Pluto - the last planet orbiting our sun is about to get a visit from the space probe " New Horizons " in the next few days. Pluto was only discovered as recently as 1930 and it is completely baffling to science because it appears to be a "dwarf " planet, or perhaps just a big space rock. It is only about a sixth of the diameter of our moon, but it has five of it's own moons and they orbit in a completely random pattern.
New Horizons was launched in January 2006 and has attained a speed of fourteen kilometres per second on it's journey into space, making it the fastest space probe ever. Until now, Pluto has been virtually ignored and we have concentrated more on Mars and distant galaxies, but this tiny sub planet has intrigued many people and we are finally getting to unmask it's secrets. The theory persists that when this galaxy was being formed poor old Pluto was probably work in progress - and nature ran out of building materials and gave up on the job, leaving it half finished.
It is what happens when New Horizons is finished taking photos of Pluto that the real mission begins. It will continue it's journey deeper into space and during 2017 until 2020 it will be investigating the Kuiper Belt - and that is something that many think poses the most danger to planet Earth.
Way out in space the Kuiper Belt is a mass of space debris of almost unimaginable proportions. We think it consists of rocks of various sizes drifting endlessly in orbit and in all probability these were left over when the planets were formed. This was the raw material that the nucleus gravity of each planet attracted as it coalesced it's solid core and formed a magnetic field - that attracted even more debris - and eventually created an atmosphere.
The problem is this mass of rock is quite capable of colliding and such collisions can change orbits. Our earth is a very tiny little target in a very big sky, but should one of these large space rocks come our way and slice into the earth it could send us the same way as the Dinosaurs - into extinction.
Judging by the craters on our moon, space collisions were a frequent oddity in the distant past and we still see small meteorites burning up in the night sky. We call them"shooting Stars " and they usually burn up before they reach this planet's surface, but more formidable hits can occur without warning.
In 1908 one of these devastated eight hundred square miles of forest in Tunguska in Russia's Siberia. It is estimated that a space rock coming to earth caused an explosion consistent with that of about forty nuclear bombs of Hiroshima size, and in February, 2013 a much smaller event happened over Chelyabinsk, a Russian city in the Ural mountains. The sonic boom broke thousands of windows and caused brick walls to topple, and dozens of people suffered injuries. Despite space research and facilities like the Hubble telescope, we had no advance warning that such a disaster was about to happen.
That is what worries some scientists. If a similar event to what happened in Tunguska in 2008 hit and demolished a major world city it could be thought to be a nuclear strike - and set off a raging nuclear war in response. We need to know a lot more about the Kuiper belt and how we can advance our early warning system - or possibly take action to nudge an oncoming rock onto a new course to miss Earth.
New Horizons will give us our first look at just what is in a massive circular orbit and with that knowledge we may be able to create a way of predicting future danger. We would all sleep a lot more soundly knowing that we have satellites keeping an eye on the Kuiper belt. The first task is to map it's extent - and that is about to happen !
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