Galaxies and Planets

By: Kenneth McCormick

It is getting to the point where planets are being found everywhere. Fifty here, fifty there, well maybe I am exaggerating a little, but there are a lot of planets out there. Now that we know for sure that planets exist outside our own solar system, maybe we should stop counting the ones that we find. Why do I say this? Our galaxy is only one of billions, or even more. It contains over 100,000,000,000 stars. If only one star in three has planets around it and lets say the average amount of planets is 4, we are looking at a heck of a lot of planets my friends. That is roughly 133,333,333,333 planets in only our own galaxy. If only one planet of these in 1,000 has life, we are looking at 13,333,333 planets containing life. If only 1 in 1,000 of these has intelligent life, we are look at 13,333 planets in our galaxy that contain intelligent life. Now you know why we are searching for signals from planets with intelligent life, it is because the numbers favor the chances of it being there. Our world can't be that special that we are the only intelligent beings in the galaxy. It would be very closed minded of us to believe this. Even if we take the bible as a literal interpretation of God's word, I don't think there is anything in there that prohibits life in other places besides Earth. Maybe I will receive an argument on this, but this is what I believe.

The Andromeda galaxy is our neighbor galaxy. It is classified as M31. The M stands for Messier Object. Charles Messier was a French astronomer that lived from 1730 to 1817. He complied a list of objects that were difficult to tell from comets. Of course the telescopes then were not as good as the ones today and today this isn't a problem. There are 110 of these objects. Andromeda is a larger galaxy than our own. It is pretty near us in cosmic terms and is headed for a collision with the Milky Way. Don't worry though, it will take about 4 billion years before this happens. Even when it does happen there is not much chance of being smashed into. The stars are just too far apart. NASA describes it this way, picture two grains of sand separated by a football field. That is about the distance of the stars from each other in each galaxy. When the two galaxies do meet, they will pass into each other at the speed of about 1,000,000 mph, Ouch! Some day the Milky Way and Andromeda galaxies will be one. The main problem with the two galaxies passing into each other is the gas and debris that each contain. Recent findings indicate that the Andromeda Galaxy contains over a trillion stars, which is far more than the Milky Way, but here is the kicker, they have also found that the Milky Way is more massive, due to more dark matter being present. Dark matter is the matter that we can't see. It is estimated that 90% of the universe is made of it. Because of all this dark matter in our own galaxy, it would have been interesting to see how this effects the collision between the two galaxies.

Forgetting the collision for a second, the potential for planets in the Andromeda Galaxy is even far greater than our own, because of the number of stars in that galaxy. Scientists believe that the same physics is in effect in all galaxies and throughout the universe. I wonder if this could be a wrong assumption, even in small ways? For example, what if there was a planet where things didn't work quite the same. For example, we are used to seeing things fall down in a straight line. What if there was a planet where there was similar gravity to our own, but for some unknown reason, things that fell hit the planet on an angle? With so many different planets and so many different compositions, things could be quite different than what we are used to, even if it didn't violate the physical laws. Would it be possible to find a galaxy that had no planets or that had at least 5 or 6 planets for every star? These are extreme cases, but you just can't rule anything out when you are talking about the unknown.

Our own galaxy has satellite galaxies circling around it, like planets orbiting the sun. Two of these galaxies are the Small Magellanic Cloud and the Large Magellanic Cloud. The nearest galaxy to our own was thought to be the Large Magellanic Cloud, at 163,000 light years away. In 1994 it was discovered that the he Sagittarius Dwarf Elliptical Galaxy was closer at only about 80,000 light years. The Magellanic Cloud galaxy is like a blob of stars. It can only be seen in the southern hemisphere. This galaxy is disintegrating because we are absorbing it. The gradational tug of war between this galaxy and our own is creating thousands of star clusters between the two. The third closest galaxy to us, at about 200,000 light years, is the Small Magellanic Cloud, a dwarf galaxy. Again this galaxy is being absorbed by our galaxy. Gas is being created by dying stars and so are star clusters, as they are being pulled away from the Small Magellanic Cloud. There is also a debris trail that stretches from both of these galaxies into our own. This is another galaxy that can only be seen from the southern hemisphere. Thanks to these two galaxies, our own is getting bigger. Both of the Magellanic Cloud galaxies are considered to be primitive and neither is said to have as many heavy elements as our own galaxy. The chances of finding planets with life in the two Magellanic Cloud galaxies are much slimmer than in our own or the Andromeda galaxy. This is because there are a lot of very young stars in them, some being as young as only twelve million years old. This doesn't give much time, if any, for planetary development.

Our Milky Way is about 90,000 light years in diameter and has a circumference of about 270,000 light years. It is disk shaped and is about 2,400 light years thick. None of these figures are exact and can be off by as much as 50,000 light years, no one knows for sure. Our galaxy is part of a group of galaxies known as the local group. This group is in itself part of the Virgo Supercluster. Other dwarf galaxies that orbit our Milky Way are Canis Major, Sagittarius, Ursa Minor, Sculptor, Sextans, Fomax and Leo. Some are so small that they are only 500 light years across. These tiny galaxies would be Carina, Draco and Leo II, all dwarfs. It is thought that there might be more of these galaxies orbiting us that have much less mass and therefore are going undetected for the moment. It is felt that they might be mostly gas and dust. There is a ripple effect at the southern edge of our galaxy and this is thought to be caused by the Magellanic Clouds as they orbit us. The speed of the approaching Andromeda Galaxy is about 100 to 140 kilometers per second. That is roughly 67 to 93 miles per second. No one is quite sure how fast our galaxy is traveling. There have been estimates that range form 100 km to 1,000 km. per second. That is somewhere between 67 to to 667 miles per second and even this might be wrong.

Some of the recently found planets from outside our solar system include one that was discovered orbiting a star that was considered quite normal. The planet is about 5.5 times the size of the Earth. It is further away from its sun than we are from ours. The star it orbits is 28,000 light years away and the planet is thought to be rocky. The star it orbits is a red dwarf. That means it is about 50 times less powerful than our sun, but is the most common type of star in the universe. Some Earth sized planets have been detected, but these were only orbiting dying neutron stars. A neutron star is a star that comes from a supernova explosion. It is VERY dense. You are talking about a star that is only about 10 km(about 6.5 miles) in radius, yet has a mass about 1.5 times that of our sun, which has a radius of 695,000 km (about 463,333 miles). It is believed that any planet orbiting a sun of this type MUST be a dead world. Another planet was found at a distance of about 20 light years. It is rotating around a red sun that is about 1.5 times the size of our sun. The planet is considered to be very Earth like and its discovery was announced in April, 2007 by a team of European astronomers. There is evidence to suggest oceans. The diameter is 12,000 miles and its mass is 5 times that of Earth. Some scientists are already saying that this planet might just have the best chance for life so far. I believe that this statement is far too premature. The planet is located in Libra.

Have you ever wondered why we are finding planets that are usually huge? The answer is simple, it is hard to find planets because their suns block out their light. The bigger the planet the more light it gives off and the easier it is to find, not that finding planets is easy. Will we find a planet that has life on it? It seems that the universe has a surprise for us. That surprise is that there are many planets out there and many are similar to our own world. There may be millions and billions of societies waiting for us, or trying to avoid us, whatever the case may be.

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