NASA has just released a new Potentially Hazardous Asteroid (PHA) survey that has resulted in a higher number of PHA's than was previously thought. PHA's are asteroids that have the potential to pose a threat to our planet due to how close they will come tour home world.
As stated by NASA in its press release:
Observations from NASA's Wide-field Infrared Survey Explorer (WISE) have led to the best assessment yet of our solar system's population of potentially hazardous asteroids. Also known as "PHAs," these asteroids have orbits that come within five million miles (about eight million kilometers) of Earth, and they are big enough to survive passing through Earth's atmosphere and cause damage on a regional, or greater, scale.
The asteroid-hunting portion of the WISE mission, called NEOWISE, sampled 107 PHAs to make predictions about the population as a whole. Findings indicate there are roughly 4,700 PHAs, plus or minus 1,500, with diameters larger than 330 feet (about 100 meters). So far, an estimated 20 to 30 percent of these objects have been found.
|In this simulated view of the near-Earth asteroid population, potentially hazardous asteroids (PHAs) are denoted in orange. Less dangerous near-Earth asteroids are blue. Earth's orbit is green. NASA|
The good news is that we are devoting resources to look for these potential killer rocks. With their size, if one of these PHA's were to hit us, it would at the very least, and in all likelihood be a city killer. We get atmospheric "hits" every month that are on the order of tens of kiloton (thousand tons of TNT) energy but they are fortunately high up and do no damage.
The bottom-line in all of this is that it is only a matter of "when", not "if", that our planet - and us - face an incoming asteroid, or comet, that has our name on it. Planetary defense and emergency response can only begin once we know what we are up against....knowledge is power to react and we will all be safer as a result.
Read More About It: http://science.nasa.gov/science-news/science-at-nasa/2012/16may_pha/
Sky Guy in VA