UFOs spotted in the sky over many places, are they aliens or weapons from other countries? The truth is →

Around 6 p.m. on January 14, 2024, people in many provinces and cities in North China, including Beijing, witnessed a "UFO incident." People saw several hazy light groups flying together, without any sound, and then disappeared. During this process, someone also took a picture of the light spot suddenly becoming brighter and bursting out a large aperture.

The picture is taken from a video widely circulated on Weibo

What is this? Are aliens coming to Earth? Or is it some weapon from another country?

What is a rocket cloud?

Let me first state the conclusion. In fact, these strange halos are not the result of aliens landing on Earth, but rather traces left by humans when they used rockets to send things into space. They are called "rocket clouds."

The rocket needs to burn propellants to go up into space. Unlike the narrow and straight tail flame of the rocket when it just takes off, the high-temperature propellants ejected or discarded by the rocket in space will expand rapidly in all directions in a vacuum and weightless environment, "blowing" into several "big balloons" without shells. The dim light spots you see this time are actually the light reflected from the sunlight shining on these "big balloons".

Some friends may ask, it is winter, the sun has already set at 6 o'clock? Yes, it is already dark on the ground, but the rocket has flown to a very high place, so the sunlight can still illuminate the propellant , forming the several light balls we see.

Is it about weapons?

Many netizens have expressed their opinions on this rocket cloud. In addition to those who said it was a UFO, some friends thought it might be some kind of weapon or reconnaissance equipment, because some videos showed that the fuzzy light spots suddenly lit up and looked like they were controlled by someone. Is this true?

Although the rocket cloud has nothing to do with weapons, it is indeed from a foreign country. If we check the recent launch records, we will know that at 4:59 pm on January 14, Beijing time, SpaceX's Falcon 9 rocket was launched from California, USA. This rocket will send 22 Starlink satellites into orbit, and the mission code is SL-7-10. 53 minutes after the launch (5:52 pm Beijing time), the second-stage rocket was turned on again. At this time, the position where the rocket passed by was just visible to the people in North China. And the light spot that everyone saw suddenly became brighter, and a large aperture burst out. We witnessed the second start of the second-stage rocket.

At this point, we not only know the principle of this phenomenon, but also found out which specific launch caused this phenomenon. This UFO (Unknown Flying Object) has completely become a KFO (Known Flying Object).

Many friends also reported that there was no sound during the whole process, which was very strange. This is actually because the rocket is already very high and the atmosphere is too thin for sound to propagate. The reason why these light spots disappeared while flying is because they gradually entered the shadow of the earth.

Sometimes, rocket clouds can have interesting patterns, but because rocket launches themselves are simple trajectories, it is often not a good thing to be too fancy. For example, the spiral rocket cloud that appeared in Norway on the night of December 8, 2009 was caused by a failed Russian intercontinental missile test. Sometimes, when the first and second stages of a normal rocket separate, the first stage of the rocket will spin and fall, which can also cause such a scene.

Why aren't rocket clouds common?

Some thoughtful friends may raise questions: Look, there are obviously more and more rocket launches on Earth, so why are rocket cloud events still so rare? So much so that people find it so novel like this one?

From the previous analysis, we can know that to see this kind of rocket cloud, several conditions are required:

1. The rocket must fly over the ground to be seen. Don't be fooled by the word "space" and think that it is an area visible from the entire earth. In fact, most rocket launches are low-Earth orbit missions, which are only 100 to 200 kilometers above the ground. The visible range is only a circular area with a diameter of about 2,000 kilometers, which only accounts for about 1% of the total area of ​​the earth.

2. The best time to see a rocket cloud is usually at dusk or dawn, when it is night on the ground and day in the sky. Otherwise, the rocket cloud will either be submerged in the skylight or enter the shadow of the earth and cannot be seen by us.

3. *The weather is also very important. The clear skies in North China this winter allowed everyone to witness this wonder. And the icing on the cake was that on the night of January 14, the moon happened to be close to Saturn. Many astronomy enthusiasts saw the rocket cloud while appreciating Saturn and the moon. Of course, there were also unlucky friends who concentrated on watching Saturn and missed the rocket cloud...

From EasyNight's Weibo

It can be inferred that since it usually takes dozens of minutes for a rocket to be launched and enter space, which is enough time for the rocket to go around the other side of the earth, if we launch it domestically, it would not be easy to see a rocket cloud with halo and flash like this time, while those countries over the world have a good chance, just like the SpaceX rocket cloud was seen in North China this time.

But we often see another kind of rocket cloud produced by our own rockets, which is the remnant of the first-stage rocket left after the launch, like the one in the picture below. It is inserted obliquely into space from the lower atmosphere, and is tortuously blown by the wind in the atmosphere and illuminated by the sunlight in the sky. It is really beautiful. For example, such a beautiful rocket cloud appeared during a launch mission carried out by the Taiyuan Satellite Launch Center.

The picture is taken from CCTV News, the source is in the copy

To sum up, just as many UFOs are actually optical phenomena caused by human activities, this rocket cloud is just a small landscape left in space when humans explore space.

Planning and production

This article is a work of Science Popularization China-Starry Sky Project

Produced by: Science Popularization Department of China Association for Science and Technology

Producer｜China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

Author: Qu Jiong Popular Science Writer

Review丨Liu Yong, Researcher, National Space Science Center, Chinese Academy of Sciences

Planning | Ding Zong

Editor: Ding Zong