Ask a Rocket Scientist: My dog and falling stars

Did you see that fireball last Friday?

Dr. Jeff

I was walking my dog just after sunset, and I saw a nice fireball from the Perseid Meteor Shower.  It was a bright, small ball that streaked about 20 degrees across the sky toward the west from where I was standing.  With the illumination from the sunset, I could see a nice smoke trail.

Perseid Meteor - Courtesy of NASA

This event marked the vaporization of a little piece of rock (less than an inch in diameter) that was once part of Comet Swift-Tuttle.  The comet itself has been orbiting the Sun since the early days of the solar system when it coalesced from material lying around since the formation of the universe that gravity stirred up and mixed in with material that a nearby supernova "barfed" out.

The supernova, which probably happened about 4-5 billion years ago, provided the elements in the rock like silicon, oxygen and iron.  The majority of the hydrogen in the rock came from the formation of the universe 13.7 billion years ago (give or take 160 million years), so I was really witnessing the death of something that had quite a perspective on the history of the universe.

Of course, death is relative.

The atoms themselves didn't die.  They fell to the Earth as dust, joining the approximately 40 tons of space dust that falls onto our planet every day.  At some point in the next 7-8 billion years that space dust, along with the rest of the Earth, will vaporize, or at least become very hot, when the Sun expands into its red giant phase.  The sun is not heavy enough to go supernova, so the universe won't recycle us in quite the same way we formed.  We will instead become part of a pretty planetary nebula that an extraterrestrial astronomer might view.

But then I was done walking my dog.

(Editor's Note: Dr. Jeff Morgenthaler is an astrophysicist conducting research on the solar system from his office in Fort Kent.)