Welcome again to JJNN for Monday September 22nd, 2008. Today we will be talking about a comet.
What do you think about when you hear the word "comet"? For me it will always be Halley's Comet. I remember way back in 1986 when we could last see Halley's comet. Seeing that up in the sky was one of things that helped to spark my interest in nature and science.
Besides Halley's comet, there are a lot of comets out there. It is estimated that there over 3000 of them in our system. So, what exactly is a comet? Well basically it is a big dirty snowball that just happens to be in outer space. It is a lot of ice and rocks packed together and revolving around the sun. The thing that makes comets different from meteors is the fact that when the comets get close to the sun they have a coma, or tail. The tail is made from the sun vaporizing the comet's ice.
An interesting fact about a comet's tail is that it is always behind the comet. Sometimes the tale is in front of the comet. This is because the fact that the light from the sun pushes the gas from the comet away from it. This is probably a little hard to visualize because you never feel any pressure or force from the light of the sun, but in the vacuum of space the effect is huge. You can see this effect in an instrument/toy called a radiometer. You can see a video of one below.
So, what is all this about comets? Well this all comes from a news story that you can see here. It seems that two Japanese men named Itagaki and Kaneda saw a comet that has not been seen in over 100 years. The name of the comet 205P/Giacobini after its discoverer Michel Giacobini. Giacobini discovered the comet in 1896, but it was not seen on the way out of the solar system. Now that they have found the comet again we can track it and find out when it is going to make close passes with the Earth. That is a good thing.
Any way, it is now time for the word of the day. Today's word is 彗星(すいせい). It is pronounced suisei and means comet. The next time Halley's comet shows up it will be 2061. Hmmm... I wonder if there will be any other ones in the mean time because that is a long wait.
That's it for today. See you next time at JJNN.