Currently In a Danger Zone? –“The Solar System Has Completed 20–25 Orbits of the Milky Way Since Origin of Humans”

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Our orbit through the Milky Way is not a perfect circle or an ellipse, since the galaxy itself is a landscape of undulating concentrations of mass and complex gravitational fields. As Caleb Scharf observes in The Copernicus Complex, "none of the components of the galaxy are stationary; they, too, are orbiting and drifting in a three-dimensional ballet. The result is that our solar system, like billions of others, must inevitably encounter patches of interstellar space containing the thicker molecular gases and microscopic dust grains of nebulae. It takes tens of thousands to hundreds of thousands of years to pass through one of these regions.

The Solar System is thought to have completed about 20–25 orbits during its lifetime or 0.0008 orbits since the origin of humans. When the last white embers of our Sun die out billions of years from now, we will have completed approximately 60 orbits of our home galaxy.



In fact, our Sun's orbit has only happened 20.4 times since the Sun itself formed 4.6 billion years ago. It’s estimated that the Sun will continue fusing hydrogen for another 7 billion years. In other words, it only has another 31 orbits it can make before it runs out of fuel.

Is there a genocidal countdown built into the motion of our solar system? Research at Cardiff University suggests that our system's orbit through the Milky Way encounters regular speedbumps – and by "speedbumps," we mean "potentially extinction-causing asteroids."

In 1999 astronomers focusing on a star at the center of the Milky Way, measured precisely how long it takes the sun to complete one orbit (a galactic year) of our home galaxy: 226 million years. The last time the sun was at that exact spot of its galactic orbit, dinosaurs ruled the Earth.

"This may happen only once every few hundred million years," Scharf adds, "but if modern human civilization had kicked off during such an episode, we would have barely seen more than the nearest stars— certainly not the rest of our galaxy or the cosmos beyond. But could our planetary circumstances have been that different and still produced us? Would more changeable orbits in a planetary system, or bad weather, or passage through interstellar clouds, also thwart the emergence of life in some way?"

Phenomena such as these could be bad news, causing hostile surface environments on a planet. So it’s a possibility that the planetary requirements for forming sentient life like us will necessarily always present the senses and minds of such creatures with a specific cosmic tableau, a common window onto the universe."

If future research confirms a Milky Way galaxy-biodiversity link, it would force scientists to broaden their ideas about what can influence life on Earth. "Maybe it's not just the climate and the tectonic events on Earth," says UK paleontologist Bruce Lieberman. "Maybe we have to start thinking more about the extraterrestrial environment as well."

The surge in cosmic-ray exposure could have both a direct and indirect effect on Earth's organisms, said Lieberman. The radiation could lead to higher rates of genetic mutations in organisms or interfere with their ability to repair DNA damage, potentially leading to diseases like cancer.

The Daily Galaxy via The Copernicus Complex, Cardiff University, and

Image credit: Top of Page with thanks to Crystal Links




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