A couple of weeks ago we went out to find Comet NEAT. After some starhopping around in the general direction of where the starmaps said it should be, we found it — looking like a little smudge of light. I know there are folks who would say, “so what?” and then shrug their shoulders as if we were crazy. But, to me that little smudge was fascinating. It was the outward manifestation of a block of dirty ice in orbit around the Sun. That ice is left over from the creation of the solar system, some five billion years ago. And, as it goes around the Sun, it leaves little bits of itself behind in the form of a tail and a sprinkle of particles. Eventually those particles will find their way into our atmosphere as the Earth plows through the cometary wake in its own orbit. We’ll see them as meteors.
Nothing goes to waste in the solar system, or in the universe, for that matter. The comet we see today leaves behind stuff that we see later as meteorites. The Sun puts out a huge stream of particles that flows past the Earth and out into interplanetary space. Eventually it thins out and the “edge” of that stream is, essentially, the “edge” of our solar system. The particles in that stream interact with planetary magnetic fields, and on some worlds (Earth, Jupiter, Saturn, some of the larger moons) we see the interaction as auroral glows.
The solar wind is a form of mass loss that enriches the interstellar medium with elements that eventually get used in a new generation of stars. Some five billion years from now the Sun will swell up to become a red giant, and unleash more of itself to the space between the stars. All that stuff will also become part of the seedbeds for the next stellar families to spring up, complete with stars, planets, asteroids, moons, and comets. Larger stars die in supernova explosions which also recycle stuff into the interstellar medium. That, too, goes into the stellar formation factories of the future. The result? More stars. More worlds, moons, asteroids, and comets. It’s lovely cycle of birth, life, death, and rebirth.
So, next time there’s a comet for us to see, think about this cycle as you spot the lovely shrouded coma and tail that stream out from the comet. It’s part of the life-dance of the universe.