Can Earthquake be predicted?

Earthquakes are terrible.It can devastate large areas and takes lives of millions .The earthquake that took in Equador in 1906 had the power of 300 hydrogen bomb.That which happened in China in 1976 had the power of 1000 hydrogen bombs.In this quake that occurred in Tang Shan 3 lakh people were perished.

The crust of the earth when subjected to forces breaks along fractures resulting in earthquakes .When the waves originating from the sight of the fracturing move upward and reach the surface ,the earth seams to shake,bringing about large scale destruction.

Man had attempted to study earthquakes from ancient times,1500 years ago a Chinese mathematician Chang Heng made a device to detect earthquakes.made of pendulum that could respond to the slightest movement of earth ,fixed to a huge 2m diameter vessel,we don't know how efficient this device had been.



READ MORE .

ScienceShot: Newfound Asteroid on Earth's Tail

Don't panic, but Earth has a celestial stalker. An asteroid discovered last fall moves in roughly the same orbit as Earth does. However, there's no need for a restraining order. Computer models indicate that for the foreseeable future, the object (denoted with an arrow in the photo) will stay at least 19 million kilometers away from our planet and, therefore, doesn't threaten a collision. Right now, the asteroid, dubbed 2010 SO16, is making one of its 

closest approaches to Earth, researchers at the Armagh Observatory in the United Kingdom report in April's Monthly Notices of the Royal Astronomical Society. Relative to Earth, the asteroid, which likely ranges between 200 meters and 400 meters across, moves in a horseshoe-shaped path that sometimes carries it to the far side of the sun. Simulations suggest that unlike the paths followed by three other known asteroids in such orbits, 2010 SO16's orbit has been stable for at least 250,000 years and will likely remain so for at least 200,000 years into the future. 

A long-lived horseshoe companion to the Earth

Apostolos A. Christou, David J. Asher

(Submitted on 31 Mar 2011)

We present a dynamical investigation of a newly found asteroid, 2010 SO16, and the discovery that it is a horseshoe companion of the Earth. The object's absolute magnitude (H=20.7) makes this the largest object of its type known to-date. By carrying out numerical integrations of dynamical clones, we find that (a) its status as a horseshoe is secure given the current accuracy of its ephemeris, and (b) the time spent in horseshoe libration with the Earth is several times 10^5 yr, two orders of magnitude longer than determined for other horseshoe asteroids of the Earth. Further, using a model based on Hill's approximation to the three-body problem, we show that, apart from the low eccentricity which prevents close encounters with other planets or the Earth itself, its stability can be attributed to the value of its Jacobi constant far from the regime that allows transitions into other coorbital modes or escape from the resonance altogether. We provide evidence that the eventual escape of the asteroid from horseshoe libration is caused by the action of planetary secular perturbations and the stochastic evolution of the eccentricity. The questions of its origin and the existence of as-yet-undiscovered co-orbital companions of the Earth are discussed.

Are the deserts expanding?

More than one fifth of the area of India is occupied by Thar Desert,Africa by Sahara Desert, China by Gobi  desert,South America By Atacama desert.The arid and semi arid lands constitute about two fifth of India where an estimated 200 million people are living.Deserts arid and semiarid regions of the world receive an average of less than 350 millimeter rain every year .These cover about 43 percent of earth's  land

surface.
 About 4500 years ago,the Harappan civilization flourished in regions now occupied by Thar desert.Rhinos and Elephants roamed in the forests that once grew there .large scale deforestation and climatic changes gradually converted the region into a desert. The Rajasthan desert is one of the  most densely populated deserts of  the world.The density of population is 48 persons per square kilometer. Rapid  increase in live stock population and increased cultivation  resulting in ploughing more  and more increased vulnerability of fertile soil if any  left to soil erosion

The deserts of the world show signs of expansion with time . Sahara desert is spreading southward as much as 50 km per year in some places . It has engulfed about 6500,000 square kilometers  of arable land during the last century.The situation is not different in South America ,West Asia,China and other places where desert occur.Many of the regions now occupied by deserts were once fertile.For about six centuries ,North Africa was one of the principal granaries of the ancient Roman empire.The sand dunes of Sahara covers the ruins of great cities once flourished there.