More than 30,000 near-Earth asteroids (NEAs) have now been identified in the Solar System, marking a huge milestone for astronomers.
According to the European Space Agency (ESA), there are currently 30,039 identified near-Earth asteroids, and the number is rapidly increasing.
Near-Earth asteroids are stony entities that orbit the Sun on a path that brings them near Earth’s orbit; some of them have the potential to strike our planet.
According to the ESA, 1,425 have a “non-zero chance” of colliding with Earth and are consequently being monitored by a network of telescopes.
According to ESA, the vast bulk of the 30,000 NEAs were identified in the previous ten years as a result of rapid technological advancement.
“The good news is that more than half of today’s known near-Earth asteroids were discovered in the last six years,” said Richard Moissl, chief of planetary defense at the European Space Agency.
As this latest detection milestone of 30,000 demonstrates, and as more telescopes and detecting methods are developed, it’s only a matter of time before we’ve found them all.
10,000 of the 30,039 NEAs are estimated to be greater than 460 feet (140 meters) in diameter, and 1,000 are estimated to be larger than 3,280 feet (1 kilometer) in diameter, underscoring the necessity to monitor these space rocks.
Approximately a third of the nearly one million asteroids found so far in the Solar System are NEAs.
The majority of asteroids exist in the asteroid belt, a ring-shaped region of the Solar System roughly positioned between Jupiter and Mars.
On August 13, 1898, German astronomer Carl Gustav Witt found the first-ever NEA, 433 Eros, at the Berlin Observatory.
Its orbit brings 433 Eros within 13.5 million miles of Earth, which is 57 times the distance between the Earth and the Moon. 433 Eros is known for its peculiar, elongated shape and rocky composition.
In addition to being the first Near-Earth Asteroid to be found, 433 Eros was the first asteroid to be orbited by a spacecraft and the first to have a spacecraft land on it.
The NEAR Shoemaker spacecraft investigated Eros for a year from close orbit before landing on the surface in February 2001.
When an asteroid’s track brings it within 1.3 astronomical units (AU) of the Sun, it is considered a near-Earth object.
A single astronomical unit equals the distance between the Sun and the Earth (93 million miles), thus many are still quite distant from us.
Experts can identify their position and determine whether they will strike Earth hundreds of years in advance.
‘Of course, any asteroid identified near Earth qualifies as a near-Earth asteroid,’ said Marco Micheli, an astronomer at the Near-Earth Object Coordination Centre of the European Space Agency.
‘New objects are detected over time, their movements are examined, and their future positions can be forecasted with just a handful of data points from different nights.
Depending on the quantity and quality of observations, this might stretch decades or even centuries into the future.
According to NASA’s Near-Earth Object Program, the Earth is struck by a football field-sized rock every 5,000 years and a civilization-ending asteroid every million years.
NASA established a planetary defense program, which includes the Double Asteroid Redirection Test (DART) mission, to combat the threat of asteroids that may one day come dangerously close to Earth.
DART was launched from California in November, and its 10-month voyage was ultimately completed when it collided with the asteroid Dimorphos last month.
Dimorphous, with a diameter of around 560 feet, orbit Didymos, a bigger asteroid located approximately 6.8 million miles from Earth.
DART collided with the space rock at over 14,000 miles per hour and was destroyed upon contact, while Dimorphos suffered a “little shove” to slightly modify its direction.
The spacecraft was able to reduce Dimorphos’ orbit by 32 minutes, as stated by NASA earlier this month.
Neither Dimorphos nor Didymos pose a threat to Earth; rather, the $325 million (£298 million) mission served as a dress rehearsal for what might be necessary if a space rock ever did endanger our planet.
