Comet C/2022 E3 (ZTF) brightens as expected, but it also did something unexpected. The comet sprouted a third tail.
The comet made its first appearance in 50,000 years earlier this month.
When comets enter the inner solar system, their frozen surfaces begin to vaporize, carrying dust and gases such as methane, ammonia, carbon dioxide and even water vapor in currents that create a very thin atmosphere around the comet called coma.
External pressure from the sun in the form of solar radiation and winds removes this gas and dust, creating a tail that can be millions of miles long. This primary tail usually glows a light green or pale gray.
Somewhere around Mars’ orbit, the amount of ultraviolet light reaching the comet increases, ionizing any carbon monoxide in the coma, often creating a second blue tail. This ion tail points directly away from the sun as these newly charged particles follow the magnetic path of the solar winds.
Comet ZTF’s rare “anti-tail” points toward the sun. This third tail is made up of larger neutral particles, but they’re not actually heading toward the sun.
This is an optical illusion, created when we cross the comet’s orbit from our viewing position here on Earth.
Michael Jäger captured the image above about a week after perihelion, his closest point to the sun. Jäger, also editor of the Viennese daily Kurier, is an accomplished amateur astronomer who discovered the short-period comet 290P/Jäger and had asteroid 78391 named Michaeljäger in his honor in 2002.
Comet C/2022 E3 ZTF is expected to continue to brighten slightly, and this third tail may become more pronounced as the comet moves toward its closest point to Earth on February 1.
It is still not visible to the naked eye, but may be within range of binoculars under dark skies.