An “exotic” green comet, C/2022 E3 (ZTF), which has not come close to Earth since the time of the Neanderthals about 50,000 years ago, is rapidly approaching our planet and is expected to reach its closest distance (perigee) on February 1 or 2, at approximately 42 million kilometers.
The comet was discovered by astronomers at the Zwicky Transient Facility (ZTF) observatory in California in March 2022. It originates from the distant Oort Cloud at the edge of our solar system and is estimated to orbit the Sun approximately every 50,000 years.
Comets, which consist mainly of ice, dust, and gases, usually trace large elliptical orbits around our star. As they approach the Sun, its heat converts the comet's ice into gases and dust, creating the “coma” that surrounds its hard core, as well as its huge spectacular “tail.”.
Images of C/2022 E3 taken so far reveal that it has a greenish hue, believed to be due to its chemical composition, mainly the presence of diatomic carbon, whose molecule emits green light when ultraviolet solar radiation hits it.
Since mid-January, the comet—which has been steadily gaining brightness since last November—has become easier to observe with telescopes or powerful binoculars, and recently it has become bright enough to be visible even to the naked eye, at least from areas with clear, dark skies and no light pollution. In January, amateur astrophotographers managed to photograph the powerful solar “wind” breaking off part of the comet's tail.
C/2022 E3 is moving across the northern hemisphere sky towards the North Star, the brightest star in Ursa Minor, next to which it will appear on January 26. By February 10, it will appear near Mars, and by mid-February, it is expected to have become quite faint as it moves away from Earth.
