"Impact probability is100%": 2022eb5 became the fifth asteroid discovered before it hit the earth.

Most asteroids that hit the earth were discovered many years after the event, usually millions of years later. What is the evidence? About 200 known craters have left "scars" on the earth's surface, telling how our planet and life on earth were greatly shaped by the violent collision of ancient space rocks. Recently, "2022 EB5" became the fifth asteroid in the history of human observation that was discovered before it hit the Earth.

A warning of some effects

On March 0 (UTC) 1 19:24, astronomer Krisztián Sárneczky discovered a bright and fast-moving new celestial body in the sky with the 60 cm Schmidt telescope of the Hungarian Pizkesteto Observatory. He quickly collected four observation data and reported his findings to the Asteroid Center (MPC) only after 14 minutes, and originally named the object "Sar2593".

These results were quickly published and used by automatic impact assessment systems around the world to estimate the possibility of impact: it seemed unlikely at that time, less than 1%.

Christian continued to observe this celestial body, and made 10 observation shortly after its discovery, and submitted it to MPC again. However, these have led to a completely different situation. Almost a full hour after the object was discovered at 20: 25 UTC, the "Meerkat" monitoring system of ESA issued an alarm to NEOCC based on the accumulated observation data.

The collision probability is now 100%, which will occur in less than one hour, between 2 1, 2 1 and 2 1: 25 UTC. The impact position of this new celestial body can be predicted to the nearest thousand kilometers, which is expected to be hundreds of kilometers north of Iceland.

Rapid response to fast space rocks

In response to ESA's "Mongoose" warning and other similar warnings, professional and amateur observers in Europe and Asia quickly began to observe the coming impact objects. Because this celestial body is very close to the moon (the distance from the moon is about 1/7) and it moves rapidly in the sky, it is very challenging to find it.

Another observatory-Kysuce in Slovakia-quickly reported its successful observation results, as well as many detection results of the original discoverer. With the addition of these new data, the location of asteroid impact can be determined more accurately: the asteroid will enter the atmosphere about 140 km south of Jan Mayen at 2 1: 22: 42 UTC-less than two hours after its discovery.

Judging from the observed brightness, this celestial body seems very small. Its diameter is about one meter, which poses no threat to the earth, because at this size, it will completely burn in the earth's atmosphere.

Shortly after the estimated impact time, the Asteroid Center named this asteroid "2022 EB5", which became the fifth known impactor observed in space before hitting our earth and the first one found in Europe.

Unfortunately, there is no definitive visual or video detection of fireballs at present, which may be because the impact site is remote.

However, due to the existence of the international infrasound detector network, there is independent evidence that the impact did occur. Impact signals were detected from Iceland and Greenland, indicating that the released energy was approximately equivalent to an earthquake with a magnitude of 4.0.

Why only five times so far?

It is estimated that 40 to 100 tons of space materials hit the earth every day, most of which are very small particles. Larger celestial bodies, similar in size to 2022 EB5, are expected to hit about 10 times a year. So, why were only five asteroids detected before the impact?

The news here is quite positive. Large asteroids are easier to find. Although they can cause great harm, fortunately, they are relatively rare. Now that we know the location of most asteroids, we can say with certainty that they are safe, at least in the next 100 year. The international community continues to search for every asteroid.

Smaller asteroids are more common and hit the earth much more frequently, but they have less influence and are more difficult to find. The five asteroids discovered before the impact were all discovered after 2008, which shows that the observation technology of asteroids has been greatly improved in the past few years.

More asteroids are coming.

More special sky scanning telescopes are being prepared, including the first most advanced compound eye telescope of ESA to be built in Montmufara, Italy. The new European telescope will divide each image into 65,438+06 smaller sub-images and expand its overall field of vision-similar to the technology used by flies to compound their eyes.

As part of the global efforts to find dangerous celestial bodies such as asteroids and comets, ESA is developing an automatic telescope for night sky survey. This telescope is the first in the future network. It will completely scan the sky and automatically identify possible recent celestial bodies for human researchers to track and then check.

"The extremely wide field of vision of the new telescope will enable us to cover a large sky in one night," said Detlef Kosny, acting director of the Planetary Defense Department of ESA. "This will reduce our chances of missing any interesting celestial bodies."

As researchers predict the improvement of asteroid impact ability, their preparation will also be improved. For a medium-sized impact that can explode in the air, it means an opportunity to warn people to stay away from windows that may be broken in the explosion. For larger objects, this means that there is an opportunity to prepare for the asteroid deflection mission to completely prevent collisions.