"White light" suddenly appeared in many places in Henan. What is it?

On November 29, a piece of news about a "white light" appearing in the night sky of Henan Province went viral. At around 2 a.m. on that day, residents in Zhumadian, Luohe, Nanyang and other places in Henan Province reported that an unidentified object passed through the sky at a very fast speed, accompanied by a loud noise. According to the live video footage provided by netizens, several white lights flashed in the sky, and the night was instantly lit up, as if it were daytime.

What is that white light falling from the sky?

From the video, we can see that the unidentified object producing white light is falling vertically like lightning. It not only emits dazzling light, but is also accompanied by a loud noise. The entire falling time is short, only a few seconds.

Video screenshots

What exactly is this white light?

"From the video, it is very likely to be a fireball, and it is unlikely to be something else." Guang Hui, executive director of the Jiangxi Astronomical Society, told Science and Technology Daily that the meteors we usually see are very small, equivalent to a grain of sand, and basically disappear after passing through the atmosphere. But judging from the brightness of this time, it should be a fireball.

It is understood that fireballs are actually very bright and massive meteors. Meteors produced when larger meteoroids fall will only emit high brightness when they pass through the stratosphere. The brightness of fireballs is about the same as Venus in the morning or evening sky. They are a special type of meteor that explodes with a bright dazzling flash at the end, usually with visible fragments. Because the brightness is high enough, it can fall well within the range of human color vision. However, due to changes in visual perception, the color of fireballs may be different each time you see them, including red, bright blue, white, and rarely purple.

Are fireballs rare?

The brighter the bolide, the rarer the event.

"There are generally two types of small celestial bodies falling. One is that which burns up in the sky, which is a fireball; the other that does not burn up and falls to the earth is a meteorite." Guanghui said that in fact, the outer space of the earth is full of such small celestial bodies. Thousands of fireballs will fall to the earth every day, but most of them will fall in the ocean and uninhabited areas. Some are small in mass and not very bright and are covered by sunlight, especially in cloudy conditions, which makes it even more difficult to be discovered. Even if it falls in a big city, it will not be so conspicuous because of the dense lights in the city. "At present, we only observe celestial bodies with a diameter of more than 1,000 meters." Guanghui said that small celestial bodies are numerous and dense, and generally will not be observed, so their falling to the earth is a daily phenomenon.

The appearance of a larger fireball is because its meteoroid mass is larger (mass greater than several hundred grams). After entering the Earth's atmosphere, it does not have time to burn up in the high altitude, and continues to break into the dense lower atmosphere, rubbing against the Earth's atmosphere at a very high speed, producing a dazzling light. "Generally speaking, meteors are fleeting, but fireballs have two characteristics, after-stories and deflagrations." Guanghui introduced that an important feature of identifying fireballs is to look at their appearance. One end of a fireball is pointed, which may be the front end or the end. Fireballs may produce two sounds, namely, deflagration sounds and electronic-like sounds. The one discovered in Henan this time was deflagration.

According to astronomy experts, only about one fireball of magnitude -6 or brighter is expected to be seen every 200 hours of meteor observation (magnitude: Sirius -1.6, full moon -12.6, sun -26.7). Therefore, the larger and brighter a fireball is, the rarer it is. Generally, fireballs are discovered mostly in the evening or late at night, and a very small number of very bright fireballs can also be seen during the day.

Source: Science and Technology Daily

◎ Science and Technology Daily reporter Wei Yichen

Editor: Zhang Shuang

Review: Julie

Final review: Liu Haiying