Why Pluto is not planet?

The recent declassification of Pluto from being a planet had made a lot of news. Many people ask me about Pluto ' Why astronomers discard Pluto from planet status?' Actually there was no specific definition for planet before this.

For thousands of years people have observed bright objects in the sky that moved in certain paths against the background of fixed stars, but very little was known about them. In fact the name "planet" given to these, comes from the Greek word for "wanderer". The five planets Mercury, Venus, Mars, Jupiter & Saturn could be seen with naked eye from the Earth & were known since antiquity. On the other hand, Uranus, Neptune & Pluto are objects discovered comparatively recently & were also classified as planets. But, today, hosts of newly discovered large objects in the outer regions of our solar system present a challenge to our definition of a "planet".

Making use of the currently available scientific information the International Astronomical Union (IAU), on August 24, 2006, agreed that a "planet" is defined as a celestial body that

1. is in orbit around the Sun.

2. has sufficient mass for its self gravity to overcome rigid body force so that it maintains a hydrostatic equilibrium (leading to nearly round shape). and

3. has cleared the neighbourhood around its orbit (meaning that there are no other bodies of comparable size other than its own satellites or those otherwise under its own gravitational influence.)

Pluto failed the third condition because it shares its orbital neighbourhood with Kuiper Belt objects such as the Plutinos. Moreover, Pluto & its satellite Charon have their center of gravity lying outside the Pluto. Hence it is not qualified to be a planet. But astronomers classified Pluto as "Dwarf Planet". A non satellite body fulfilling only the first two of criteria is classified as a "Dwarf Planet". Other two members of the dwarf planet category are Ceres & Eris.

Now the solar system consists of eight "planets". Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus & Neptune orbiting in that order of their distances around our star the Sun.

Some astronomers have their strong opinion for Pluto as a planet. I don't know whatever happened with Pluto is right or wrong. But, now at least we can classified Solar System objects with more scientific manner which necessary to understand our planetary system.

AK

Naked Eye Astronomy

One evening back at the end of 1996, my father came to home from work and said to me and my little sister "Let's go outside, I have something to show you." He took me and my sister to one small hill near to our home. From there he pointed towards the west horizon in the sky "That's it! Can you see that? It is a comet!" "A comet!" I had no idea what was comet? But that was my first look at the sky and from then I started looking upward.

I always wondered about the sky. I looked up at the huge number of stars and tried to find a constellation but get lost when I tried to connect the dots. I was eager to know about stars. Then once I found article in newspaper on current month sky with map, from that map I almost identified all major constellations of that month. Then by sky maps and star finder charts I have practiced naked eye astronomy for seven years.

Without any optical aid at all, you can observe a wide range of phenomenon in the sky. You can see the large dark areas on the Moon that are now known as to have resulted from large object crashing into it almost 4 billion years ago. So, easy are they to make out that they have given rise to legends about there being a man, or a hare in the Moon.

You can follow the nightly wondering of five of the planets, and from one place on the Earth or another you can spot the 88 constellations - the traditional star patterns. You can watch certain stars - the variables - alter in brightness over the course of days, week or months. You can see star clusters like the Pleiades in Taurus and gas clouds like Great Nebula in Orion. If the night is quit dark, the vast expanse of our own galaxy, the Milky Way, will be visible winding across the sky.

There are also artificial satellite to be seen, and showers of any meteors, If you go far enough north or south, can enjoy the fabulous fireworks display of the northern and southern lights.

When you start sky watching for the first time, it is best not to rush outdoors to begin learning the constellations as they are plotted on the star finder chart.

For beginner, the sky is a great spur of imagination. On your first night out, try connecting stars to make your own patterns and figures. Let your mind roam. It should be fun and you are unlikely to forget the position of the star in your personal constellations. By doing this, you will start sky watching in an entertaining and memorable way. And you will find the sky is really amazing with your eyes.

Amol Kate

Hello friends

Hello friends,
This is Amol Kate. I am amature astronomer. Currently working as a Science Communicator in the Vikram A. Sarabhai Community Science Center, Ahmedabad. Astronomy is not only my passion but also it is oxygen for me. So, I decide to open my desk in this web world to get connected with other astronomers and amatures from worldwide. Apart from this I want to share my thoughts and you can also share your thoughts with me on this subject. So, my friends you all are invited to my blogspot.
Friendly,
Amol Kate