Astronomers refer to it as a “planetary killer,” which could cause an ecological extinction disaster if it collides with Earth.
Recently, astronomers discovered a massive asteroid named 2022 AP7, with a diameter of 1,500 meters. Its orbit lies within the orbit of Earth and intersects with Earth’s trajectory. Large asteroids like this are termed “planetary killers,” as a collision with Earth could lead to catastrophic ecological disaster.
Orbit of asteroid 2022 AP7.
This type of asteroid is difficult to detect because it is hidden in the direction of the Sun, and the intense sunlight obscures their visibility. Advanced telescopes such as Hubble and Webb must be shielded from the blinding light of the Sun, which can damage their delicate optical systems and hinder their ability to detect such asteroids.
Astronomers took advantage of a brief window at dusk and used the Dark Energy Camera (DECam), installed on the 4-meter Víctor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile, to explore three asteroids orbiting Earth. Besides 2022 AP7, the other two asteroids are numbered 2021 LJ4 and 2021 PH27, both measuring over a kilometer in size.
While these two asteroids have less intersecting orbits with Earth, 2022 AP7 poses a significant threat to our planet.
When 2022 AP7 was discovered, it was moving 30 million kilometers away from Earth, seemingly a safe distance. However, calculations indicate that its orbit will continue to approach Earth, and it may come dangerously close at some point in the future.
When 2022 AP7 was discovered, it was 30 million kilometers away from Earth.
Astronomers have not yet been able to predict when 2022 AP7 will come close to Earth, and it will not appear in 2023.
In fact, in the vicinity of Earth, up to 19,500 asteroids have been detected, with more than 2,000 asteroids having diameters greater than 1 kilometer and hundreds more measuring 4 kilometers across. The orbits of these asteroids intersect with Earth’s orbit, and any asteroid coming close to Earth could pose a threat to humanity.
Sixty-five million years ago, a 10-kilometer asteroid struck Earth, causing the extinction of the dinosaurs, which had dominated the planet for 165 million years. Eighty-five percent of species went extinct, fundamentally altering the evolutionary course of ecosystems on our planet.
This collision left a crater approximately 280 kilometers in diameter in the Yucatán Peninsula of Mexico, with an impact energy equivalent to about 120 trillion tons of TNT, more than 10,000 times the total yield of all nuclear bombs in the world combined.
The orbital speed of 2022 AP7 is 17.38 km/s.
According to information disclosed by scientists, the orbital period of 2022 AP7 (one orbit around the Sun) is 1,830 days (5.01 years), with a aphelion distance of 5.01 AU (astronomical units; 1 AU is about 150 million kilometers) and a perihelion distance of 0.83 AU. It is considered to have an average diameter of about 1.5 kilometers.
The orbital speed of 2022 AP7 is 17.38 km/s, but it will not be traveling at this speed upon impact with Earth. Instead, it will be combined with the rotational speed of Earth, leading scientists to estimate it will collide with Earth at a speed of 20 km/s.
Using the formula for impact energy E=1/2mv^2, we can deduce that the energy of 2022 AP7 upon colliding with Earth is approximately 7 x 10^20 J, equivalent to 7 trillion trillion joules, or about 167.3 billion tons of TNT, which is equivalent to approximately 12.87 million atomic bombs detonating simultaneously in Hiroshima.
It is important to note that the total number of nuclear warheads in the world contains a destructive power of less than 10 billion tons of TNT; thus, the energy of 2022 AP7 is approximately 17 times greater than the combined power of all nuclear bombs on Earth.
Although this calculation may not be entirely accurate, the impact energy will also vary based on the collision speed and density of the asteroid. Historical experience and scientific research indicate that if an asteroid measuring several tens of meters strikes a densely populated area, it could destroy a city; if an asteroid larger than 100 meters falls, it could obliterate a country. Accordingly, an asteroid larger than one kilometer colliding with Earth would possess enough power to bring catastrophic disaster to humanity and the ecosystem.
Tsunamis and massive earthquakes would successively strike the world, and coastal cities could be completely submerged; fire and smoke would obscure the Sun, and those creatures that survive the disaster would face the consequences of a nuclear winter: all plant life would lose its ability to photosynthesize and die, herbivores would be the first to go extinct, followed by carnivores, disrupting the food chain and resulting in mass extinctions of species, including microorganisms.
Asteroid 2022 AP7 will not pose a significant threat to Earth in the near future.
Some may think that humanity has enough advanced technology to save itself. However, under the impact of a global disaster, even the most developed coastal cities would be submerged, with global air pollution, and the disruption of water, electricity, and transportation would render all modern production and living activities unsustainable.
A nuclear winter may not last long, and the Earth’s surface could see sunlight again after a few years or even a decade. However, Earth would no longer be the planet we know; original species would essentially be extinct, and the evolution of new life would take tens of thousands or even millions of years to develop again.
Fortunately, scientific monitoring has revealed that these Earth-threatening asteroids, including 2022 AP7, will not pose a significant threat to our planet in the near future. We still have time to unite and collaborate to advance science and jointly face potential disasters.
