Everything You Wanted To Know About Asteroids

 With the recent asteroid pass over Earth, and the Russian meteor that exploded last week, I thought this would be a perfect time to have a bit of a discussion about asteroids.

Asteroid DA 14, which passed the Earth at a distance of about 17,000 miles February 15th.

Asteroid DA 14, which passed the Earth February 15th.

What are Asteroids?- An asteroid is basically a rock that floats in space.  They do not have any atmosphere, and are too small to be considered plaents. Most asteroids are part of a vast belt between Mars and Jupiter nearly 60 miles wide. According to Space.com, the belt has over 750,000 asteroids floating within.  Asteroids are generally made of rock, but they often contain gasses like Nitrogen and Hydrogen at their cores. NASA has 3 different classifications of asteroids- Class C, (which are mostly made of Carbon), are the most common, and appear gray, like DA14 and the Russian meteor.

The biggest asteroid ever seen is technically also a dwarf planet named Ceres, discovered in 1801. It is nearly 600 miles across and orbits around Mars and Jupiter.

A view of the Orion Nebula in the constellation of Orion. Those three streaks are meteors that I captured as they came shooting across the screen.

A view of the Orion Nebula in the constellation of Orion. Those three streaks are meteors that I captured as they came shooting across the screen.

Difference between Asteroid and Meteors. An asteroid is an asteroid, asl long as it does not pass through the Earth’s atmosphere, then we re-name the object a meteor, commonly known as a “shooting star.” Like fireworks, meteors burn with a variety of different colors, depending on the chemical composition of the metals of which they are made.

Once the meteor finally hits the Earth’s surface, it is re-classified again as a meteorite. Over 10 tons of meteors hit the Earth every day, but by the time they get through the mile-long journey through the Earth’s atmosphere, the meteors are reduced to dusty grains no bigger than the sand you find on the beach.

 A Meteor Shower occurs when lots of tiny pieces of rock go through the Earth’s atmosphere at once and burn up in bright streaks. These streaks are often the debris from a comet and occur at regular intervals throughout the year. The next one to occur in 2013 is the Lyrid Meteor Shower, the debris from Comet Thatcher; the shower is scheduled to appear on April 22nd.
Meteor Crater Arizona, site of a meteor impact over 500 million years ago!

Meteor Crater Arizona, site of a meteor impact over 500 million years ago!

Meteors have crashed into the Earth, Moon, and other planets since the beginning of time. Over three billion years ago, asteroids containing the carbon and oxygen like outer-space care packages, hit the Earth, causing the planet’s atmosphere to slowly change from mostly methane gas, to its breathable state that supports living beings. On the Moon, asteroid collisions formed the craters that we see when we look at the Moon through telescopes. Some even speculate that the Moon might have been formed with an asteroid crashed into the Earth, sending molten rock into space that eventually cooled down to form the current Moon. As you can see in the picture on the left, meteors do still occasionally hit the Earth, although most of them burn up in the Earth’s atmosphere

Have there been any recent close calls with asteroids besides the Russian meteor? You may know that the same night as the Russian meteor, a much larger asteroid called DA 14 flew harmlessly by the Earth. Last year some speculated that DA14 would be eventually strike the Earth, and bring about the fabled 2012 Mayan apocalypse. However, these are only the most famous recent close calls. According to the International Astronomy Union (IAU), over 900 Near Earth Asteroids have been observed since 2011. A NEA is defined as an asteroid that passes within 1.3 Astronomical Units, or the distance between the Earth and the Sun. One of the most frightening examples occurred over the Mediterranean Sea. Space and Defense agencies warned that a sea impact could actually be worse than a land impact, as it could create massive tidal waves that could drown the whole country. Fortunately the meteor disintegrated before hitting the planet. General Simon Worden delivered a speech where he expressed relief that the asteroid didn’t impact, or even worse, be mistaken by mediterranean countries as hostile fire, and therefore an act of war:

The event of this June caused little or no notice as far as we can tell. But had it occurred at the same latitude, but a few hours earlier, the result on human affairs might have been much worse. Imagine that the bright flash accompanied by a damaging shock wave had occurred over Delhi, India or Islamabad, Pakistan? Neither of those nations have the sophisticated sensors we do that can determine the difference between a natural NEO impact and a nuclear detonation. The resulting panic in the nuclear-armed and hair-trigger militaries there could have been the spark that would have ignited the nuclear horror we’d avoided for over a half-century. This situation alone should be sufficient to get the world to take notice of the threat of asteroid impact- Gen. Worden, quoted in SpaceRef.com.

How are scientists studying these asteroids? Scientists all over the globe are keeping close watch for Near Earth Asteroids with ground based telescopes and space probes. In fact, the Canadian Space Agency just launched a new satellite early last week designed to track asteroids and other Near Earth Objects: http://www.asc-csa.gc.ca/eng/satellites/neossat/default.asp

Not to be outdone, NASA is also developing the NEAR program, and Russia has the Planetary Defense League. Plans are also underway for a new system of telescopes designed to give everyone on Earth a week’s head’s up for an imminent asteroid impact called the Asteroid Terrestrial-impact Last Alert System (ATLAS) to be ready in 2015.

Why didn’t scientists predict the Russian meteor? Simply put, the meteor, (which has been described by NASA as a “little asteroid”), was too small for the space agencies to detect.

Could an asteroid destroy the Earth? To be honest- yes. Although the planet Jupiter, with its massive size helps considerably in deflecting asteroids, an asteroid could impact the Earth at any moment. If the asteroid is of sufficient size, its impact could send dust into the atmosphere, blotting out the Sun. This would effectively kill all life on Earth. We know this is true because it’s exactly what killed the dinosaurs over 65 million years ago. This is why studying asteroids is so important.

How to prepare for an asteroid apocalypse– Discovery Magazine.com has provided a list of 10 ways to stop an asteroid for fun, which I have linked to here. My personal favorite is the plan to paint the asteroid with light-deflecting paint, to hopefully use solar radiation to push it away.

Well, hope that satisfies your craving for outer-space knowledge. As you know, although asteroids and meteors are fairly common, they only rarely hit the Earth. With any luck, our planet will be safe from a catastrophe for a long, long time.

Happy Stargazing!

Paul

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About astronut1

I describe myself as a "historian, lore-ean, and motormouth." I consider myself a student of the humanities, as well as a teacher. My motto is that if I can learn it, anyone can.

Posted on March 2, 2013, in Astronomy News, Space Exploration and tagged , , , , , , , , , , , , , , , , . Bookmark the permalink. Leave a comment.

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