Astronomers discover moons around an asteroid
– News of September 12, 2017 –
The asteroid (3122) Florence crossed the earth’s orbit, passing only 7 million kilometers from us. It is the largest asteroid to go near Earth since NASA launched its Near-Earth asteroid research program in 1995. The asteroid would have done a lot of damage if it had impacted the Earth. To the surprise of the astronomers who could observe it closely during its passage in the Earth neighborhood, the asteroid has two moons which measure 100 and 300 meters. These moons were probably formed after an impact on the asteroid itself. (3122) Florence is of fairly round shape with a large crater and a ridge line. It goes near the Earth from outside its orbit.
Asteroids and comets represent a danger difficult to estimate for our planet. Relatively small objects enter the atmosphere very regularly, and those that are not completely disintegrated can cause significant damage. The meteor of Tcheliabinsk, a 15-meter-long meteor, exploded in 2013 over the Urals, causing extensive damage. The released energy has been estimated at about 30 times Hiroshima. The shock wave broke a large number of windows, causing more than a thousand wounded. This asteroid is nevertheless relatively small and of low mass. It is suspected that a similar event devastated Siberia on June 30, 1908. The explosion, much more powerful than in 2013, had cut down nearly 60 million trees on nearly 100 km of forest. It is estimated that a meteorite of 60 to 190 meters in diameter is responsible for the event which corresponded to an explosion releasing as much energy as a thousand times the bomb of Hiroshima.
If (3122) Florence collid with Earth, the damage would be immense. It is enough to see the dome-shaped surface of some bodies of the solar system to understand the incredible violence of these impacts. That is why NASA tries to inventory and monitor a large number of asteroids and comets that could be a danger to the Earth. When one of them will come, we hope that humanity will have developed a defense technology. The DART probe must impact an asteroid in 2022 in order to deflect its trajectory. This should serve as a technological demonstrator in case the situation really arises.
Image by NASA / JPL [Public Domain], via Wikimedia CommonsSources