February 2023
The Backyard Astronomer
Adam England

Ancient Visitor From the Outer Solar System

It’s even green.

The Upper Paleolithic, an age of human prehistory ranging from 50,000 to 12,000 years ago, brought the first known organized settlements, advancements in tools and weapons, and artistic work. Early petroglyphs (carved or etched) and pictographs (painted) started with simple lines and dots, and soon evolved to include traced hands, animals, people and boats. While we cannot presume to know the full intents of the respective artists, some appear to have been purely artistic, while others seem to relay information on game animals, locations, even seasons and the passage of time. Lunar cycles, constellations and unique astronomical events have been documented on cave walls worldwide.

Chaco Canyon Crescent and Supernova (Rob Pettengill)
Petroglyph, Ida Ou Kazzo, Morocco (Abderrahmane Ighi)

Ancient people certainly looked to the skies, because similar stories behind constellations carry across continents and millennia. Archaeo-astronomers study how these cultures understood the heavens and the effects it had on their civilizations. From Chaco Canyon in New Mexico to the dense jungles of Borneo, to caves across Europe, we find repeated patterns of stars, crescent moons, seasonal equinoxes and solstices, supernovae, eclipses and the sudden appearance and retreat of comets.

The appearance of comets became among the first celestial events to be predicted, because short-period comets return in cycles of less than 200 years. Well before the invention of the telescope in the early 17th century astronomers measured these long-tailed visitors against historical records and saw patterns in their return. But some of these comets never fit with historical records. With modern technology we can now identify these as long-period comets from the distant Oort cloud, a bubble of icy bodies well beyond the orbits of Neptune and Pluto. It’s extremely difficult to predict how much these comets will brighten as they approach the sun, with some visible during the day and others only through binoculars.

Comet C/2022 E3 (ZTF) (Dan Bartlett)

Comet C/2022 E3 (TZF) is one such long-period comet, currently making its way through the inner solar system. Discovered at the Palomar Observatory in California on March 2 last year, it reached perihelion — its closest approach to the sun — on January 12, became visible to the naked eye on January 17, and will be closest to us on February 1. Clear skies permitting, step outside and look toward Polaris, the North Star. Draw a line to the moon, and about a third of the way from Polaris, in the constellation Camelopardalis, you may be able to see this ancient interloper. Grab a pair of binoculars or a telescope and you will certainly be able to resolve the fuzzy green tail of this comet, which last graced our skies and was seen by our ancestors nearly 50,000 years ago.

If you would like to learn more about the sky, telescopes, or socialize with other amateur astronomers, visit us at prescottastronomyclub.org or Facebook @PrescottAstronomyClub to find the next star party, Star Talk, or event.

Adam England is the owner of Manzanita Financial and moonlights as an amateur astronomer, writer, and interplanetary conquest consultant. Follow his rants and exploits on Twitter @AZSalesman or at Facebook.com/insuredbyadam.