Comets are fascinating phenomena – they’re often difficult to discern with the naked eye without proper equipment and have dictated great battles, harvests, famines and other worldly events throughout our history.
Halley’s Comet is one of our most famous comets due to its reoccurrence every 75 years or so, one of the few blockbuster celestial events that can happen twice in a human lifetime.
So what makes this latest comet so special?… It could be argued the window of time is just right where we get to share something between us and our ancestors from 50,000 years ago. Not Galileo, not Caesar, not Napoleon…. us. We get to share this window into the past of being able to observe the same celestial body as our distant ancestors.
Meteorologist Anna Hamelin breaks down the finer details of our upcoming comet:
“Comet 2022 E3 (ZTF) is approaching us, and they’re often green. Fortunately, it can be explained by the fact that comets have atmospheres too, so I think I’m qualified to elaborate!
As comets approach the sun, they get warmer and start to melt. The ultraviolet light from the sun also starts breaking apart pieces and even molecules of the comet.
The sun’s UV light can ionize some of the molecules in/around the comet, breaking them off and creating a tail that’s blue in color. The white tail is made of the ice and dust particles that are breaking off the comet as it warms and moves.
Only the actual body and atmosphere of the comet is green though, not the tail. Hang on to your hats and telescopes, we’re about to get really science-y.
One of the atoms prevalent in comet molecules is carbon. The sun’s UV rays can break those molecules apart, sometimes creating dicarbon (two carbons stuck together).
Carbons are NOT a fan of being together though, they’re strong, independent atoms and very unstable in pairs. Dicarbon absorbs some energy from the sun in an effort to stabilize, but goes a bit overboard (and actually just ends up even more unstable), and then starts to decay. In the decay process, dicarbon emits a photon that appears green to our eyes!
However, unlike the ions and dust that form the blue and white tails, dicarbon only lasts for about 2 days. That means it stays “close” to the comet itself, while the ion and dust tails can last for millions of miles.”
E3 (ZTF) will likely not be the biggest or brightest comet humans will see in the near future – but we can recognize the inferred meaning of this glowing trail across the sky. So as we approach late January and early February… go out and see if you can get a peak at our celestial neighbor – and think about how far we’ve come in 50,000 years.