Planck Collaboration (2020)
Precision cosmology and the age of the universe.
Open sourceOrigin 01
13.8 billion years ago
The universe opens in impossible heat.
Space expands. Heat rules. Nothing looks familiar yet.
This is not debris flying into emptiness. The emptiness itself begins stretching.
101 noteThe Big Bang is the start of the hot expanding universe.
Scale all of space
State hot and dense
Anchor Planck
Origin 02
380,000 years later
The fog clears. Light gets loose.
Atoms form. The universe becomes transparent enough to shine freely.
That ancient glow still exists today as the cosmic microwave background, the oldest light we can observe.
101 noteBefore this, light kept bouncing inside a dense plasma fog.
Shift plasma -> atoms
Signal CMB
Why care first clear snapshot
Origin 03
Roughly 100 to 250 million years in
Darkness learns how to burn.
Gravity pulls gas into the first stars. Chemistry finally gets interesting.
The Big Bang made mostly hydrogen and helium. Stars had to forge the heavier stuff: carbon, oxygen, silicon, iron.
101 noteNo early stars means no rocky planets later.
Fuel hydrogen and helium
Result first heavy elements
Theme gravity ignites structure
Origin 04
About 4.567 billion years ago
One cold cloud becomes our address.
A rotating pocket of gas and dust collapses inward. The center heads toward a Sun.
This is the leading picture for our solar system's birth: the solar nebula model.
101 noteCloud -> spin -> flatten. That is the basic move.
Framework solar nebula
Motion collapse + rotation
Outcome star and disk
Origin 05
Around 4.56 billion years ago
A star lights. A disk spins flat.
The young Sun brightens at the center while dust and ice circle in bands, rings, and traffic jams.
This disk is the workshop. Without it, there is nowhere for planets to assemble.
101 noteReal young disks show rings and gaps, not smooth blank circles.
Center protosun
Workshop disk
Time limit a few million years
Origin 06
Within roughly 1 to 10 million years
Dust starts keeping score.
Grains become pebbles. Pebbles become planetesimals. Some survive long enough to become worlds.
Rocky planets grow inside. Giant-planet cores grow fast outside, where more solid material is available.
101 noteToday the main model is core accretion. Pebble accretion helps it happen fast enough.
Main model core accretion
Speed boost pebble accretion
Clock gas disk disappears fast
Origin 07
Tens of millions of years later
Then the finished system changes its mind.
Giant planets migrate. Mars stays oddly small. A giant impact likely gives Earth its Moon.
The solar system we see now is probably not the exact layout it had on day one.
101 noteFormation is not one clean build. It is build, collide, move, settle.
Outer story Nice model
Inner story Grand Tack
Moon giant impact
Science Behind The Spectacle
Short story. Real science.
This version is deliberately lighter on words. The science underneath is not lightweight.
The broad arc here follows the leading modern picture: hot early universe, first light, first stars, solar nebula, protoplanetary disk, accretion, migration.
Connelly et al. (2012)
CAIs give the solar system its earliest hard timestamp: 4567.30 +/- 0.16 million years.
Open sourceAndrews et al. / DSHARP (2018)
High-resolution evidence that planet-forming disks are full of structure.
Open sourcePollack et al. (1996)
The classic core-accretion path for giant-planet growth.
Open sourceLambrechts and Johansen (2012)
Pebble accretion as a major speed-up mechanism for giant-planet cores.
Open sourceTsiganis et al. (2005), Walsh et al. (2011), Canup and Asphaug (2001)
Migration and giant-impact models for the final solar-system architecture.
Nice Grand Tack Moon