Meteors

Meteors

So, I don't know about you, but there are some things we don't even think about in our daily life, even when we know they exist and we might not have the faint idea that they could be dangerous.  I'm talking about meteors.  When we stop and look at the sky at night time and we see the stars we can't help to think how grand it is, and often times we dismiss the fact that we are exposed to being wiped out just like the dinosaurs.  It turns out that last month a meteor passed so close to earth that NASA was a bit concern.  Whaaat?... and no one told me.  I guess if that meteor had hit Earth maybe we've all been gone!! But, not this time, we're still here.  I guess I have to make time to watch the news every now and then to see what's going on.  I don't want to be like the dinosaurs and don't know what hit them.  Lets see what happens in 19 years when this meteor is scheduled to come back... I better tell my grandkids!!

 

Let me tell you some things about meteors.  Many of you may know all this but just in case.

 

 

According to Geology.com:

Ever since the Earth formed about 4.5 billion years ago, it has been bombarded with rocks from space.  Each year about 50,000 tons of asteroidal material enters the Earth's atmosphere.  Most of it burns up high in the ionosphere due to friction with air.  But a few rocks get through.

 

Large space rocks are called asteroids, and small ones are called meteoroids.  When they streak through the atmosphere they are called meteors, or "shooting stars" if the reach the ground they are called meteorites.

 

What are they made out of?

Most asteroids and meteorites are composed of rocks similar to those on Earth - olivine, pyroxene, etc.  This are called "chondrites" or "stones".  Stones that are rich in carbon are called "carbonaceous chondrites" and some of these contain amino acids, the building blocks of life.  Some astronomers believe that life on Earth was seeded by comets and meteorites.

 

Comets are much less common than asteroids, but one in while they strike the Earth too.  Comets are irregular balls of dusty ice- "dirty snowballs"- a few km across.  They are largely inert except when they are heated as they pass near the sun an release gas and dust to form their tails.

 

How often do they hit the Earth?

Every day! but only rarely does one reach the ground.  Depending on their composition, meteors smaller than about 10 m in diameter do not survive their passage through the atmosphere.  A smaller iron would probably make it through but it would take a larger comet to survive our atmosphere.

 

Recent News

According to CNN:

 

One of the most dangerous asteroids or record zipped close by Earth last month.  It made headlines on Thursday, when reports said that there's a chance it could strike our planet in less than 20 years.  Such a collision could unleash a force as powerful as a couple of thousand atomic bombs.

 

But NASA was quick to calm nerves and point our some very good news.  The most dangerous known asteroids don't really pose much of a threat.  And there are very few of them.

 

According to NASA:

Newly discovered asteroid 2013 TV135 made close approach to Earth on Sept. 16 when it came within about 4.2 million miles (6.7 million kilometers).  The asteroid is initially estimated to be about 1,300 feet (400 meters) in size and its orbit carries it as far out as about three quarters of the distance to Jupiter's orbit and as close to the sun as the Earth's orbit.  It was discovered on October 8, 2013, by astronomers working at the Crimean Astrophysical Observatory in the Ukraine.  As Oct. 14, asteroid 2013 TV 135 is one of 10,332 Near-Earth objects that have been discovered.

 

With only a week of observation for an orbital period that span almost 4 years its future orbital path is still quite uncertain, but this asteroid could be back in the Earth's neighborhood in 2032.  However, the Near-Earth Program Office states the probability this asteroid could then impact Earth is only 1-in 63,000.  The object should be easily observable in the coming months and once additional observations are provide to the Minor Planet Center in Cambridge Massachusetts, the initial orbit calculations will be improved an the  most likely result will be a dramatic reduction, or complete elimination, of any risk of Earth impact.

 

"To put it in another way, that puts the current probability of no impact in 2032 at about 99.998 percent," said Don Yeomans, manager of NASA's Near Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "This is a relatively new discovery.  With more observations, I fully expect we will be able to significantly reduce, or rule out entirely, any impact probability for the foreseeable future."

 

NASA detects, tracks and characterizes asteroids and comets passing close to Earth using both ground- and space-based telescopes.  The Near Earth Object Observation Program, commonly called "Spaceguard." discovers these objects, characterizes a subset of them, and determines their orbits to determine if any could be potentially hazardous to our planet.

 

Wow! how interesting.  This leaves me with a sense of security, to know that someone is really watching out for Earth. I guess my trouble will be finding out when something is going to happen. Many people find things out on FaceBook (I don't have a Face Book!.... Vero, you better let me know if something is going on!). I should start watching the news once in a while.

Ok, this is it for now folks! I leave you with nice pictures of comets and meteors.

B :)