TL;DR: planetesimals are mountain-sized rocks (sometimes with ice) that grow from clumps of drifting dust (“pebbles”). The two types of meteorites come from planetesimals that formed in different parts of the Solar System and remained separate. … More From dust to planetesimals
The TL;DR version of this post: the Sun formed in a cluster of about 1000 stars. The Sun’s gas-dominated disk disappeared in a few million years, about the same timescale as the cluster’s dispersal. … More The Sun’s birth cluster and planet-forming disk
This blog series will discuss what we know (and don’t know) about the formation and evolution of our Solar System. … More The Solar System’s story
Just like a doofus with the remote control bouncing between two TV shows, planets can bounce between stars in a binary system… … More Star-hoppers: planets bouncing between binary stars
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!
Here’s something brand new – we made a big splash!
A pile of free-floaters just dropped with a crash!
A hundred new rogue planets! Yup, we just found ‘em
They orbit among stars instead of around ‘em. … More A flock of free-floaters
If too many rocks hit a planet by chance
It breaks up the system’s whole resonant dance! … More Bombardment of 7 orbs
The time capsule must serve as a beacon. Any other civilization that detects it should immediately suspect that it is of artificial origin. And it needs to survive for countless billions of years. … More A cosmic time capsule
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!)
Just one stretched-out orbit takes up lots of space
Can’t add any planets, there just isn’t space
Now, circles are best. And trust me, I’ve tried
Eight or ten orbits fit nicely inside. … More We’re in the cosmic 1%