Potentially Hazardous Asteroids

I’ve decided to write this blog about Potentially Hazardous Asteroids (PHAs). They are asteroids that come threateningly close to Earth, 0.05 AU or less into Earth’s orbit. According to Near Earth Object Program in order for an asteroid to be considered a PHA it also has to have an absolute magnitude (H) or 22.0 or less, as well as coming 0.05 AU or less close to the Earth. Currently there are 906 known PHAs and by monitoring their orbits we can make more accurate predictions on the threat of an impact on Earth.

The smaller the magnitude of a PHA the larger the diameter. Example: a 3.0 magnitude (H) asteroid has a diameter of 670 km - 1490 km, while a 30.0 magnitude has a diameter of 3m – 6m!

The next PHA coming close to Earth is Apophis asteroid number 99942. It will approach the Earth closely in 2029. From collected data in 2005 enough information was given that the asteroid will not impact the Earth, merely coming really close.

Potentially Hazardous Asteroids can be quite accurately tracked because of their predictable orbits, and in my opinion knowing where they are is important.