The host's voice came from the speaker: "I invite Ma Dong below, bring us a magic show, origami." ”

The applause rang out, and Atletico Madrid, who was wearing a shirt and bow tie, walked onto the stage, with white clothes and black pants neatly and extraordinary, which immediately caused a scream from a fan girl.

Greeting everyone with a smile, Atletico began his performance.

Unfastening the cufflinks and rolling up his sleeves at will, showing his arms like a magician, he took out a piece of chalk paper from the tray held by his assistant, and showed it to the audience in a matter-of-fact manner, while asking, "Do you see it all?"

Receiving a positive response from the audience, Atletico nodded slightly, "It is said that the flower is a full moon, and the bright moon is in the sky tonight, so I will fold a flower for everyone." ”

As he spoke, he didn't stop in his hands, folding and tearing, and it didn't take long to fold the budding paper flowers. Holding the flower bone in his right hand, Atletico turned to look at the audience, "My flower is amazing, it blooms by itself when I hear the word 'bloom'." Well, I'm not wrong, right?"

Before the flowers finished blooming, the pink paper flowers in the close-up slowly bloomed on their own, like a real flower.

Although they knew that there must be a mechanism in it, everyone still gave a round of applause.

"It's just that the sound blooms and I don't have the power to do it," Atletico continued: "I can still close this flower on its own." ”

As just now, the pink paper flower slowly closed in his hand, but this time it was exchanged for more surprise and applause.

Putting the paper flowers on the tray, Atletico picked up a piece of white paper with a pattern printed on it again, and showed it as usual, "The next one is the Changsanjia rocket that sent Chang'e to the moon." ”

After a while, he had a small short and fat rocket in his palm, and the rocket logo was printed on the outside, which looked similar. Holding his work to face the audience and the camera, Atletico spoke again: "This is a rocket, it can also be launched......"

Then, in front of everyone's eyes, the chubby paper rocket spewed out a puff of white smoke and soared into the air, flying to a height of about four meters, before it fell with all his strength and was caught by his hand.

"Whoa!" The audience burst into applause again.

Sitting in the first row and watching his performance with his own eyes, Zhang Xuyao's eyes were full of surprise, and he turned his head to look at Tang Jiayi next to him, "Sister Jiayi, how did you do this?"

The latter just smiled when he heard this, "Magic or something, it's not interesting to pierce it." ”

"Huh, don't say it, I'll go online to find it," Zhang Xuyao muttered and picked up her phone.

On the stage, Atletico performed folding planes and cars, and they could also fly and run, but they didn't attract her attention.

Later, Atletico Madrid bowed, a pair of beauties in ancient costumes took the stage, and elegant and cheerful ancient music soon sounded in the stereo.

Ancient music and dance have always been Zhang Xuyao's favorites, if in the past, she would definitely keep an eye on the dancers on stage, and conduct all-round observation and evaluation of their dance posture, choreography, song selection, costumes, appearance, height, makeup, accessories and other details.

However, now she is on the stage without intention, and all her attention is on the mobile phone.

As for the object of attention, it is not Atletico Madrid's origami magic.

There were a lot of search results online, and she even found movable origami with rubber bands, but it was clearly not Atletico's.

Then, her attention was diverted by the meteor that had just fallen, and she chased the relevant news along the hot search keywords.

Meteors aren't that uncommon.

Vacuum is not as empty as it sounds, especially in the interior of star systems, near planets. The Earth revolves around the Sun, and every day it hits countless particles of cosmic dust and rock fragments, some of which are left by the solar wind, some are ice slag left by comets passing by, some are stone chips left by asteroids passing by, and some are other sources of things. Once they hit the outer atmosphere, they all end up falling to the ground.

Micron-sized dust particles carry too little kinetic energy, and they decelerate a lot at the top of the atmosphere and then slowly drift to the ground, in the sea, in the soil, on the roof, but everywhere it is difficult to detect and collect. If the dust particles are larger, they can maintain a higher speed flight for a longer time, and then rub the air to burn themselves, leaving a trace of light and heat in the air. If it's just bright enough, the weather is fine, the air is clean, and someone looks up, they can see a bright line across the sky, which is called a meteor.

Most of the dust particles are very small in size, and the meteors that are transformed by them are faint and fleeting, and although they are as large as 100,000 a day, they are still difficult to detect and notice. If it is large enough to be "burn-resistant" and fall at the right angle, it can form a brighter, longer and longer obvious wake, which is vividly called a fireball.

Meteors are identified as having a brightness of less than -3 (magnitude, the smaller the value, the brighter it is), with a mass of more than 5 grams, and the number of meteors appearing per day drops to thousands. However, most of them have landed in the ocean and no man's land, and only a small number of meteors have been widely noticed by the public and reported by the media.

In terms of size and brightness, this time the meteor is actually nothing, far less than the one on March 11 (the explosion power is equivalent to 2,900 tons of TNT), but the latter fell into the vast Atlantic Ocean at midnight, and no one paid attention to it except astronomical institutions, while the former crossed the sky over Shangri-La, a world-famous scenic spot at 8 o'clock in the evening, and there were many sightings by local people and tourists, which naturally attracted large-scale reports and attention.

In addition, Bee's astronomical applications such as "Meteor Chaser", "My Star", and "Pretend to be in Space" also pushed the video of the meteor from the satellite perspective to users for the first time, which further heated up the popularity of Shangri-La meteors. Limited by size and cost, the observation ability of microsatellites is actually very limited, and it does not have the ability to find and record meteors.

Because of the low altitude of the air blast, there is speculation that it may not have burned out and that there should still be wreckage falling to the ground. When they saw the meteorite news announced by the NASA Near-Earth Object Research Center CNEOS, the "meteorite hunters" at home and abroad immediately took action, wanting to be the first to get their hands on the meteorite.

Interestingly, less than an hour after the meteorite landed, the almighty Taobao seller put it on the shelves and offered a sky-high price of 10,000 yuan per gram, and I don't know if it's true or not.

After thinking about it, she handed her phone to Atletico, who had just returned to the audience after the performance, to hear what the experts had to say.

"Do you still need to ask?" Atletico Madrid had a look of disdain on his face as his gaze swept over the phone screen, "It's night, Shangri-La is still a high-altitude mountainous area, and in this case, he can still pick up a meteorite as soon as possible, unless the meteorite hits the glass of their house, or simply hits his head." ”

"Well, isn't it?" Teacher Zhang was slightly stunned, and then asked, "Isn't the meteor bright and shining? It should be easier to find, right?"

Atletico glanced at her, lowered his head and typed five words in the address bar of the browser, but couldn't help laughing when he looked down, "Look, this is your Du Niang!"

took the phone, Zhang Xuyao couldn't help but be a little annoyed, the search keyword was "no light flight period", but the search results that Du Niang responded to were only "flight", but there were a bunch of keywords such as "x girl full set of no light" in related searches that made people blush.

"No way, the results of the honey search are too serious and too slow, social hotspots, celebrity gossip are a few beats slower than Du Niang," she explained, she changed the search engine to a honey search, this time I finally saw a more serious answer, the first is the encyclopedia entry of the honey search without a light flight period, the second is the news that the camera accidentally photographed a meteorite without a light flight, and the third day is a journal paper on the unmanned aerial vehicle optoelectronic platform.

Meteorites emit light because they rub the air at high speed, and because the speed at the end of the flight is greatly reduced, their temperature and brightness will also drop significantly, so it is called dark flight. At the same time, due to the decrease in speed and volume (combustion loss, air explosion disintegration), the meteorite at the end of the flight is more susceptible to the influence of air flow and randomly changes its trajectory, which brings great trouble to meteorite hunters on the ground.

If it is an iron meteorite (meteorite), you can also use a metal detector or magnet to help find it, but if it is a stony meteorite, you can only look for it with the naked eye. Meteorites that have just fallen will cause impact marks on the ground, and they also have a unique appearance caused by high temperature melting, so if you are lucky and experienced, you can indeed spot it visually.

After reading the encyclopedia information and looking at the video in the second news, Zhang Xuyao raised his head, "So, brother, do you think they will definitely not be able to find that meteorite?"

"It's really difficult," Atletico nodded, "Most of the meteorites that have been discovered are from the Antarctic ice sheet, and a small part are from the desert Gobi region of Africa and Central Asia, which are relatively empty and the ground is of a single color, which is conducive to visual search." The mountainous areas are wooded and the paths are rugged, so it has never been a good place to find meteorites, but this time the location of the drop is still a high-altitude mountainous area, and it is really difficult to find it. ”

"Since I can't find it," Zhang Xuyao tilted her head, "Why are so many people running over there?"

According to information on the Internet, in just one hour, many people bought tickets to Shangri-La.

"Everyone has a fluke mentality, if the meteorite is big enough, there is still a possibility of finding it. Besides, these people are not all going for meteorites, meteorite researchers and enthusiasts should want to find freshly fallen meteorites, and many of those meteorite dealers are going to sell tools, sell appraisal and auction services, and there may even be profiteers who plan to bury mines. ”

"Buried mines?"

"Bury a real meteorite in the ground, and then dig it out yourself and pretend to be a newly discovered one. The value of meteorites is mainly research significance and commemorative significance, the vast majority of meteorites are not valuable, a small piece only needs a few dozen pieces, and even a lot of meteorite iron has been melted into meteorite swords or ornaments. Usually only those meteorites with clear provenance and good enough fame can be sold for a high price, and there is room for counterfeiting and profit. ”

Zhang Xuyao became interested, and Tang Jiayi on the side also turned her head, "Oh, how high is the price?"

"The price is messy and there is no fair price. For example, lunar meteorites have a minimum of $600 a gram and a maximum of $40,000 a gram, a difference of dozens of times. ”

Tang Jiayi has been paying attention to this side, and at this time she interjected, "There are also meteorites on the moon?"

"Uh-huh," looking up at the blurred moon overhead, Atletico withdrew his finger that was about to point to the crater, "The moon has no atmospheric protection, the escape speed is only 2.38 kilometers per second, and when an asteroid hits, there will always be some faster debris that will leave the lunar orbit and enter the Earth's orbit, and then after a long time close to the Earth, and finally fall on the ground." ”

Tang Jiayi nodded, but Zhang Xuyao was still puzzled and continued to ask: "Wait! How do you know that the meteorite came from the moon? Now you can track these things accurately?"

"There's no need to track. The Apollo program brought back a total of 381.7 kilograms of lunar rock specimens from the moon, and a large piece of the United States left it for its own research, and the rest of the debris was used as a national gift to other countries, first, because it was of great significance from the moon, and secondly, to prove that the moon landing project was real. They sent more than 130 countries before and after, and our country also got 1 gram in 1978, and with these lunar rock specimens from certain sources, other lunar meteorites can be found through comparative analysis, and about 200 kilograms have been found so far. ”

"Ah!" Zhang Xuyao heard about this for the first time, and couldn't help but exclaim, "I remember the right flowers, the Apollo program seems to have been completed by tens of billions of dollars, right?

Tang Jiayi added with a smile: "It's 49.2 billion US dollars, and it's still the US dollar before the collapse of the Bretton Woods system, and a lot of dollars that are constantly depreciating now." ”

"That can't be said," Atletico shook his head slightly, "not to mention the contribution of the Apollo program to the collapse of the Soviet Union and the leading role of scientific research and social productivity, the value of those moon rocks is also quite large." Without these hard-earned credible samples, scientists would not have been able to find the ones from the moon in the meteorite pile. Moreover, the meteorite falls through a high-temperature and high-pressure process, the physical structure and chemical composition are damaged to a certain extent, and it falls to the ground and lies in the wild for I don't know how many thousands of years, and it has been weathered and eroded for a long time, and the structure and composition have been further changed, but the research value is far less than that collected by Apollo. ”

"Oh," Zhang Xuyao nodded, "Since it's not worth much, why are there still people hyping this?"

"Of course, the hype is because it is profitable, the dinosaur egg fossil is a stone with a special origin in the final analysis, and it is not the same as someone who rushes to buy and hoard it? ”

Teacher Zhang became curious, and hurriedly asked, "What advantage?"

"Dinosaur eggs belong to buried cultural relics, private excavation and trading violates the cultural relics law, meteorites come from space, not cultural relics or mineral deposits, which belongs to the legislative gap. ”

"Aha, doesn't the country care?"

"Ordinary meteorites have no research value, and the economic benefits are pitiful, so they can't be specially cultivated for it. ”

(End of chapter)