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A new study by scientists at the Planetary Science Institute (PSI) has revealed a secret: stars passing near the solar system not only decorate the night sky, but also have the power to alter Earth’s orbital fate and, consequently, to shape its climate over the millennia. .
Stars impact our orbit
As we all already know, Earth’s orbit around the Sun is dynamic and subject to variationmainly attributed to the gravitational influence exerted by the gas giants of our solar system, such as Jupiter and Saturn.
However, a new study reveals an additional factor: As the Sun and other stars orbit the center of the Milky Way, stellar encounters occur and cause alterations in planetary orbits.
Stellar Cartography: Passing Stars Altered Orbital Changes For Earth And Other Planets
Illustration of the uncertainty of Earths orbit 56 million years ago due to a potential past passage of the Sun-like star HD7977 2.8 million years ago. Each points distance from the center pic.twitter.com/zjiR4qvhuw
— David Ullrich (@DavidUllrich202) March 26, 2024
These events, although rare on a cosmic level, have a considerable impact on the orbital evolution of the Earthand therefore influence our climate over millions of years.
How can these distant stars influence our climate?
The Planetary Science Institute used advanced simulations to reconstruct Earth’s orbital past. What is the result ?
Each stellar encounter leaves a mark on Earth’s orbit, changing its eccentricity and, therefore, its climate for millions of years.
Remember that the eccentricity of the Earth’s orbit is a crucial factor which determines the shape of the trajectory that the Earth follows around the Sun. This parameter significantly influences the amount of solar radiation our planet receives, as well as the intensity of solar radiation, seasons and long-term climate cycles.
How far from Earth should the star approach?
Although a star’s gravitational influence on Earth and its orbital eccentricity depend on several key factors, such as stellar mass, approach distance, speed and orientation of Earth, generally speaking , it is estimated that a star would have to pass less than 1 light year or 63,241 astronomical units (AU) to have a noticeable effect.
However, even a star passing at a greater distance could have a significant influence if its mass is large enough.
Two events that changed the Earth’s climate
A striking example of this phenomenon is the approach of the star HD 7977 to about 2.8 light years from the Sun, about 2.8 million years ago. This event triggered an abrupt warming, known as the Pliocene thermal maximum, that has confounded scientists for decades.
Thanks to this study, we can now give a clearer explanation: nearby stars have left their mark on the Earth’s orbit, increasing its eccentricity and causing a temperature increase of between 5 and 8ºC.
This beauty is an illustration of Scholz’s star! Nearly 70,000 years ago, it zoomed past the outer edge of our solar system carrying its companion, a likely brown dwarf, along for the ride. Here’s what we know: https://t.co/842PQdV0Gx pic.twitter.com/Fj7wXbFlm9
— NASA (@NASA) February 26, 2019
Another illustrative case is the encounter with Scholz’s star, which is estimated to have passed just 0.8 light years from the Sun around 70,000 years ago. This proximity could have triggered an ice age on Earth, further highlighting the impact that the passage of stars can have on our planet.
News reference:
Kaib, Nathan and Raymond, Sean. (2024). The passage of stars as an important factor in the paleoclimate and orbital evolution of the solar system. Letters from the astrophysical journal. 962. L28. 10.3847/2041-8213/ad24fb.
