christiansen animation shows that the last time our solar system was at its current point in the galaxy, the Triassic period was in full swing and dinosaurs were just beginning to emerge. Many of the most iconic dinosaurs were orbiting the Earth when the planet was in a completely different part of the Milky Way.
Christiansen got the idea to illustrate this story when she was running a star party at the California Institute of Technology in Pasadena. The attendees were amazed when she mentioned that our solar system was across the galaxy when dinosaurs roamed.
"This was the first time I found out that those time scales ̵
The resulting video puts both deadlines in perspective:
—Dr. Jesse Christiansen (@aussiastronomer) August 28, 2019
Christianson said it took her about four hours to make the movie, using animations over time, in PowerPoint. She also noted a few minor corrections to the text in her video: the plesiosaurs are not dinosaurs, and we end the galactic orbit every 250 million years (not 200 million years).
"Spiraling through space"
However, galactic movement is more complex than shown in the video. The other stars and planetary systems in the galaxy also move at different speeds and in different orbits. The inner parts rotate faster than the outer regions.
Moreover, the galaxy itself moves through space, slowly approaching the nearby Andromeda galaxy.
"The animation kind of makes it look like we're back in the same place, but in fact the whole galaxy has been going a long way," Christiansen said. "It's more like spiraling through space. As the entire galaxy moves and rotates around the center, it somehow creates that spiral."