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Astrophysicist Gongjie Li Unravels the Mysteries of Planetary Seasons

Astrophysicist Gongjie Li investigates the causes of planetary seasons, focusing on the effects of axial tilt and 'spin precession' and their impact on Earth and other planets.

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Dil Bar Irshad
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Astrophysicist Gongjie Li Unravels the Mysteries of Planetary Seasons

In the cosmos, the rhythm of seasons is a dance choreographed by the distinct axial tilt of each planet. The study of these celestial ballets has been the focus of astrophysicist Gongjie Li, an Assistant Professor of Physics at the Georgia Institute of Technology. Funded by NASA, Li's research delves into the reasons behind seasonal patterns, centring on the effects of a planet's axial tilt or obliquity.

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Earths Unique Obliquity: A Seasonal Orchestra

Our home planet, Earth, has an axis tilted about 23 degrees from vertical, a feature that triggers the varying intensity of sunlight across different hemispheres, resulting in the changing seasons we experience. Li articulates that planets ideally aligned axially with their orbit around the sun, assuming a circular orbit, wouldn't bear witness to seasons due to a constant influx of sunlight.

Spin Precession: The Cosmic Wobble

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Beyond the tilt, another element in Earth's climatic equation is 'spin precession'—a wobble in the planet's rotation triggered by gravitational pull. This wobble affects the Earth's climate over extended periods, causing broad climatic shifts such as ice ages or warm periods. Extreme variations in obliquity can trigger erratic seasons, or even 'snowball' conditions, where the entire planet is encased in ice.

The Galactic Neighbours: Planets, Moons and Obliquity

Li's research also explores how other celestial bodies in our solar system influence obliquity variations. Our moon, for instance, serves as a stabilizing factor, preventing extreme wobbles similar to those seen on Mars. The team further investigated the spin axis variations of exoplanets. They focused on Kepler 186f—an Earth-sized planet in a habitable zone—to understand its potential for habitability and whether it could house a moon that could stabilize its obliquity, much like ours.

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