Date:14 August 2013
This graphic shows the orbits of all the known Potentially Hazardous Asteroids (PHAs), numbering over 1 400 as of early 2013.
These are the asteroids considered hazardous because they are fairly large (at least 140 metres in size), and because they follow orbits that pass close to the Earth’s orbit (within 7,5 million kilometres).
Before you start to stress, know that being classified as a PHA does not mean that an asteroid will impact the Earth: none of these PHAs is a worrisome threat over the next hundred years. By continuing to observe and track these asteroids, their orbits can be refined and more precise predictions made of their future close approaches and impact probabilities.
Image credit and source: Nasa/JPL-Caltech