Near Miss Day, although rather obscure, is celebrated yearly on March 23. The holiday commemorates the day that a large asteroid, named Asclepius, barely missed Earth on Thursday, March 23, 1989.
Asclepius had a diameter of .0431 kilometers, comparable to the size of a football field. According to nationaltoday.com, many geophysicists believe that the collision of Asclepius with the Earth would have wreaked havoc, resulting in the release of energy comparable to a 600-megaton atomic bomb.
Nationaltoday.com illustrated a timeline of events regarding Asclepius. It begins with Wednesday, March 22, 1989, when 4581 Asclepius passed Earth by at a distance of approximately 500,000 miles. Then on Friday, March 31, 1989, astronomers Henry Holt and Norman Thomas discovered that Asclepius had passed by Earth. In August of 1989, scientists discovered another asteroid that was very close to Earth but missed. In 1990, scientists confirmed the diameter of Asclepius to be between 300 meters and 800 meters.
According to astronomy.com, NASA has only mapped 40% of the potentially dangerous asteroids that could crash into Earth. New projects will boost that number, and upcoming missions will test tech that could prevent collisions. In November 2021, NASA launched the world’s first full-scale planetary defense mission as a proof of concept: the Double Asteroid Redirection Test, or DART. The large asteroid Didymos and its small moon currently pose no threat to Earth. In September 2022, NASA plans to change the asteroid’s orbit by crashing a 1,340-pound (610 kg) probe into Didymos’ moon at a speed of approximately 14,000 mph (22,500 kph).
NASA stated that the current known asteroid count is 1,113,527. Asteroids are classified by their composition and orbit. According to NASA documentation, the three composition types are C-type, S-type and M-type. C-type asteroids are also referred to as chondrite and are described as containing clay and silicate rocks. S-type asteroids are considered “stony” and are made up of silicate materials, nickel and iron. M-type asteroids are called metallic and have iron in their center. Additionally, asteroids are classified by their orbit and are considered to be part of the main asteroid belt, Trojans or near-Earth asteroids. Most asteroids orbit within the belt between Mars and Jupiter and therefore are within the main asteroid belt. Trojans share orbit with a larger planet, but do not collide with it. Near-Earth asteroids are those that cross Earth’s orbit and are also referred to as Earth-crossers.
Asteroids are also given names and a number, just as above 4581 Asclepius. NASA stated, “The International Astronomical Union’s Committee on Small Body Nomenclature is not very strict when it comes to naming asteroids. As a result, out there orbiting the Sun we have a giant space rock named for Mr. Spock – a cat named for the character of “Star Trek” fame. There’s also a space rock named for the late rock musician Frank Zappa. There are more somber tributes, too, such as the seven asteroids named for the crew of the Space Shuttle Columbia killed in 2003. Asteroids are also named for places and a variety of other things. (The IAU discourages naming asteroids for pets, so Mr. Spock stands alone). Asteroids are also given a number, for example (99942) Apophis. The Harvard Smithsonian Center for Astrophysics keeps a fairly current list of asteroid names.”
Near Miss Day is certainly a day to be thankful for, as Earth got a second chance. NASA provides a lot of information on asteroids and the technology being used to monitor them. You can visit solarsystem.nasa.gov for up-to-date details and to review photo galleries of known asteroids.