NASA Says 500-Foot Wide Asteroid Approaching Earth Is 'Potentially Hazardous'

An asteroid estimated at between 70 and 160 meters (230 to 525 feet) in diameter will make a "close approach" to Earth next week, according to NASA. The rocky object, referred to as 2016 NF23, is traveling at around 20,000 miles per hour—faster than many rockets.

Data from the space agency's Earth Close Approaches website indicates that the Near Earth Object (NEO) will come nearest to our planet on August 29.

NEOs are any asteroid or comet whose orbits bring it into the inner solar system within about 121 million miles of the sun, and also within about 30 million miles of Earth's orbit.

If the orbit of an NEO at the time of its discovery is such that there is a (typically small) chance it will collide with Earth and cause significant damage, it is labeled "potentially hazardous," according to the Swinburne Astronomy Online Encyclopedia.

The asteroid, or other object, must have a minimum approach distance of less than 0.05 astronomical units or roughly 4.6 million miles to be classified as such. At its closest approach, 2016 NF23, for example, will be approximately 3.1 million miles (or 0.033 astronomical units) away from Earth. Fortunately, this means there is no danger of a strike.

If an asteroid the size of 2016 NF23 did crash into our planet it would cause significant damage on the scale of entire countries. A strike involving a larger asteroid greater than a kilometer (0.62 miles) in diameter would have global consequences if it crashed into Earth.

Read more: NASA is approaching the asteroid Bennu, one of the most 'hazardous' objects that might hit Earth

Aside from the massive destruction resulting from the initial impact, the global climate would be affected, leading to widespread crop failures and loss of life, among other effects.

Once potentially hazardous asteroids or other objects, such as comets, are discovered, they are monitored continually by observatories around the world. Over time, their orbits may be disrupted through gravitational interactions with other planets or bodies, increasing or decreasing the risk of a collision, according to the Swinburne Astronomy Online Encyclopedia.

Stock image of an asteroid. One of these rocky Near Earth Objects will come nearest to Earth on August 29. iStock

But even though the orbits of "potentially hazardous asteroids" are uncertain,"it is possible to estimate the size of these uncertainties and place corresponding limits on close-approach distance and time," according to NASA.

In total, the number of known NEOs exceeds 18,000. Researchers have detected around 90 percent of those larger than a kilometer in size, none of which are predicted to collide with Earth.There are, however, thought to be many NEOs smaller than this that are currently unaccounted for.