A flash in the sky of Kyiv: why the fall of a meteorite is “the most likely hypothesis”

For more than a year, Kyiv has been depressingly accustomed to Russian missile strikes. But on Wednesday night, it was not the weapon that set the sky of the Ukrainian capital on fire. Shortly before 22:00, a large bright flash was observed. At first, the local administration blamed the fall on a NASA satellite.

Unless the American agency assured that the latter had not yet entered the atmosphere at that time. This Thursday morning, the Ukrainian space agency finally indicated that it was likely a meteorite. The track was confirmed by astrophysicist Hervé Dol, a professor at the University of Paris-Saclay, based on videos posted on social media.

Given these images, what could be the cause of this large, bright flash?

HERVE DOL: The most likely hypothesis is that the meteor breaks up in the atmosphere because it has the same characteristics as a natural celestial object: the same color, flash, correct vertical direction, and correct speed. When a meteor enters the atmosphere at high speed, it heats up, emits a lot of light, then the heat spreads inward and causes it to break into one or more pieces. It’s a bit like cleaning a carpet with your hand. Initially, the carpet is soft and protects us. But if you rub your hand on it very quickly, it will burn.

How often do meteor showers like this happen?

Yes, it is estimated that several tons of celestial matter falls to Earth every night, sometimes in the form of more or less visible dust, but we do not pay much attention to this. There are a few more exceptional cases where a pebble called a meteorite usually weighs no more than 1kg and can fall and cause damage, such as if you’re unlucky and your car was parked in the wrong place. Then we can go to the field to find these charred bodies that came from the solar system, like recently in Normandy. (mid February, student discovered fragment of an asteroid, which shortly before flashed in the sky).

Before it was refuted, did the hypothesis about the fall of a satellite in the sky of Kyiv seem plausible to you?

Based on the images I’ve been able to see, the answer is practically no, because the falling satellite is moving at a much slower speed. In addition, in the case of a satellite, you usually have several lights on a long cable. However, this is not what we have observed here.