The Green Comet Lights Up the Sky This Winter

By Emma Rathgeber

In March of 2022, California astronomers were using the Zwicky Transient Facility telescope to search for various types of distant celestial bodies, such as emerging black holes and supernovas, when they unintentionally came across a form that was blurrier than expected. They immediately identified the observation as a comet, and named it C/2022 E3

In time, however, the small celestial body was given the more colloquial name “the Green Comet,” due to its stark green hue. However, this wasn’t the only part of the story that made the lucky sighting so remarkable The Green Comet’s flyby in early 2023 made history, as it marked the comet’s first return to Earth since the Stone Age

The sighting of the Green Comet was unlike other meteor word sightings That’s because this flyby was not an appearance: it was a reappearance. The colorful comet paid a visit to Earth about 50,000 years ago, although it is unlikely that societies of the time were able to fully appreciate the spectacle. Thankfully, modern technologies allow us to view and study this unique phenomenon in all its green glory. But what makes the Green Comet, well, green? As a meteor flies through space, it reflects different wavelengths of light based on its orbital position The comet’s chemical composition also plays a role, as the diatomic carbon found in the coma glows green under sunlight. This coma is formed when ice on the comet sublimates as the comet flies by the sun. This direct change from solid ice to gas produces a fuzzy cloud of blur around the icy sphere. Together, these two factors give the Green Comet its distinctive hazy-green hue

Unfortunately, the narrow window of time for enjoying this vibrant view has closed

The Green Comet escaped our range of visibility in midFebruary to continue its trajectory past Mars and into the outer solar system

Ultimately, the comet will return to the Oort Cloud, the home of many similar icy planetesimals. This was likely humanity’s final goodbye to the Green Comet, as the comet’s extremely wide orbit ensures that it will be another 50,000 years until another viewing Until then, we wish the Green Comet luck in its journey throughout the vast expanses of the solar system.