# Asteroids and Earth: Should We Be Concerned About Impacts?
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Chapter 1: The Asteroid Dilemma
Every few weeks, a new alarming headline emerges, often reading something like, “Massive and Potentially Dangerous Asteroid Approaching Earth.” Each time, my heart races, and I feel a rush of anxiety, prompting me to click the link. Yet, time and again, these concerns turn out to be exaggerated. It's essential to understand the genuine risks involved, particularly since Earth has experienced impacts in the past and will likely face them again. So, when should we truly be alarmed?
Understanding Near-Earth Objects
Near-Earth Objects (NEOs) refer to a range of small celestial bodies, including comets, asteroids, and meteoroids, that come close to our planet. In its formative years, Earth faced intense bombardment from space debris, which created features like the moon’s craters and contributed to mass extinctions 66 million years ago. Most of the asteroids we encounter today are remnants from the solar system's formation roughly 4.6 billion years ago.
Image Credit: NASA/Goddard/University of Arizona/Lockheed Martin (Usage Policy)
On average, an object measuring just over half a mile in length collides with Earth every 500,000 years. Asteroids around 13 feet long enter our atmosphere approximately once a year, but many of these smaller objects burn up before reaching the surface. The only recorded modern impact that caused human injuries occurred in 2013 when the Chelyabinsk Meteor exploded in Russia with the equivalent force of 40 atomic bombs.
Any NEO larger than 460 feet that crosses Earth's orbit is categorized as potentially hazardous. Reports from the World Economic Forum indicate that over 2,000 such objects have been detected in proximity to Earth. However, the most perilous are those that remain undetected. According to Space.com, there may be as many as 17,000 or more concealed NEOs in our cosmic neighborhood.
One asteroid, Apophis, long regarded as a major threat to Earth, will pass within 20,000 miles of our planet—closer than some satellites. Fortunately, scientists have recently removed Apophis from the “risk list” after successfully tracking and predicting its trajectory. NASA currently does not foresee any potential impact from Apophis or other asteroids for at least a century.
Image Credits: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill (Usage Policy)
Mitigation Strategies for Impact Safety
In the unlikely event of an asteroid impact, what measures can we take to safeguard ourselves? For the most part, there is little we need to do. Our planet has a protective ally in Jupiter, which acts like a "vacuum cleaner of the sky," deflecting NEOs away from Earth and its immediate neighbors. However, it cannot eliminate all risks and has been known to occasionally redirect objects toward the inner planets of the solar system.
NASA employs various ground-based telescopes and the NEOWISE infrared space telescope to monitor asteroids and anticipate their potential intersections with Earth’s orbit. Additionally, the Minor Planet Center maintains a comprehensive database of NEOs, documenting their orbits and announcing new discoveries.
Image credits: NASA’s Goddard Space Flight Center-NASA/Goddard/University of Arizona (Usage Policy)
At the Center for Near Earth Objects (CNEOs), scientists simulate potential impact scenarios to enhance disaster preparedness and conduct long-term analyses of nearby NEOs to assess their threat levels. NASA emphasizes that “an asteroid impact is the only natural disaster we might be able to prevent.” The agency has devised several strategies to achieve this, including:
- Gravity Tractor: A spacecraft modifies an asteroid's trajectory using gravitational attraction while maintaining a steady position relative to the object.
- Kinetic Impactor: A spacecraft collides with an asteroid in hopes of altering its course. This method is set to be tested in 2022 through the DART mission.
- Nuclear Explosion: A nuclear device detonated near an asteroid could redirect it by unleashing radiated energy.
Regardless of whether an impact is anticipated next year or a century from now, a proactive strategy is undoubtedly the best course of action, and NASA takes this responsibility seriously. Researchers are continuously working to innovate and strategize to keep our planet safe. Thus, there is no immediate cause for alarm.
This video discusses the warning from NASA regarding an asteroid expected to approach Earth this month, providing insights into the potential risks and realities of such events.
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