Researchers have made a groundbreaking discovery, revealing that Earth’s orbit, once thought to be constant, has undergone changes over time. The shift in the planet’s path around the Sun is attributed to the influence of other suns that may have passed through the Solar System in ancient history.
Led by Nathan A. Kaib, Senior Scientist at the Planetary Science Institute, the research links changes in Earth’s orbital eccentricity to fluctuations in climate, particularly during episodes of ancient climate anomalies. The study, published in Astrophysical Journal Letters, highlights a significant orbital change around 56 million years ago, coinciding with a temperature rise of 5-8 degrees Celsius.
As the Sun and other stars orbit the Milky Way’s center, they occasionally pass near one another, a phenomenon known as stellar encounters. The team’s simulations, unique in considering such events, demonstrate that a star passes within 50,000 astronomical units (au) of the Sun every 1 million years on average, with a closer approach within 10,000 au occurring every 20 million years on average.
The research also emphasizes the role of Jupiter in Earth’s changing orbital eccentricity. Perturbations caused by giant planets like Jupiter, Saturn, and Uranus influence Earth’s orbit over time. Passing stars initially impact these giant planets, creating a ripple effect that ultimately affects Earth’s orbit.
“Given these results, we have also identified one known recent stellar passage, the Sun-like star HD 7977, which occurred 2.8 million years ago. This passage has the potential to alter simulations’ predictions of Earth’s orbit beyond approximately 50 million years ago,” explained Kaib.
While the vast distance of these passing stars may not significantly impact Earth’s orbit, the findings open new avenues for understanding the intricat
