We thought young stars, about 1 million years old, would have larger, brighter discs, and older stars from 10 to 100 million years old would have fainter ones. But we found some young stars missing discs and some old stars with massive discs.

Because this belt has more asteroids than ours, collisions are larger and more frequent, which is why Spitzer could detect the belt. Our present-day solar system is a quieter place, with impacts of the scale that killed the dinosaurs occurring only every 100 million years or so.

We had no idea that Spitzer would ever see light echoes. Sometimes you just trip over the biggest discoveries.

It's a mess out there. We are seeing that planets have a long, rocky road to go down before they become full grown.

I thought that was probably the most energized Earl's been in a while.

No question. I thought he made some great defensive plays.