Meteor showers shed light on where comets formed in the early solar system | Science & Technology

“The meteoroids we see as meteors in the night sky are the size of small pebbles,” said lead author and SETI Institute and NASA Ames meteor astronomer Peter Jenniskens. “They are, in fact, the same size as the pebbles that collapsed into comets during the formation of our solar system.”

As our solar system formed, tiny particles in the disk around the young Sun gradually grew larger until they became the size of small pebbles.

“Once pebbles grow large enough to no longer travel along with the gas, they are destroyed by mutual collisions before they can grow much bigger,” said NASA Ames planetary scientist and co-author Paul Estrada. “Comets and primitive asteroids instead were formed when clouds of these pebbles locally collapsed into kilometer-sized and larger bodies.” /p>

Fast forward 4.5 billion years: when comets approach the Sun today, they crumble into smaller pieces called meteoroids. Those meteoroids co-orbit with the comet for a while and can later create meteor showers when they hit Earth’s atmosphere.

“We hypothesized that comets crumble into the sizes of the pebbles they are made of,” said Jenniskens. “In that case, the size distribution and the physical and chemical properties of young meteoroid streams still contain information about the conditions in the protoplanetary disk during this collapse.”

Jenniskens and his team of professional and amateur astronomers use special low-light video cameras in networks all over the world to track meteors in a NASA-sponsored project called “CAMS” — or Cameras for Allsky Meteor Surveillance (http://cams.seti.org).

“These cameras measure the meteoroids’ paths, how high they are when they first light…