The Universe

How Did the Universe Begin?  
The universe has been around for a very long time as one can image. It has been estimated that it began about 15 billion years ago. We can only look for clues as to how it began. We know that there is evidence that the galaxies are still expanding. Astronomers use the Red Shift of galaxies to tell them that they are moving further away. As objects move further away, the light spectrum given off by them tends to shift towards the red end of the spectrum. This makes them to appear redder than they actually are. The spectroscope is the instrument that astronomers use to detect this shift. They can use the red shift measure to determine how fast the galaxy is traveling.

There is still some warmth in the universe, which leads some astronomers to conclude that this heat is what is left over from the Big Bang. As a result, many astronomers agree with the theory that the universe started out with a huge explosion that shot all material outwards forming the galaxies and other bodies, known and unknown. We still do not know what caused the Big Bang to begin with.

There is still some speculation as to how the universe will end. Scientists have narrowed it down to two possibilities. Only time will tell which one of these possibilities is correct.

Possibility 1:   
The universe will continue to expand, eventually burning itself out. That is, it will begin to cool off as more material is scattered out further from each other. The effects of gravity will also decrease as matter moves further apart. This may eventually cause the expansion of the universe to increase further since gravity will become less and less as objects are moving further away.

Possibility 2:  
The universe will continue to expand. But, because the universe has an infinite amount of matter, the universe will expand only to a point. After that, the gravitational pull of this matter will cause all matter to more in again causing a Big Crunch. This will cause the universe to heat up as matter is moving towards each other. Finally, everything will collide, causing a dense center that will eventually become like a black hole. This dense object will have such a high level of energy, causing it to explode again forming the Big Bang and beginning the universe all over again.

Galaxies:
Galaxies are areas in space that contain huge concentrations of stars, planets and other celestial debris. In the universe as we know it, there are thousands of galaxies.

Galaxies are categorized according to their overall shape. These include:     

Galaxies often exist in groups or clusters. The Galaxy in which we live is part of a collection of 32 galaxies called the Local Group. The Andromeda Galaxy is the largest galaxy within the Local Group of galaxies. There are many groups of galaxies, which, in turn, form even larger groups called Super Clusters. The Local Supercluster is made up of several thousand galaxies scattered across 100 million light years of space.

Our solar system is actually a very small part of the Galaxy known as the Milky Way Galaxy. We are just part of a collection of a hundred billion stars that exist in space.

We live near the edge of this galaxy. As we approach the center of our galaxy, we find that they are many more stars in a smaller area thus increasing the overall temperature of the galaxy.

The Milky Way Galaxy is classified as a Barred Spiral Galaxy. It is so huge that it would take a beam of light about 130 000 years for it to travel from one side, through the middle, to the next. Keep in mind that light can travel 300 000 km a second.

Barred Spiral Galaxies are characterized with having bars of stars that begin to spiral near the edges of the galaxy.

Ordinary Spiral Galaxies, on the other hand, do not contain these bars of stars but rather, spiral arms of stars that end in a large center.

Elliptical Galaxies seem to have no real center and often appear from spherical to more elongated forms. They can range in size from very small to being among the largest galaxies in our universe. Dwarf Elliptical Galaxies are among the most common types of galaxies in the universe, however, they are also among the dimmest.

Irregular Galaxies are usually smaller and take on rather odd shapes. This is partly due to the gravitational forces of nearby, larger galaxies that pull them out of shape.

How Are Galaxies Created?
Supernovas play key roles in the development of galaxies. The debris that they scatter throughout space is the building material for other stars, planets, etc, adding to the overall makeup of a galaxy.

Galaxies begin with huge masses of dark gases that begin to shrink due to the effects of gravitational forces caused by dense materials. Some galaxies begin to spin forcing the outer areas to flatten out forming a spiral. Galaxies that do not spin will normally take the shape of a sphere or ellipse. The first stars are formed near the center. The gases or clouds of dust attract other clouds of dust forming more stars near the edges.

Our Milky Way: Data