
There are countless asteroids in the solar system – some of them could one day hit the earth, although the chances are slim.
Kassel – Again and again asteroids come close to the earth, small asteroids even hit them occasionally – and again and again there are reports about supposed “killer asteroids” that hit the earth and level it with the ground. Was it a known asteroid of the dangerous ones supposedly threatening the earth? Which asteroids are particularly dangerous and what is science doing to be prepared for a possible impact?
The danger of asteroids is evaluated by experts using two scales: The Turin scale combines the probability of an impact and the energy released in this case to a value that shows the danger of an asteroid. The scale is graded from 0 to 10, with 10 representing “a collision that is certain to occur and which, if struck, (…) threatens civilization as we know it.” Zero stands for “The collision probability is effectively zero or the object is so small that no damage is to be expected.”
Nasa and Esa keep risk lists with dangerous asteroids
Currently (as of January 27, 2023) this year’s asteroid has been found, which is not marked with “0” for “harmless” in the Turin scale: Asteroid 2023 AJ1, which was only discovered on January 14. According to the Center for Near Earth Object Studies (CNEOS) of the US space agency Nasa, it has a diameter of about 280 to 290 meters and the probability that it hits the earth on January 10, 2096 is based on calculations at 1:43,000.
Asteroids that are considered potentially dangerous are listed by the space organizations Nasa and Esa on special risk lists and are regularly observed. In the Fall of Asteroid 2023 AJ1, further observations could lead to the asteroid possibly being removed from the risk list soon – as is often the case in the case of newly discovered asteroids, given our few observational data at the beginning and later calculations can flow in.
Two scales indicate the danger of asteroids
The second scale that indicates the danger of asteroids is the Palermo scale. It is much more complex, but at the end it also outputs a value that indicates the danger of an asteroid. A value of +2 means the hazard is 100 times greater than a background event, a value between -2 and 0 indicates further observation is needed, while values below -2 indicate the asteroid has no consequences.
As of January 27, 2023, there are 27 objects on the risk list of the US space agency Nasa that are being observed. Only a small proportion of them have a rating of -2 or even -1 on the Palermo scale.
These are the most dangerous asteroids according to the Palermo scale
- 101955 Bennu (1999 RQ36): The asteroid named Bennu has the highest value on the Palermo scale: -1.41. The asteroid was discovered in September 1999 and has an average diameter of 492 meters. NASA’s Osiris-Rex spacecraft has visited the asteroid Bennu and collected soil samples that are scheduled to arrive on Earth in 2023. The probability of Bennu hitting Earth by the year 2300 is currently 0.057 Prosent or 1 in 1750.
- 2023 AJ1: The only asteroid currently reading 1 on the Turin scale is just behind Bennu at -1.81 on the Palermo scale. It is possible that the asteroid’s level of danger will decrease if it is observed over a longer period of time (see above).
- 1950 DA: Launching at 7:50 p.m., its 1.3-kilometer-wide asteroid will launch on March 16 at 11:80 p.m. There is a possibility of a collision, but this is a maximum of 0.33 percent (about 1 in 300). Went at Palermo scale is -2.05.
- 2000 SG344: It is 37 meters wide and rated with a Palermo value of -2.79: Asteroid 2000 SG344 was struck on September 16, 2071 with a gain of 0.10 (1:1000). I am May 2028, the asteroid will come within about 3 million kilometers of Earth and will then be looked after by experts.
- 2010 RF12: This asteroid is very small, about seven meters in diameter. Despite this, he IS listed on the Palermo scale with a value of -2.98. According to Nasa, there is about a 10 prosent chance that the asteroid will hit Earth on September 5, 2095. However, since the asteroid is small, the danger is rather small – experts believe that it should become a great fireball in the sky, the rock is likely to shatter in Earth’s atmosphere.
Large asteroids are not a threat to Earth
The largest known asteroids are Pallas (545 kilometers in diameter), Vesta (525 kilometers in diameter) and Ceres (946 kilometers in diameter) – the latter, with a diameter of almost 1000 kilometers, is already considered a dwarf planet. However, the three reliable asteroids pose no threat to Earth.
I’ve heard that it comes with an infamous asteroid nearly small: (99942) Apepa comes very close to Earth on April 13, 2029, and a few more times in later years. Apophis was considered an asteroid with a high collision probability after its discovery in 2004 – it was 2.7 percent at the time and was assigned a value of 4 on the Turin scale (“A closer approach that requires astronomers’ attention”). But this danger is now known and Apophis has been removed from the risk lists.
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NASA tests asteroid defense for emergencies
While there are currently no known asteroids that may threaten Earth in the years to come, asteroids are not to be taken lightly. Researchers are therefore working on plans in the event that an asteroid unexpectedly threatens the earth. Last fall, for example, NASA crashed the “Dart” spacecraft into an asteroid to test whether it could be “pushed” out of its orbit.
The findings are now to be incorporated into planetary defenses – just like the latest findings on so-called “debris heaps” asteroids, which research is expected to be “like a giant space cushion” and theoretically indestructible. (Tab)