The European Space Agency stated that the number of known asteroids has surpassed the 30,000 mark, only days after Nasa claimed that it had successfully altered the path of an asteroid in deep space. There are a number of asteroids and comets whose orbits put them dangerously close to Earth's orbit around the Sun. There is a chance that the asteroid may approach within 45 million kilometres of Earth's orbit. One million asteroids have been discovered so far by astronomers.
The vast majority of these interstellar rocks have just been discovered within the previous decade, and all of them are located less than 1.3 AU from the Sun (1 AU = Earth–Sun distance).
In the 4.6 billion years since the Sun and the rest of the solar system formed, stony debris like asteroids were left behind. NASA's Joint Propulsion Laboratory defines a near-Earth object as an asteroid that is within 1,300 times the distance between the Earth and the Sun (the Earth-Sun distance is around 93 million miles).
It was in 1898, at Berlin's Urania Observatory, when Carl Gustav Witt and Felix Linke found (433) Eros, the first near-Earth asteroid. According to estimates made by the European Space Agency, the stony asteroid will come within 22 million km (about 57 times the distance to the Moon) of Earth throughout its orbit.
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Hubble and other observatories, like as Gaia, are used in addition to ground-based telescopes to track the asteroid and analyse its orbital motion. Gaia's primary aim is to catalogue one billion stars in the cosmos; comprehending asteroid dangers is an additional bonus.
Some of the near-Earth asteroids detected so far may still travel through Earth's atmosphere and survive entry, but astronomers say none of them pose a threat at the present time and likely won't for at least a century.
