In the middle of the night between Thursday 21 and Friday 22 May a giant asteroid will greet the Land with a spectacular (and safe) close passage. It’s about (136795) 1997 BQ, a “space stone“Of Apollo class with a diameter that the NASA estimated to be between 670 meters and 1.5 kilometers. For the European Space Agency (ESA) the length of the asteroid would instead be around 800 meters. Whatever the actual size of the celestial object, ranging from those of the largest skyscraper in the world (Burj Khalifa in Dubai) to those of five Eiffel Tower piled on top of each other, it is one of the largest asteroids classified as “potentially dangerous”By space agencies.
The so-called potentially dangerous objects (Potentially Hazardous Object / Asteroid – PHO / PHA) include all the celestial bodies (both asteroids and comets) that have a diameter greater than 150 meters and that due to their orbit are able to approach the Earth at a distance less than 0.05 astronomical units, equal to 7.5 million kilometers. A Astronomical unit or UA it is in fact the distance that separates our planet from the Sun, about 150 million kilometers (ranges from 147 million kilometers of perihelion to 152 million kilometers of aphelion). In the case of (136795) 1997 BQ, it is estimated that at 03:45 Italian time on May 22 it will pass at a distance of 0.0411 astronomical units from the Earth, or just under 6.2 million kilometers, equal to 16 times the distance that separates us from the average moon (384 thousand kilometers). It may seem like a huge distance, but in exquisitely astronomical terms it is an extremely contained value.
Fortunately, ESA and NASA astronomers guarantee that this is an absolutely risk-free passage for our planet. The impact with such a celestial body, which travels at a speed of 42 thousand kilometers per hour (11.7 kilometers per second), would be catastrophic at the regional level, having the ability to “cancel” entire metropolises. Just think that a big one meteoroid exploded on central Siberia on 30 June 1908 it caused the felling of 80 million trees (on an area of over 2 thousand square kilometers). It had an estimated diameter of only 30 to 60 meters. It was only luck that the collision, known as “Tunguska event”Occurred in a completely uninhabited environment.
However, the incident in Russia cannot be compared to what triggered the extinction of non-Avian dinosaurs and numerous groups of animals 66 million years ago, at the end of the Cretaceous: in that case, a colossus of almost 14 kilometers in diameter called it chicxulub, from the name of the place (on the Gulf of Mexico) where it fell.
Currently among over 2 thousand NEO (Near Earth Object) constantly monitored by NASA and ESA, there are no celestial bodies with trajectories that point straight to Earth. On May 6, 2022, however, the 130-meter asteroid 2009 JF1 as large as the Pyramid of Giza could approach just 2,500 kilometers from Earth.