A meteor came to ignite the sky of New Zealand two weeks ago. Small particularity compared to those usually observed, its green color! Researchers explain why.
On July 7, a was also heard, creating a sonic boom over the city of Wellington and across the South Island. Two weeks later, on July 22, another was captured over Canterbury, South Island. This time visible during the night, it lit up the sky flamboyant green. These two close passages of meteors intrigued the inhabitants of the island, who asked for explanations: why this strange green? It resembles to be mistaken the green that one can observe during but beware, the phenomenon is not the same!crossed the skies of New Zealand. Visible in broad daylight,
No, it’s not the same green as for the aurora
When powerfulcross the they can generate what is called a : charged particles come into contact with those in the atmosphere and ionize them. It is the ionization of the contained in the of oxygen which make up approximately 21% of the Earth’s atmosphere, which gives the characteristic green color of . Indeed, after being ionized, it recombines with its , which are then in a so-called excited state. The return to is accompanied by of one whose wavelength corresponds to the color green.
But in the case of a meteor, the mechanism differs. The auroras usually occur between 100 kilometers and 300 kilometers in altitude, in the, while meteors heat up even higher. While the piece of heats up and ignites as it passes through the atmosphere, this time it is nickel and already present on the rocky body which will release a green by vaporizing. If the meteor also contains a slightly yellow streak can be observed, when the are in an excited state.
A brilliant green meteor lights up the sky over Southern India.
— Wonder of Science (@wonderofscience) June 24, 2019