Our planet is currently defenseless against “city killer” asteroids, noting “we don’t know where they are,” a leading scientist has warned this week.
Astronomer Kelly Fast, NASA’s planetary defense officer, is most worried about these medium-sized asteroids, which are small enough to go undetected but large enough to cause significant damage upon hitting the Earth.
Speaking at the conference of the American Association for the Advancement of Science (AAAS) in Arizona, Fast said: “What keeps me up at night is the asteroids we don’t know about,” according to The Sun.
Fast noted that small asteroids are “hitting us all the time so we’re not so much worried about that.” She added that scientists are also less concerned about “the large ones from the movies because we know where they are.”
However, they are most worried about “the ones in between, about 140 metres [around 459 feet] and larger, that could really do regional rather than global damage, and we don’t know where they are.”
“It’s estimated there are about 25,000 of those, and we’re only about 40 percent of the way through,” Fast noted. “It takes time to find them, even with the best telescopes.”
Asteroids are small, rocky masses left over from the formation of the solar system about 4.6 billion years ago. They are found concentrated in the main asteroid belt, which lies around the sun between the orbits of Mars and Jupiter.
The so-called “near-Earth objects” are asteroids whose orbits bring them within 120 million miles of the sun and into the Earth’s “orbital neighborhood.”
Back in February last year, data from the Center for Near Earth Object Studies (CNEOS) found that the impact probability of an asteroid known as “2024 YR4” in 2032 was at 3.1 percent, which was “the highest impact probability NASA has ever recorded for an object of this size or larger,” the space agency said at the time.
Further studies found that “the object poses no significant impact risk to Earth in 2032 and beyond,” the space agency noted.
Most near-Earth objects, NASA added, have orbits that “don’t bring them very close to Earth, and therefore pose no risk of impact.”
However, a small portion of them, known as potentially hazardous asteroids (PHAs), do require closer attention. Measuring more than 460 feet in size, PHAs have orbits that bring them within 4.6 million miles of the Earth’s orbit around the sun.
Despite the number of PHAs out in our solar system, none are likely to hit our planet any time soon.
“The ‘potentially hazardous’ designation simply means over many centuries and millennia, the asteroid’s orbit may evolve into one that has a chance of impacting Earth. We do not assess these long-term, many-century possibilities of impact,” Paul Chodas, manager of the CNEOS, previously told Newsweek.
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