Rings, Orbits and Space Storms with Dr. Phil Nicholson

Rings, Orbits and Space Storms with Dr. Phil Nicholson

November 29, 2025 · 47 min · Episode 19

About this episode

Dr. Charles Liu and co-host Allen Liu discuss planetary ring systems and orbital mechanics with Dr. Phil Nicholson.

How do planetary ring systems rings form, and what keeps them in line? What exactly is the Dragon Cloud of Saturn? And what’s up with quasi moon 2025 PN7? To find out, Dr. Charles Liu and co-host Allen Liu welcome Cornell University’s dynamical astronomer Dr. Phil Nicholson for a refresher course in orbital mechanics. As always, though, we start off with the day’s joyfully cool cosmic thing, which is right up Phil’s alley: the recent discovery of quasi moon 2025 PN7. Phil unpacks the orbital mechanics to explain the critical differences between quasi moons and regular moons, and also 2025 PN7’s strange relationship to Earth’s orbit. He also explains the dynamics of the sun’s tidal forces and Earth’s Hill Sphere. For our first question from the audience, Jameson asks, “Are meteorites smaller copies of planets. Are all of them the same?” Rather than discuss meteorites, which are the tiny survivors that have crashed on Earth, Phil pivots to where many of them come from in the first place: asteroids. Really big asteroids share some characteristics with planets, like being spherical in shape, whereas the smaller ones can be highly irregular, like the dumbbell-shaped asteroid 216…

More episodes of The LIUniverse with Dr. Charles Liu

Explore listener stats, chart rankings, contacts and more on the The LIUniverse with Dr. Charles Liu podcast page.