How a single star changed our solar system

It doesn’t happen often that change takes place in our solar system. Every object has been around for so long and with everything being so far apart, things just seem to be going their steady, predictable way. Every now and then an asteroid passes Earth and astronomers will talk about a near miss. This February, 2 small asteroids passed Earth really closely. The closest one came up to 64.000 kilometers of Earth, the other was with 184.000 kilometers just as far away as the Moon is. But something much bigger happened a long time ago, although astronomers will consider the event pretty recent.

This star came really close

Approximately 70.000 years ago, a single star approached our solar system. This nomadic star, not part of any constellation, came within a light year of the Sun. In comparison, the nearest star Alpha Centauri A, is 4.2 light years away from us. The star known as Scholz’s star was thought to have passed us peacefully, but now it seems that it might have not been so unnoticed after all. Astronomers believe that it caused quite some mayhem in our solar system.
At the same time that humanity struggled for survival due to a massive volcanic eruption, our own solar system had a rumble with Scholz’s star. This red star cruised just past the Oort cloud. This is a theoretical enormous cloud of millions of icy objects that form the outermost edge of our solar system. Because there are no significant objects in the vicinity, it was believed that the star’s passing had no effect whatsoever. But a research measuring patterns in the distribution of radiants of observed hyperbolic minor bodies proved otherwise.

The orbit of objects in the night's sky

Astronomers started analyzing the orbital evolution of 339 known minor objects such as asteroids and comets with an hyperbolic orbit. This means their orbit will eventually send them out of the solar system. The research indicated that 36 of these objects, so more than 10% of the researched objects, have an orbit that originated from the direction of the Gemini constellation. It can’t be a coincidence that that is the exact spot where objects should be coming from were they influenced by the passing of Scholz’s star 70.000 years ago.
Carlos de la Fuente Marcos, astronomer at the Universidad Complutense de Madrid, explains it as follows: “In principle, one would expect those positions to be evenly distributed in the sky, particularly if these objects come from the Oort Cloud; however, what we find is very different: a statistically significant accumulation of radiants. The pronounced over-density appears projected in the direction of the constellation of Gemini, which fits the close encounter with Scholz’s star.”

So the passing of a star billions of kilometers from our homes can make a huge difference in our night’s sky. And although it happened thousands and thousands of years ago, in astronomy that is like a blink of the eyes, and we see the results of the event even today.

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