The Green Comet will be closest to earth on Feb 1. Here’s the science behind its ghoulish glow.

Comet ZTF, as photographed on January 18, 2023.
A green comet is whizzing past the earth for the first time since the ice age. 
The comet’s head shines green, while its tail shines white. 
Scientists found out why it glows this way in 2021, and it comes down to physics. Here’s how it works. 

A green comet called C/2022 E3 (ZTF), or Comet ZTF for short, is nearing its closest approach to earth for the first time since the ice age. 

Comet ZTF will come within 26 million miles (42 million kilometers) of our planet on Wednesday, about a third of the distance between the earth and the sun. 

The green comet, which last passed through the inner solar system about 50,000 years ago, will be at its brightest during this time.

Comet ZTF (C/2022 E3) taken at NAOJ Mitaka Campus on January 31, 2023.

Like other comets, ZTF has a stunning green hue, although skygazers may be unable to see this with the naked eye. 

The secret of the comet’s green glow lies in a molecule called diatomic carbon, C2,…

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This article was written by [email protected] (Marianne Guenot) and originally published on