28 December 2006
The topic I’m going to discuss is ‘How old is Everything?’ and by saying ‘Everything’ I mean the ‘Universe’.
No one is sure of the age of the Universe, for no one knows how it began. Some say it’s the ‘Big Bang’ and some say it is the ‘Steady State’. In fact there are many more theories put forward to explain the origin of the Universe. But there is no proof for any of the theories but Big Bang has more evidences. The only way to find out when the Universe originated is by moving back in time. We are slowly going to move back in time and see if the Universe existed at that point of time. So let’s get to it.
Universe certainly existed 4000 years ago as we do have some proof of human civilizations in Earth. The best example is Indus Valley Civilization and Egyptian Civilization. But no one knows what had been before that. Discovery of Jurassic bones helped us move a little further. These bones were tested and they were found to have lived about 2000 million years ago. And so we can certainly say that Earth did exist 2000 million years ago.
Some of the rocks on this planet were tested by scientists and they found some of the oldest rocks on the surface of the Earth. These rocks were found to be billions of years old. The oldest rock ever found was nearly 4.5 billion years old. That could be the time when Earth had formed or much before that. We could not find anything older than that and so we assume that Earth is actually 4.5 billion years old. Some scientists believe that the Earth was formed along with the other members of the solar system including the Sun. And so they think that our Solar System is also 4.5 billion years old.
We have some how estimated the age of the Earth but what about the Universe? How can we find out the age of the Universe? We can not take any samples from other stars to tests its age. It is merely impossible to reach other stars. Are there any other methods to find the age of the stars without reaching it?
The age of some of the stars can be found by testing the magnitude or intensity or the brightness of the star. By calculating the magnitude of the star, the amount of Hydrogen that has been burnt in the star can be estimated. With the help of this we can estimate the time when the star will die and also when it was born. Using this method the scientists have found that Sun has a life span of 10 billion years will die in another 5 billion years. This is very close to our assumption of the age of the Earth. So the solar system must be around the age to 4.5 to 5 billion years. The magnitude of the stars from some of the Globular Clusters were calculated. A Globular Cluster is a collection of stars which are bound by gravity. Most of the stars in a globular cluster are old. The above picture shows the Globular Cluster M13 found in the constellation of Hercules. The age of the stars in various clusters was estimated and it was found that the oldest globular cluster was around 11 to 18 billion years old. This is the lowest limit of the age of the Universe we could ever estimate from the stars. Scientists are still trying out various experiments to extend this limit. As of now the age of the Universe is 11 to 18 billion years old.
This information has been acquired from the net. If you have any further doubt or any questions about this topic you can with pleasure mail me via email. You can also visit this website for further details.
8 October 2006
Hi friends... I have finally started a blog as requested by my friends. Since this is my first topic I have decided to share my knowledge on my favorite topic Astronomy, and in astronomy this is the topic which is discussed most in recent times.
As soon as you read the word 'Pluto' the questions that arises in your mind is ‘Why is Pluto removed from the list of planets? And is it a right decision?’ Some of us think it's crap but some think the decision is absolutely right. And I'm one of them. In fact I was expecting something like this to happen for a year as Pluto is different from other planets in many ways.
Before discussing on why Pluto was removed from the list of planets let us know some of the details about Pluto...
Pluto was discovered by Clyde W. Tombaugh in 1930. It was known as the smallest planet. Its distance from Sun is 5870 x 106 km. Its diameter is about 2,301 km. In fact Pluto is smaller than our satellite ‘Moon’ whose diameter is about 3,474 km. In 1978 Pluto was discovered with a satellite moving around it named Charon. And in 2003 astronomers discovered two more satellites moving around Pluto which was named Nix and Hydra.
Charon was discovered in 1978 by James Christy. Its diameter is about 1,207 km which is more than half the size of Pluto. Its mass is about 1/7th the mass of Pluto. It is the largest of the three satellites of Pluto. But since Pluto is no longer considered as a planet Charon is also not considered as a satellite. It was the discovery of Charon that began to change the fate of Pluto. The picture on the right is the artistic view of Charon from the surface of Pluto.
Since 2003 many more objects were discovered beyond the orbit of Neptune like Sedna, Quaoar, Orcus, Varuna, 2005 FY9, etc. and most of them were almost the same distance from Sun as Pluto. Some of them were almost the size of Pluto. In 2005 a new object was discovered ‘2003 UB313’ which was nicknamed as Xena and now officially called as Eris (in the left). Its diameter was found to be 2400 km which is slightly bigger than that of Pluto. And this discovery put an end to the journey of Pluto as a planet. The odds in the character of Pluto put together with these discoveries led to removal of Pluto from the list of planets.
Now let us see what are the odd characters found in Pluto.
1. Let us assume that the orbit of the Earth is horizontal. If we compare the inclination of the orbits of the other planets with that of Earth it is found that the planets other than Pluto were found to incline at an angle between 1° and 7°. But the inclination of Pluto was found to be 17.2°.
2. If we look at the orbit of Pluto it is found to draw within the orbit of Neptune for a time span of twenty years between 1979 and 1999 i.e. Pluto acts as the eighth planet for a time span of twenty years. This is clearly shown in the picture on the top. This type of behavior is not found in any other planet.
3. You can find huge gap between any two planets. For example the distance between Earth and Venus is 49.4 x 106 km and the distance between Earth and Mars is 78.3 x 106 km. All you find in between this gap is our satellite ‘Moon’. But as I said earlier many objects were discovered around the orbit of Pluto. These objects cannot be the satellites of Pluto as some of them were larger than Pluto itself.
4. A Satellite is an object that revolves around a planet just like a planet around a star. According to the Law of Gravitation the centre of gravity between a satellite and a planet should be approximately found in the centre of the planet which makes the satellite move around the planet in an orbit. If we compare the size of Pluto and Charon it is found that Charon is more than half the size of Pluto. By the Law of Gravitation the centre of gravity between these two masses will be approximately found in between the two objects. Which means that Charon does not revolve around Pluto but Pluto and Charon revolve around each other. Once again Pluto does not abide the rules of the Planet.
These are only few of the reasons that makes Pluto different from other planets and the astronomers had no choice but to remove Pluto from the list of Planets. All the objects which are beyond the orbit of Neptune are now considered as 'Trans-Neptunian Objects' (TNO) which include Pluto, Eris and other recently discovered objects. (The picture on the top is a comparison of the size of TNO's with that of the Earth and the Moon) The larger TNO's such as Pluto and Eris are considered as 'Dwarf Planets'. The eight largest TNO's are compared in the picture below.
And thus according to me removing Pluto from the list of Planets is the right decision. After all these there are still many unanswered questions put up about Pluto’s behavior and also about the Trans-Neptune Objects (TNO) which I believe may be found in the years to come.