As there are hundreds of millions of asteroids in our Solar System, new asteroids are often discovered. It also indicates that near collisions between asteroids and Earth are rather frequent.
Some of these near-misses result in an asteroid striking Earth, sometimes with devastating repercussions.
It has been reported that the freshly found asteroid 2023 BU traveled quite near to Earth. On January 27, six days after being discovered by amateur astronomer Gennadiy Borisov in Crimea on January 21, 2023 BU traveled within 3,600 kilometers of Earth’s surface (near the southern edge of South America).
This distance is just slightly greater than the distance between Perth and Sydney, and is less than one percent of the distance between the Earth and the Moon.
The asteroid also traveled through an area of space containing a considerable number of satellites created by humans that orbit the Earth.
All of this makes 2023 BU the fourth-closest known asteroid approach to Earth, excluding those that have actually collided with the planet or its atmosphere.
The only noteworthy aspect of 2023 BU is that it traveled so close to Earth. The diameter of the asteroid is believed to be between 4 and 8 meters, which is on the smaller end of the size spectrum for asteroids.
There are potentially hundreds of millions of such objects in our Solar System, and it is feasible that 2023 BU has passed near to Earth several times in the last millennia. Up until recently, we were unaware of the reality.
On average, a 4-meter-diameter asteroid will strike Earth every year, while an 8-meter-diameter asteroid will do so about every five years (see the infographic below).
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Asteroids of this size pose minimal threat to life on Earth since they disintegrate in the Earth’s atmosphere. They generate dazzling fireballs, and some of the asteroids may reach Earth as meteorites.
With the discovery of 2023 BU, its orbit around the Sun can be determined and its future trips to Earth may be forecast. There is an estimated 1 in 10,000 probability that 2023 BU will strike Earth between 2077 and 2123.
Therefore, we have little to worry from 2023 BU or any of the countless millions of such objects in the Solar System.
To pose a substantial threat to life on Earth, asteroids must be at least 25 meters in diameter; to threaten the existence of civilization, they must be at least one kilometer in diameter.
It is predicted that there are less than one thousand such asteroids in the Solar System, and that one of them may strike Earth every 500,000 years. We have information on around 95% of these things.
Asteroid 2023 BU made the fourth closest approach ever recorded. The three closest approaches were caused by extremely tiny asteroids detected in 2020 and 2021. (2021 UA, 2020 QG and 2020 VT).
Throughout the approximately five billion years of the Solar System’s life, asteroid 2023 BU and numerous other asteroids have passed extremely close to the Earth, and this will continue in the future.
In recent years, our capacity to identify asteroids of this size has evolved, allowing us to assess any potential risks. The fact that an object around five meters in size may be spotted from tens of thousands of kilometers away by a highly devoted amateur astronomer demonstrates that the equipment necessary to make big astronomical discoveries is accessible to the general population. This is quite exciting.
Together, amateurs and experts may continue to uncover and classify things so that danger analysis can be conducted. The Double Asteroid Redirection Test (DART) mission, which successfully crashed a spacecraft with an asteroid and altered its course, was a very significant event in the last year.
DART renders realistic the possibility of diverting an asteroid away from a collision track with Earth, assuming a threat analysis indicates a significant danger with sufficient lead time.
