Scientists predict that asteroid 1996 VB3 will pass close to Earth at a speed of 54,000 km / h.
1996 VB3, an asteroid about 220 m in diameter, will approach Earth on October 20, the same day of the full moon, Newsweek reported on October 18. The closest distance between this object and the Earth is 3.2 million km, nearly 9 times the distance between the Earth – Moon.
1996 VB3 will move at a speed of 54,000 km / h when flying over the blue planet, about 20 times faster than fighters and 17 times faster than bullets fired from rifles.
This is not the only asteroid approaching Earth in the coming days. According to NASA’s Center for Near-Earth Objects, asteroid 2017 SJ20 will arrive 8 million kilometers from Earth on October 25. It is slightly smaller in diameter than 1996 VB3, only about 200 m. On November 2, an asteroid 2017 TS3 with the same size as 1996 VB3 will also “visit” Earth. However, it moves much slower, about 3,600 km/h.
The diameters of the asteroids are only approximate estimates, meaning some asteroids may be as small as half that. Scientists calculate their size based on albedo. It is visible light from the Sun reflected off the surface of an asteroid. This method can sometimes miscalculate because it depends heavily on the reflectivity of the asteroid’s surface.
The albedo of an asteroid depends not only on its size but also on its composition and density. It can also provide clues about color. For example, a “chalk” asteroid with sparse surface matter might look larger than it really is. On the other hand, asteroids with a charcoal-like surface will reflect less light, making the estimated size smaller.
This led scientists to propose a new way to calculate the size. Using infrared light, they were able to detect heat radiating from an asteroid. This may be a better indication of size than visible light. Large objects appear brighter in infrared light, this measurement is also unaffected by albedo. Combining the two methods can help calculate the most accurate asteroid size.
Thu Thao (Follow Newsweek)