Online edition of Sunday Observer

The deadly tsunami that hit several Asian countries in December killing millions of people and causing heavy damages may have permanently altered Earth's rotation, according to US scientists.

In many international news reports, the US scientists have pointed out that this will shorten days by a fraction of a second and cause the planet to wobble on its axis.

Richard Gross, a geophysicist with NASA's Jet Propulsion Laboratory in California, theorised that a shift of mass toward the Earth's centre during the quake caused the planet to spin three micro-seconds (millionth of a second) faster and to tilt about an inch on its axis.

When one huge tectonic plate beneath the Indian Ocean was forced below the edge of another, it had the effect of making the Earth more compact and send it spinning faster.

The US scientist has said that although the changes predicted by his model probably are too minuscule to be detected by a global positioning satellite network that routinely measures changes in Earth's spin, the data may reveal a slight wobble.

The Earth's poles travel a circular path that normally varies by about 33 feet, therefore an added wobble of an inch is unlikely to cause long-term effects. According to Gross, the rotation is not very much precise and the Earth does slow down and change its rate of rotation.However, when those tiny variations accumulate, planetary scientists must add a 'leap second' to the end of a year.

Meanwhile some argue that although scientists have long theorised that changes on the Earth's surface such as tide and groundwater shifts and weather could affect its spin, until now they have not had precise measurements to prove it.

Has the pole shift begun? A pole shift is the movement of the entire crust and mantle of the Earth around the fixed axis of the gyroscopic core, like the entire skin of an orange coming loose so that it can move freely without being peeled.

We may be witnessing the beginning of the process that must ultimately lead to a pole shift of the Earth according to some scientists If this argument is true we can expect more such earthquakes spearing outward along the entire Andaman-Sumatra fault line and then replicating in the adjoining faults.

The Earth revolves around the Sun in a path in space which is called an orbit. The Earth rotates once in 24 hours bringing us day and night. It also revolves around the Sun once a year.The Earth rotates and revolves.

For centuries, time has been universally measured in terms of the rotation of the Earth. The second , the basic unit of time, was defined as 1/86,400 of a mean solar day or one complete rotation of the Earth on its axis. Scientists discovered, however, that the rotation of the Earth was not constant enough to serve as the basis of the time standard.

As a result, the second was redefined in 1967 in terms of the resonant frequency of the cesium atom - that is, the frequency at which this atom absorbs energy, 9,192,631,770 hertz (cycles per second).

The slight wobble of the outer Earth, known as precession, causes regional climate to change slowly on the Earth over thousands of years, with one full cycle lasting about 20,000 years.The rotation of the outer Earth has also slowed over time.

Recently, planetary scientists and geologists calculated that a day was six hours shorter 900 million years ago.

A space probe called Huygens plunged through the clouds of Saturn's mysterious moon Titan two days ago (January 14).

Scientists believe that conditions on Titan resemble those of the early Earth, but no spacecraft has ever peered beneath its thick clouds.

Huygens was scheduled to have just two hours to gather data and send the information back to Earth.Will this mission to a moon far, far away give us clues about the origins of life on our planet?

The Cassini spacecraft began a four-year study of Saturn. One of its first jobs was to deliver a very special Christmas present. On December 25, 2004 Cassini released a probe called Huygens.

Huygens is a European Space Agency mission to explore Saturn's mysterious moon Titan.

Hidden beneath the shrouds of Titan's thick atmosphere, we may find clues about how life began on Earth.

Titan is millions of kilometres away - how could it possibly give reliable evidence about life on Earth? It turns out that Titan's atmosphere is similar to the Earth's, billions of years ago. It's rich in nitrogen and contains carbon-based molecules that rain down on the surface. So it could hold clues about how the early Earth evolved.

The Huygens probe was scheduled to coast towards Titan and enter its atmosphere on January 14, 2005. During its two-hour fall through the atmosphere, it was to send back around a thousand images of the clouds and surface. Other instruments were scheduled to measure temperature, pressure and density.

But , there will not be much time to search Titan for evidence - just two hours to send messages back to the Cassini mother ship before it passes out of range.

That's assuming the probe survives its descent and the biting cold on Titan.Scientists are optimistic that whatever the surface is like, the probe stands a chance of surviving for at least a short time, so they can get some unique data back.