Cosmic Origins &
Star Stuff
Star Stuff
The 13.8-billion-year-old event that birthed our universe.
What is the Big Bang?
The process where colliding particles clumped together into larger bodies.
What is accretion?
The steady breakdown of unstable elements into stable ones.
What is radioactive decay?
Along with plate tectonics, this planetary process destroyed Earth's original rocks.
What is the rock cycle?
The circular depression left on a surface by a meteorite strike.
What is an impact crater?
The two light elements formed during the Big Bang that fueled the first stars.
What are hydrogen and helium?
Along with rock, this material made up planetesimals in the hot inner nebula.
What are metals?
Variations of an element with the same proton count but different neutron counts.
What are isotopes?
The accepted age, in billions of years, of Earth and the solar system.
What is 4.54 billion years?
What a high density of craters reveals about a surface's age.
What is older?
Our Sun's generation, built from recycled ancient star material.
What is a third-generation star?
The separation of Earth into layers based on density while molten.
What is differentiation?
The time needed for half of a parent isotope sample to decay.
What is a half-life?
These space rocks, like the Canyon Diablo fragment, yield Earth's best age estimate.
What are meteorites?
The historic rate of impacts across the solar system (constant, fluctuating, or increasing).
What is constant?
The cloud of dust and gas where our solar system began forming.
What is a nebula?
The protoplanet that struck Earth, leading to the Moon's creation.
What is Theia?
The stable isotope produced by the decay of an unstable parent.
What is the daughter isotope?
Rocks retrieved from this body dated back 4.4 to 4.5 billion years.
What is the Moon?
Earth forces—along with plate tectonics—that erase impact craters.
What are weathering and erosion?
This stellar explosion likely triggered the collapse of our solar nebula.
What is a supernova?
The surprisingly short timeframe (in years) it took orbiting debris to accrete into the Moon.
What is 100 years?
The rock type geologists directly test using slow-decaying isotopes.
What are igneous rocks?
Non-absolute technique used alongside igneous dating to age sedimentary rocks.
What is relative dating?
Besides Earth and the Moon, the cratered planet mentioned in the text.
What is Mercury?