Comet C/2022 E3 (ZTF) is not only fascinating because it has become visible to the naked eye. It also has a mysterious emerald hue. Why is it green?
Comet C/2022 E3 (ZTF) is approaching us. On February 1, 2023, it will be closest to our planet. Know that we can see this comet “ZTF” with the naked eye from France, at the end of January and the beginning of February. 50,000 years after its last passage through the solar system, comet ZTF is back. Certainly for the last time: then comet ZTF should never come to see us again.
In the first photos of the ZTF Comet Shine, we can clearly distinguish its beautiful green color. But where does this particular emerald hue come from? It is related to the chemical composition of the comet, highlighted the Reuters news agency. More precisely, this color is linked to the interaction between carbon-based molecules, which are found in the hair of comet ZTF, and sunlight.
Comets are icy remnants of the solar system, which bear witness to its formation around 4.6 billion years ago. These small bodies revolve around the Sun, with orbits more elongated than those of the planets. Sometimes you can see them with the naked eye from Earth. Determining whether a promising comet will actually become observable is complex, as they are unpredictable objects. Comets can react unexpectedly as they approach the Sun.
It’s the hair of comet ZTF that glows green
As they approach the star, comets heat up and release gases and dust. The nucleus of comets is then surrounded by an envelope called hair, visible in images taken with a telescope, composed of ice and cometary dust. For comet ZTF, the green color is linked to the composition of this hair: it contains diatomic carbon as well as cyanogen. Gold, ” under the effect of sunlight, these two substances glow green “, explains to Newsweek astronomer Gianluca Masi, head of the Virtual Telescope.
Comet ZTF’s emerald color does not extend into its vast dusty tail, which appears white to us in the images. That’s because, Newsweek adds, sunlight breaks down diatomic carbon molecules into carbon atoms before they arrive in the comet’s tail.
C/2022 E3 (ZTF) is not the only comet to show such a color. We remember that comet C/2021 A1 (Leonard) was also tinged with green. Unfortunately, this bright comet had disintegrated in 2021.
The James Webb telescope should also be used to observe comet ZTF and help determine the molecules it produces. Thanks to the location of the telescope in space, astronomers should obtain other data, complementary to those collected from the ground.
