Asteroids have fascinated humans for centuries, but they also pose a potential threat to life on Earth. The impact of a large asteroid could have catastrophic consequences, causing massive destruction and loss of life. As such, identifying and tracking potentially hazardous asteroids has become a priority for astronomers and space agencies around the world. In this article, we will explore some of the most potentially hazardous asteroids known to science and what is being done to protect the planet from their impact.
What are Potentially Hazardous Asteroids?
Potentially hazardous asteroids, or PHAs, are asteroids that come within 0.05 astronomical units (AU) of Earth’s orbit and are larger than 140 meters in diameter. These asteroids are considered potentially hazardous because of their size and proximity to Earth. They are also known as Near-Earth Objects (NEOs).
There are currently over 20,000 NEOs known to science, with new ones being discovered all the time. Of these, around 1,000 are classified as potentially hazardous asteroids. However, just because an asteroid is classified as potentially hazardous does not mean that it will necessarily impact Earth. The vast majority of these asteroids pose no threat to the planet, and astronomers are constantly monitoring their trajectories to ensure that any potential threats can be identified and dealt with.
Why are Asteroids a Potential Threat?
Asteroids are a potential threat to Earth because of their size and velocity. A large asteroid can cause massive destruction upon impact, equivalent to that of a nuclear bomb. The impact of an asteroid could trigger tsunamis, cause widespread fires, and even alter the Earth’s climate. The Chicxulub impactor, the asteroid that is believed to have caused the extinction of the dinosaurs, is estimated to have been around 10 to 15 kilometers in diameter. While an impact of this magnitude is unlikely to occur again in the near future, even smaller impacts could have serious consequences.
How are Potentially Hazardous Asteroids Detected and Tracked?
Astronomers use a variety of methods to detect and track potentially hazardous asteroids. One of the most effective methods is to use ground-based telescopes to search for NEOs. The telescopes scan the night sky, looking for any objects that move against the background stars. The brightness and motion of the object can be used to calculate its distance, speed, and trajectory.
Another method of detecting NEOs is to use spacecraft. NASA’s NEOWISE mission, for example, used an infrared telescope mounted on a spacecraft to scan the skies for asteroids. The advantage of using a spacecraft is that it can observe asteroids that are difficult or impossible to see from Earth.
Once an asteroid has been detected, astronomers track its trajectory using a combination of ground-based telescopes and spacecraft. The trajectory of the asteroid is calculated using complex mathematical models that take into account its size, shape, mass, and gravitational interactions with other objects in the solar system. By monitoring the asteroid’s trajectory over time, astronomers can predict its future path and determine whether it poses a potential threat to Earth.
What are Some Potentially Hazardous Asteroids?
As mentioned earlier, there are currently over 1,000 potentially hazardous asteroids known to science. Here are three examples:
Apophis
Apophis is an asteroid that was discovered in 2004. It is approximately 370 meters in diameter and is classified as a potentially hazardous asteroid. Apophis has an orbit that crosses Earth’s orbit, and there was some concern that it could collide with Earth in 2029. However, subsequent observations have ruled out a collision in 2029, although the asteroid will come within 31,000 kilometers of Earth, which is closer than some communication satellites.
Bennu
Bennu is an asteroid that is currently being studied by NASA ’s OSIRIS-REx spacecraft. It is approximately 500 meters in diameter and is classified as a potentially hazardous asteroid. Bennu has a small chance of impacting Earth in the late 22nd century, and it is being closely monitored by astronomers. In 2020, the OSIRIS-REx spacecraft collected a sample from Bennu’s surface, which will be returned to Earth in 2023 for further study.
2008 KV2
2008 KV2 is an asteroid that was discovered in 2008. It is approximately 500 meters in diameter and has an orbit that crosses Earth’s orbit. It is classified as a potentially hazardous asteroid, but it is not expected to come close to Earth for several centuries.
What is being done to Protect the Earth from Potentially Hazardous Asteroids?
Identifying and tracking potentially hazardous asteroids is an important first step in protecting the planet from their impact. However, there are also other measures that can be taken to mitigate the threat posed by these asteroids.
One approach is to deflect the asteroid away from Earth’s orbit. This can be done using a variety of methods, including the use of spacecraft to apply a gentle push to the asteroid over a long period of time. Another approach is to use a kinetic impactor, which involves colliding a spacecraft into the asteroid at high speed to alter its trajectory.
NASA is currently developing a mission called the Double Asteroid Redirection Test (DART), which will test the kinetic impactor approach. The mission involves launching a spacecraft to collide with a small moon orbiting the asteroid Didymos, with the goal of altering the moon’s orbit.
In addition to these technological solutions, there are also efforts underway to improve our understanding of the threat posed by potentially hazardous asteroids. The International Asteroid Warning Network (IAWN), for example, is a global network of scientists and astronomers who work together to detect and track potentially hazardous asteroids. The network also provides guidance on how to respond to any potential threats.
Potentially hazardous asteroids are a real and ongoing threat to life on Earth. While the likelihood of an asteroid impact is low, the potential consequences are so catastrophic that it is important to take the threat seriously. Astronomers and space agencies around the world are working to identify and track potentially hazardous asteroids, and to develop technologies to protect the planet from their impact. By working together and remaining vigilant, we can ensure that we are prepared for any potential threats from the skies.