Six Questions about "Fire Meteor" in Chengdu: How did it form? Why is it light blue? Will it fall to the ground? Astronomical Popularization Scholars Explaining Operation | Video | On Earth

On the evening of June 22nd, an unidentified flying object appeared in the sky of Chengdu. Many netizens took videos or photos and uploaded them to the internet, sparking heated discussions. The topic of "Chengdu UFO" once made it to the top of the hot search list. That evening, Zeng Yang, Vice President of the Sichuan Astronomical Science Popularization Society, told Red Star News that the "unidentified flying object" was a meteor.

What is the basis for its judgment, how is a meteor formed, and why does it appear light blue? Multiple questions were raised by netizens. On the 23rd, Red Star News reporters gathered and organized relevant questions from netizens, and had a conversation with Zeng Yang.

▲ Screenshots of a bright mobile video captured by netizens in Chengdu

Question 1: How to determine if it is a meteor?

Zeng Yang: By carefully watching multiple videos taken by netizens and judging from the speed, trajectory, and brightness of the object, the possibility of it being an artificial celestial body can be ruled out.

Next, it is necessary to determine which type of natural celestial body it is. Firstly, because it does not have a long tail, the possibility of a comet is ruled out, while meteors do not have a tail. Finally, judging from its brightness, this is not an ordinary meteor, but a brighter fire meteor. At the same time, its burning time is longer, which is also one of the reasons why it is different from other meteors. Under normal circumstances, it can reach 2 to 3 seconds, while the meteor captured by netizens can reach about 5 seconds, possibly due to its higher temperature resistance and larger volume.

Question 2: What are the characteristics of an artificial celestial body?

Zeng Yang: The color is different, which is determined by the material of the artificial celestial body. For example, a while ago, netizens from Beijing and Liaoning captured meteor showers, but most scholars have determined that this is a phenomenon that occurred when the debris of the second stage rocket of the Long March 2-F Yao 5 rocket used to launch Shenzhou 16 fell. The material of the rocket is aluminum alloy, and two-stage rockets often detach from the Earth's orbit, which is about 200 kilometers above the ground. China's aerospace industry has a principle that it will never produce space debris. Therefore, firstly, it is necessary to ensure that the detached two-stage rocket can fall, and secondly, it is necessary to ensure the safety of ground personnel; However, the landing position of the second stage rocket cannot be controlled, so the best solution is to burn it completely in the atmosphere. Its temperature is generally between 700 to 800 degrees Celsius, so its color is red.

Question 3: How did fire meteors form? Why does it appear light blue?

Zeng Yang: A meteor is similar to some small celestial bodies in the solar system that enter the Earth's atmosphere. Its volume is larger than that of ordinary celestial bodies, and its speed when entering the atmosphere is also very fast, so its luminous intensity is relatively high. For observers on the ground, they will see it as if it is on fire, hence it is called a fire meteor. It burns at a temperature of at least 2000 degrees Celsius or above, and it can be visually observed that the combustion temperature of this meteor can reach 4000 degrees Celsius. Such intense combustion causes it to appear light blue.

In fact, if the weather is sunny and there is little light pollution on the suburban mountains, you can almost see fire and meteors in the night sky every night, and sometimes three or four can be seen in one night. It is difficult to see due to strong light sources in the urban area.

▲ UFO video gif captured by netizens over Chengdu

Question 4: Will a meteor fall to the ground?

Zeng Yang: This needs to be judged based on its operating height, speed, and brightness. Fire meteors, also known as meteorites, are called meteorites when they do not fully burn in the atmosphere and fall to the ground.

Between 2017 and 2018, a meteor landed in Shangri La, Yunnan, and the Fangshan Observatory in Panzhihua observed the entire process. At that time, due to high temperature combustion, the meteor disintegrated during flight and produced two shockwave halos, which reflected the entire sky very bright and ultimately landed on the ground. But visually, the meteor Chengdu is very high from the ground and has a great brightness. At the same time, it is a process from dark to bright and then to dark, indicating that it should have burned completely in the air and will not fall to the ground.

Question 5: Some netizens are very concerned about whether such a rapidly falling celestial body will hit aircraft, rockets, and other flying objects?

Zeng Yang: I don't know. Civil aircraft generally have a cruising altitude of around 10 kilometers, while military aircraft will have a higher altitude but will not reach the operational altitude of a meteor. A meteor typically travels at an altitude of around 70 kilometers.

Question 6: What is the scientific research value of observing this meteor?

Zeng Yang: For astronomers and astronomy enthusiasts, the ornamental value of this meteor far exceeds its scientific research value. Because in cities, there are many strong light sources around people, such as high beams in cars and neon lights on high-rise buildings. Under the interference of these strong light sources, this meteor can still be seen so clearly, indicating its high brightness. In astronomy, there is a term called "magnitude", which refers to the brightness level of celestial bodies. The smaller the magnitude value, the greater the brightness. For example, in the Big Dipper system, the brightest star is of positive magnitude 1, the Sun is of negative magnitude 26, and at full moon, it is of negative magnitude 13. On the evening of June 22, Venus, which appeared next to the moon, has a brightness of negative magnitude 6.

From videos taken by netizens, it can be seen that the brightness of this meteor is greater than that of Venus and less than that of the moon, and its brightness may be around minus 10. If you are fortunate enough to see it with your own eyes in the city, it is extremely rare and a very good experience, which can be said to be a kind of enjoyment.