9 Biggest Killers In Space
9. Comets & Asteroids & Meteors - Oh My!
What is it?
Comets and asteroids and meteors (oh my!) are extremely commonplace objects throughout the universe. Most of these objects are moving at extremely high velocities, sometimes in excess of tens of thousands of miles an hour. They can be variable in size, from something as small as a grain of rice (or smaller) to the size of a mountain and beyond. Based on perception alone, you may presume the rice meteor would be harmless... that would be an incorrect assessment. A meteorite that size could destroy a space shuttle if it impacts it at 22,000 miles an hour; by breaching it's hull, passing through it, and causing the craft to decompress. The larger the meteorite, the more powerful the explosion obviously.
Meteorites as large as SUV's can wreak havoc equal to the size of a large ballistic missile across a small area, if they don't break apart entering our atmosphere first. Meteors, Comets, or Asteroids in motion that have more than a kilometer in diameter would cause an explosion many orders of magnitude greater than a 100 megaton nuclear bomb. roughly 500 times that of the Hiroshima bomb.
Anything larger than one kilometer in size striking the earth, is called an extinction level event, or "planetary killer" - although the planet won't explode, all (if not most) of the life on the planet will be destroyed by the resulting aftermath.
Is this common? Can I hide under a table to survive?
To answer this question just look up at the moon every night. Which essentially acts like a natural gravity shield, drawing objects toward itself and away from us. Despite this, Earth is still struck by all kinds of meteorites as well, most of which are usually broken up pieces from other celestial bodies. Fortunately, most of these objects are large pieces of ice that break up as they enter our atmosphere.
Most objects floating in space are caught by the gravity of another object, until it is effected by an outside force strong enough to liberate it from that pull. Impacts with other objects continue the process, material from that impact is thrown into space, and the process repeats.
Just outside of our solar system is a very healthy and massive "belt" of asteroids that are held together by the gravity of our star, illustrating what I said above. This is a process that occurs throughout the universe as dust, gas, and matter slowly settle closer together as systems form around its particular star. Ours is called the Kuiper belt, and many of the meteors we observe, as well as comets and other asteroids are pretty much playing "cosmic pinball" in this belt, if they weren't actually already born on this belt.
Has this happened before? Can it happen again?
There is a large asteroid with a trajectory that may bring it extremely close to earth. Enough to consider it a near-earth asteroid that has been in the news recently. Depending on it's trajectory during its first pass of our planet, we'll be able to determine if it will have a guaranteed impact trajectory in 2036. This asteroid has been named "Apophis", after an Egyptian Demon deified as the god of chaos, and is being watched closely to see if it passes through a goldilocks zone in 2029. This goldilocks zone is roughly half a mile wide, about 800 meters.
If it does, astrophysicists may predict it will have an impact with Earth 7 years later. This past January, however, it was determined that this asteroid would not make an impact. It's also stated in the Palermo Technical Impact Hazard Scale that there are 10 other threats higher up on the scale over Apophis. Apophis is roughly 325 meters in diameter, it's hypothesised that roughly once every 80,000 years an asteroid this size hits the Earth.
The quote above from the 1998 film, Armageddon, refers to the Yucatan peninsula meteor strike that devastating the earth and brought about the end of the dinosaurs. Using Google Earth, you can (partially) observe the massive asteroid crater in the Yucatan that was struck over 65 million years ago. While size indeed does matter, in this situation, we have one impact recorded on Earth that could be considered the mother of them all, in terms of objects impacting the planet. Except it's neither of these things, it's the size of a small planetoid...