Earth is under constant threat by thousands of asteroids.
1. What is an asteroid?
Asteroids are metallic, rocky bodies without atmospheres that orbit the Sun but are too small to be classified as planets. Known as "minor planets," thousands of asteroids congregate in the so-called main asteroid belt: a vast, doughnut-shaped ring located between the orbits of Mars and Jupiter.
Many asteroids, however, are classified as Near Earth Objects, meaning their orbit brings them in close proximity with our planet. While most of these asteroids do not pose a threat to us, thousands of them do.
As our planet swings through the solar system, it is important for us to study the orbits of existing and newly discovered potentially hazardous asteroids, in order to predict future collisions and hopefully prevent them.
2. Asteroids are all around us
Currently, over 500,000 asteroids have been identified and cataloged in our Solar System, and new ones are being discovered all of the time.
As of April 09, 2014, 10,906 Near-Earth Objects (NEO) have been discovered. Of these asteroids,1,466 have been classified as Potentially Hazardous Asteroids (PHAs). The orbits of these asteroids may cross our orbit, potentially colliding with the Earth, with catastrophic results.
3. Earth is getting hit all the time!
Every day, the Earth is bombarded with more than 100 tons of dust and sand-size particles. Many of the incoming particles are so small that they are destroyed in the Earth's atmosphere before they reach the ground. These particles are often seen as meteors or shooting stars.
Recent sensor data has shown that 26 explosions more powerful than a kiloton of TNT have been detected on Earth since 2001, all of which are due to asteroid impacts. This suggests that asteroid impacts are not rare, and are in fact are 3-10 times more common than previously thought.
According to former astronaut Ed Lu, the fact that none of the asteroid impacts detected was detected in advance is proof that "the only thing preventing a catastrophe from a 'city-killer'-sized asteroid is blind luck."
4. Past impacts have changed the Earth (not done)
Throughout the history of our planet, asteroid collisions have played a large part in shaping our geology, and may be responsible for global extinctions.
When large impacts occur, a crater is formed. Because of the dynamic geological nature of the Earth's surface, many craters are covered by forests or eroded by wind and rain. Despite this erosion, satellite imaging has identified craters left by past impacts.
5. It's only a matter of time (not done)
Of the cataloged potentially hazardous asteroids, those listed above will be approaching Earth this month. While the chances are small, a collision is still possible. In order to determine how much of a threat these asteroids pose, more research is needed.
6. What can you do? (not done)
Numerous government and private organizations are working to detect and catalog existing and new asteroids all the time, but the general public remains unaware of the threat of large asteroid impacts. By increasing public awareness, we hope to garner support for these projects, and help people understand how important it is.
If you are concerned about the potential threat of asteroid impact, and would like to do your part to address the risk, here are some actions you can take:
(insert list of organizational efforts, and actions that the average person can take to draw attention to the issue)