The giant planet instability (the “Nice model”)

TL;DR: The giant planets underwent a dynamical instability that shook up the entire Solar System and likely ejected an extra ice giant. The instability happened early, perhaps triggered by the dispersal of the gaseous planet-forming disk. … More The giant planet instability (the “Nice model”)

From planetesimals to planetary “embryos”

This is chapter 3 in the Solar System’s story. We’re chugging along, growing bigger and bigger things… Planetesimal accretion After mountain-sized (~100 km-scale) planetesimals form from concentrations of drifting pebbles, they continue to grow in two ways. The simplest growth route for planetesimals is simply to crash into other planetesimals; this is called planetesimal accretion. … More From planetesimals to planetary “embryos”

Cosmic fireworks!

Time for an astro-thought experiment. You belong to a super-advanced civilization with the ability to shape the cosmos as you wish. You can move around black holes, stars, planets, comets and moons (like the builders of the ultimate planetary systems). What would your civilization plan for big celebrations? What are their ‘fireworks’? What astronomical phenomena … More Cosmic fireworks!

Cohorts of stars orbiting black holes (with planets, moons, and eclipses!)

This post starts off with some world-building, jumps into eclipses and moons’ orbits, and finishes with a brand new Kalgash system that Isaac Asimov would be proud of (dropped into darkness every 2000 years!). More than one planet can share the same orbit around a star. This is not big news: the concept of Trojan … More Cohorts of stars orbiting black holes (with planets, moons, and eclipses!)

Real-life Sci-Fi World #2: the Hot Eyeball planet

Welcome to Real-life Sci-fi worlds.  We use science to explore life-bearing worlds that are good settings for science fiction.  Up today: the hot Eyeball planet. Planets very close to their stars are too hot for life, right?  Well, not always! Take the Earth and move it closer and closer to the Sun.  It gets hotter … More Real-life Sci-Fi World #2: the Hot Eyeball planet

Something amazing will happen on June 15th but no one on Earth will see it

I discovered something spectacular completely by accident.  I was getting ready for the announcement of the discovery of the extra-solar planet Kepler-186 f.  You remember, the Earth-sized planet in the habitable zone?  It was all over the news (even in French) just a couple months ago. I made an animation of the Kepler-186 system.  The … More Something amazing will happen on June 15th but no one on Earth will see it