Fast Times in the Early Solar System

Early solar system
An artist’s depiction of the early solar system. In the inset, small particles stick together to form larger particles.
Image credit: NASA/JPL-Caltech/Jangmi Han

Calcium-aluminum-rich inclusions, CAIs, are light-colored masses in carbonaceous chondrite meteorites — they are the first formed solids in the solar system. Being so old, they provide a unique view into processes early in our solar system, including when and how its dust coagulated to form larger objects (like CAIs) and eventually planets. A team of scientists, led by M. C. Liu of the University of California Los Angeles, determined the ages of some microscopic CAIs from a pristine carbonaceous chondrite to peer back into the early days of our solar system and everything in it. Using a precise radio-isotope chronometer, they found that dust grains stuck to each other to form CAIs on (astronomically) short timescales of 50,000 to 100,000 years. This suggests that dust coagulates very rapidly. Their results are further evidence that it didn’t take long for solids to stick together and settle out of the cloud of hot debris surrounding our sun, the very first step toward forming asteroids and planets. READ MORE