Close Encounters with Asteroids and PHOs

On this day, January 13, 2013, an asteroid named Apophis will pass the Earth at a distance of just 9 million miles.   Apophis is about 275 meters in size. If it ever struck the Earth, it would release about ten times the energy of the largest hydrogen bomb ever detonated on Earth.   Looks like we'll get a free pass this time. The odds are less certain in 2036 when it shows up in our neighborhood again. At that time, the astrophysicists who keep watch on these celestial objects project that Apophis will pass within 100,000 miles of our planet. That's shaving it pretty close considering the Moon is 238,000 miles away.  Though the odds of Apophis colliding with Earth in 2036 are small, the possibility remains plausible enough to be unsettling.

 

About 65 million years ago, an asteroid six miles wide, hurtling through space at more than 20 miles a second, slammed into the ocean near Mexico's Yucatan peninsula.  The cloud of dirt, dust, and debris it threw into the atmosphere cut off the light from the sun for several years. If you've ever wondered what happened to the dinosaurs, this is the answer scientists provide.  Without sunlight, the food chain collapsed. If you didn't suffocate from all the dust and crap in the air, you froze to death or starved. Of course humans weren't around at that time. If we had been, we would've been wiped out right along with the other large animals.

Up until recently, no one was paying much attention to asteroids. Now we have scientists who specialize in searching out these objects with advanced, automated telescopes.

Asteroids are chunks of material leftover from the  formation of the solar system. There are likely between one and two million in number. Between 500 and  5,000 are thought to have the potential to be hazardous to the Earth. The ones that could do us harm are called potentially hazardous objects or PHOs. Fewer than 30 percent of those have been found.  

Not only do we have people looking for all those missing PHOs. We also have people who are developing ingenious ways to steer those PHOs that become a direct threat off in a harmless direction. 

It's an ugly thought, but we humans are increasingly making a mess of our own dominant time here on Earth. Getting struck by an asteroid would  be catastrophic.  It would wipe out most of us.  In a perverse way, it might also provide the best chance for nature and the biosphere to recover from the unprecedented stress caused by seven billion plus humans,  all seeking a piece of the planet's finite resources.

On a planetary scale, getting struck by an asteroid would hurt, probably a lot, but the Earth would survive and the biosphere would heal itself, just as it did 65 million years ago. 

Here is a link for NASA's  'Asteroid Watch' webpage...http://www.jpl.nasa.gov/asteroidwatch/

Here's a NASA video that reports on an asteroid scheduled to pass very close to Earth 1n February, 2013.   http://www.youtube.com/watch?v=GwidzVHvbGI&feature=player_embedded