Our Universe Things in the universe are really far from each other, of course this view is by a 21st century person. Maybe someone alive in the 30th century will think that a trip inside our Solar System will be like a subway ride is today. Looking at our Solar System, we see a sun surrounded by planets. We believe there are 9 planets, but there could be one or two more that haven't been discovered yet. So far, we have discovered 193 satellites going around the planets. Besides these planets and moons, the Solar System contains comets and asteroids. As the planets go around the sun, they are all in the same plane and orbit in the same direction. It sort of makes you wonder why, doesn't it? If life was to exist somewhere other than Earth, but in our Solar System, the places that have the best prospects for it are: Mars is the most Earth like and a planet, Europa, a moon of the planet Jupiter which might have water, Titan, a moon of Saturn might have the chemistry, Enceladus another moon of the planet Saturn may have water and Io another moon of Jupiter might have the chemistry and a favorable temperature. The flaw in this view may be the fact that since we are basing our assumptions using life on Earth as a criteria, we could be wrong, life might exist in places where we never thought possible and may be a completely different type of life than what we are looking for. Wouldn’t it be strange if the type of life on earth was different from most other life anywhere else? Our Solar System is a place where our star the Sun, controls bodies by use of its gravitational attraction. Any body that is controlled this way is part of this system. There are many different definitions of a Solar System, the one I used seems to be the most accurate. The planet that is the furthest away from the Sun, at times, is Pluto, which many astronomers no longer consider a planet. I say at times because Neptune sometimes is further. Right now, some scientists are saying Pluto isn't a planet and the classification was wrong, but while this fact is in dispute, I will still call it a planet. The distance from the sun to Pluto is about 5,946,000,000 kilometers or about 3,567,600,000 miles using a rough calculation of 3/5 times kilometers. The outer boundary of the solar system is considered the Heliopause, that is the area where the Sun's solar wind is stopped by the interstellar medium. It is believed that this region starts at somewhere between 8 to 14 billion miles from the Sun. The Voyager space probes launched in 1977 have finally passed the Heliopause. The furthermost voyager is about 13.5 billion miles away. It is traveling at a speed of about 3.6 AU per year. An AU is an astronomical unit and it equals the distance from the Sun to the Earth or about 93,000,000 miles. Voyager 2 is a little over 11 billion miles away. As we move out of the Solar System, we discover the distance to the closest star is 4.2 light years. Way too far for us to travel there using our current technology. The star is Proxima Centauri. There are a couple of more stars almost as close. Close stars are Alpha Centauri A, at 4.3 light years distant and at the same distance, Rigil Kentaurus, and Alpha Centauri B. There are 8 more stars that are under 10 light years away. No doubt these will be the first star systems we travel to, if we ever master space warp. These stars are only a small part of the galaxy we live in. A galaxy is composed of many stars. Our own Milky Way galaxy has over 200 billion stars in it. That is not an error. As you can see the distance is enormous. The Milky Way galaxy is shaped like a pin wheel. We are positioned on one of the outer arms. It is believed the diameter of the Milky Way is about 100,000 light years. But our galaxy doesn't occupy space alone, it is part of a group of galaxies that are known as the local group. The local group contains 3 large galaxies and over 30 smaller ones. Our Solar System is about 28,000 light years from the center of our galaxy. We now know we live in a spiral galaxy, but there are different types of galaxies. There are also Elliptical Galaxies, Lenticular Galaxies and Irregular Galaxies and variations of all. Lenticular Galaxies possess both a bulge and a disk but no spiral arms as do the Spiral Galaxies. Irregular Galaxies have no defined shape, are usually small and have no bulge. We think there are over 100 billion galaxies in the universe. As has happened many times in science, this number could turn out to only be a fraction of the true number of galaxies. One of the things I base this on is a very strange discovery. As we look further and further out with our telescopes we are supposed to be seeing into the past. The reason for this is it takes the light longer to reach us from a star or galaxy that is further away. Using this theory, we should see younger and younger galaxies and stars. Astronomers felt this was true and were looking at younger and younger objects. Then it happened, recently as they looked at what they thought was a galaxy that was formed near the big bang, they discovered it was an old galaxy. They haven't figured this out yet. So maybe the universe is a lot bigger than they thought or maybe there was more than one big bang and maybe there are a lot more galaxies than they think. The Big Bang is one of the most accepted theories on the creation of the universe. It states all the material in the universe formed info one massive unit, and that pressure caused an explosion sending the matter that formed all the galaxies, stars, planets and all bodies, shooting out into space. That would be the reason that everything is traveling outward.
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