Our Planet is Not as Safe as We Would Like it to Be! It can end anytime!
Here are Some Possible Astronomical Dangers to Earth in 2014
We are a small entity in a universe filled with mysteries and objects of all kinds floating and whizzing about. Looking at our often very ordinary lives, rooted in the present, focussing on ordinary matters, very rarely one gets time to think about what is happening in the great dark unknown out there. Very recently, the film Gravity sparked off the latent question hidden in my mind. Are we really at threat from outside forces?
And the answer to my research was, we are and can be very often at the threat of such forces. What are these which threaten our daily existence? These objects which are potential disasters to our very existence are described in scientific terms as Near Earth Objects. These are the objects, whose orbits (i.e. trajectories taken around the sun), under the influence of gravitational force of neighbouring planet, bring them into very close approach with the earth. NEOs are a part of the solar system. The known NEOs include:
- Near earth Asteroids
- Near earth Comets
Entities That Can Cause Astronomical Dangers
Asteroids form from asteroidal material, which are rocky material, entering the earth’s atmosphere from space. Do you know that almost 50, 000 tonnes of asteroidal fragments and debris enter the earth’s atmosphere, every year? Most of gets burnt up while coming through, while a few mange to the get through to the earth and may fall into oceans, or create craters on the surface of the earth.
Large sized pieces of rocks are called asteroids and smaller sized ones are called meteoroids. Meteroids can have two possible fates. Either they can burn up by streaking through the air as meters or they can fall to the earth as meteorites. Asteroids are believed to be the creation of debris created by the collision of giant asteroids as well as debris from the processes leading to the formation of the inner planets (mercury, venus, earthj and mars) and usually orbit in trajectories which lie between Mars and Jupiter.
An asteroid is termed a NEO when its path comes within 1.3 AU of the sun and thus within 0.3 AU o fthe earth’s orbit. The largest known of the NEA is 1036 Ganymede. A NEA can be a PHA when it comes near 0.05 AU of the earth’s orbit and the largest known PHA is 4179 Toutatis. 9446 NEAs with diameters less than 100 m are known of which 1260 are PHAs. NEA’s are divided into different groups based on their perihelion and aphelion distance and their semi major axes.
Can Comets Cause Astronomical Dangers?
Comets, on the other hand are composed of water and ice and dust and originally formed in the cold outer extremeties of the planetary system and were a leftover of the original process which led to the creation of the giant outer planets. Usually comets and asteroids are not threats to the earth. It is only when their size and their trajectories approach the earth, that they become a potential threat. Comets which fall under the NEO category are called Near Earth Comets and they have to have a distance of less than 1.3 AU from the earth as well as they have to be short period comets i.e. comets with a date of lesser than 200 years for appearance. Comets are more rare as compared to asteroids and last collisions was in 1908 in Siberia and the Shoemaker levy collision in 1994.
Comets frequently enter the atmosphere and fall. Those objects which fall within 1.3 u of the sun are considered to be NEOs. Not all NEOs are harmful. A sub category called Potentially Harmful Objects (PHO’s) is the subjects of intense attention by US’s NASA. These are the NEO’s whose diameter is at least 1 km wide and hence are potentially capable of causing huge damage to the earth, in the event of an collision.
They are characterised on the basis of their size and the distance of the intersection of the orbit with the earth. The risk which these objects cause to the earth is determined by their values as measure by the Torino or Palermo scale, which is a measure of the hazard caused.
There are roughly a 1000 NEOs’known which are PHO’s. So far the impacts of these objects have passed off without causing damage as their effects were restrained to the upper atmosphere. The impact which if they ever succeed in crossing this outer layer and entering the inner atmosphere can be as calamitous as that caused by a Hiroshima explosion. One of the last impacts, which caused drastic changes in the geology and biology of the earth was the one which occurred during the time of the dinosaurs and led to their extinction.
So How Safe Are We From Astronomical Dangers?
Encounters of these objects with the earth have been known to be associated with massive changes in the earth leading to astronomical dangers and hence scientists are constantly keeping an eye on them, recording their presence and tracking their movements, to be aware of any potential threats as well as to come up with measures, which may help in warding them off. NASA is keeping a tight watch on such NEOs. One such potential hazardous NEO whizzed past the earth in October 2013. It was named as 2013 TV135.
One new space object which may cause some impact is 2003 QQ47m which is 1.2 km wide and it may be in line for an impact in 2014 March, but scientists say there is not much chances of a catastrophic impact and predictions puts its risk at negligible. Recently, in March 2014, an asteroid DX110 went by the earth but it did not cause any incident even though it had gone extremely near the earth, approaching a distance of 217,000 miles from and reaching a speed of 33,000 miles per hour.
So here is to hoping that no impacts occur in the near future and we can enjoy our lives. Till then, we can keep one eye on what NASA is doing.
The file is in the public domain because it was solely created by NASA. NASA copyright policy states that “NASA material is not protected by copyright unless noted“.
http://en.wikipedia.org/wiki/Near-Earth_object http://m.teachastronomy.com/astropedia/article/The-Threat-from-Space http://edition.cnn.com/2013/10/18/tech/asteroid-near-pass http://www.space.com/22369-nasa-asteroid-threat-map.html http://www.techtimes.com/articles/4101/20140306/asteroid-2014-dx110-barely-misses-earth-flyby-serves-as-warning-of-possible-doomsday.htm