A few days ago, on the night of Sunday, November 10, residents of East Central Missouri were both concerned and awed as the night sky turned an eerie unnatural green and a large explosion rumbled through the quiet.
This was actually part of a routine meteor shower system active every year from late October to early December. That particular night was the peak of the storm system known as the Northern Taurids. The Northern Taurids are debris originating from the parent object known as 2P/Encke or Encke’s Comet.
What is Encke’s Comet?
Encke’s Comet, named after Johannes Franz Encke, has one of the shortest known orbits in comet and asteroid history. This amazing rock travels past Earth every 3.3 years. It doesn’t even make it as far out as Jupiter. This year, 2019, was Comet Encke’s 64th recorded journey passed Earth, no doubt it has passed many more times than that. There are several reasons why this SHOULD be the most famous comet there is. For starters, Encke’s Comet was the key to scientists understanding what comets are and how they work.
For centuries humanity believed that “shooting stars” were omens of bad and that these objects were short-lived miracles that were only ever seen once and then disappeared. Encke’s Comet was the second comet ever to be identified as periodical (meaning it had a pattern that periodically came full circle). Thus the designation “2P” (“1P” belonging to the Mark Twain famous Hayley’s Comet that comes around every 76 years.)
In 1786, Pierre Méchain’s observation of Comet Encke was the first of such observations to be officially recognized by science. This happened because Johann Franz Encke later used Méchain’s observation as the first observation in a series, in which he proved through extensive calculations that there was a link between observations of comets in 1786, 1795, 1805 and 1818, showing that in fact all of these differently designated objects were in fact one comet returning at a predictable interval. In 1819, Encke published these conclusions in the early journal Correspondance Astronomique, wherein he correctly predicted the comet’s return in 1822.
The predicted return of Encke’s Comet was verified to be accurate by Carl Ludwig Christian Rumker on June 8, 1822. A great step forward for science! Encke also studied the orbital decay of the comet, noticing that it decayed 2.5 hours at each return by the sun. The cause of orbital decay is not precisely known but it is generally believed to correlate to matter from the comet boiling and evaporating off the surface, causing a difference in the size and volume of the object as well as an external force pushing against the comet according to Newton’s Third Law of Equal and Opposite Reaction.
How The Comet Effected Us
So every year as Encke’s Comet passes our orbital zone, just ahead of us, it leaves a wake of debris behind it which Earth then passes through. This debris is known as a meteor shower due to the fact that much of the debris gets pulled into our gravitational field and then shoots through our atmosphere, often falling to Earth or exploding in our atmosphere. Reports vary as to how many pieces of meteorite actually ended up landing in the Midwest but it seems at the moment that approximately four fragments impacted, though it is uncertain if any of them have been recovered for study.
Why a Green Sky?
Why did the sky glow green? Meteors and asteroids are often made from materials and elements not found on Earth. As foreign, or a̳l̳i̳e̳n̳, matter they react with the native gasses and molecules as the heat up during atmospheric entry. This creates colorful vapor displays. What are the waste gasses made of and how do they affect us? We may never totally know, or we may never be told. Up to this point it is safe to assume that they do not have a major impact on our health. The biggest concern would be if a large enough chunk impacted and caused extinction-level fires, earthquakes, climate change and environmental stress. Until that day, sit back and enjoy the show.