TL;DR: The Moon is thought to have formed in Earth’s last giant impact with a planetary embryo about 100 million years after the start of planet formation. Highly-siderophile elements indicate that ~0.5% of Earth’s mass was accreted after that point. … More The Moon-forming impact and late accretion on the rocky planets
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”)
This is chapter 6 in the Solar System’s story. This is an action-packed, epic chapter in which a lot of pieces of the puzzle are put together in different ways. (It’s my favorite part.) … More Formation of the rocky planets: choose your own adventure!
TL;DR: Most giant planets form in a bottom-up way, by first growing large cores and then piling gas on top. They migrate throughout their formation. Jupiter may have protected Earth from migrating ice giants. … More Growth and migration of the giant planets
TL;DR: Earth- to Neptune-mass planets migrate through the disk — usually inward, and fast. Giant planets carve gaps in the disk (“anti-donuts”) and migrate slowly, usually inward. Things can get crazy when lots of planets migrate together. … More Orbital migration
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”
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 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%
PLANETPLANET 