astronomy_jag

I am copying all of my astronomy paragraphs in here. I am giving them a proper title. I am adding pictures to go with each paragraph.

Though our universe was created in only a matter of minutes, it is made of millions of different components and is still growing today. About 15 billion years ago, our universe exploded out of nothing, within an unimaginably small fraction of a second. The event is now called the Big Bang. The earliest forms of matter in the universe were quarks, antiquarks, and energy. Before the universe is a tenth of a millisecond old, the temperature began to drop, and protons and neutrons started to form. Three minutes after the Big Bang, one fourth of the protons and neutrons combined to make helium nuclei, and the temperature continued to drop. For the next 300,000 years, not much changed. When the temperature got down to 3,000 degrees Kelvin, electrons began to orbit the nuclei, creating the first atoms. The formation of galaxies began 2 billion years after the Big Bang. Gravity caused clumps to form, creating masses.
 * From Big Bang to Galaxies**



Galaxies began to form when gravity caused clumps of matter to grow and become denser. The formation of galaxies began 2 billion years after the Big Bang. Because gravity was distributed unevenly throughout the universe, clumps of matter didn’t form in all areas. The universe took on a sponge like structure. Galaxies began to form in the strands of matter in the universe. The Milky Way galaxy began to form when the universe was about 3 billion years old. It started out as a large ball of gas, which eventually settled into a disk surrounding a central bulge. The spiral arms then developed from the rotating disk.
 * Formation of Galaxies**



The Milky Way galaxy is a spiral galaxy, meaning that it has spiral structures extending from the center of the galaxy. When looking edge on at the Milky Way galaxy, it is about 100,000 light years across. If you are far enough away, you will see one long disk, cutting across a central bulge in the center. The bulge is the galaxy’s galactic center. Collections of stars are spread out around the Milky Way galaxy for about 130,000 light years out. Our sun is about halfway out from the bulge on one side. On the other side of the galactic center, a dwarf galaxy is merging with the Milky Way galaxy. When looking down on our galaxy, there are four spiral arms winding out from the central bulge. They consist of young stars and hydrogen gas, and move in a counterclockwise motion. The central bulge is made of tightly packed yellow and orange stars. In the very center of the bulge, there is believed to be a massive black hole.
 * Structure of the Galaxy**



Every star and gas cloud in the Milky Way galaxy has its own orbit. Our sun takes 250 million years to travel around the central bulge once, even though it consistently travels 250 kilometers a second. Some matter orbiting the central bulge isn’t always in our solar system. Some matter temporarily piles up on the spiral arms that wind out from the central bulge for a short time. It doesn’t stay there permanently, but they turn with the galaxy for a certain amount of time. By studying the rotation of the galaxy, it has been discovered that the Milky Way galaxy is surrounded by a large, invisible corona. The corona contains ten times more material than we can see, in the form of stars, gas, and dust. Just by studying the rotation of the galaxy, we have also been able to predict that our galaxy may be five times larger than we imagine.
 * Rotation of the Galaxy**



The planets in our solar system were formed mainly by clumps of mass colliding and sticking together. About 4.5 billion years ago, a flat disk of gas and dust circled around the Sun. In the disk, solid materials began to collect into larger particles that later formed clumps. The clumps of matter often collided with each other, creating larger clumps. In the outer solar system, many collisions occurred, and four large clumps formed. These are now the planets Jupiter, Saturn, Uranus, and Neptune. In the inner solar system, there were too many collisions for giant gas planets to form. Eventually, four fairly large masses formed, and are now known as Mercury, Venus, Earth, and Mars.
 * Formation of the Planets**



Most of the Milky Way Galaxy’s moons, rings, and comets were also created by collisions. The Earth’s moon was believed to have been created by a rather large collision between the Earth and another planet of about the size. During the collision, pieces of rock were separated from the Earth. Over time, they reformed to create the moon, which was eventually pulled in by Earth’s gravity. Another way that moons were formed is very similar to that of planets. Most planets in the outer solar system formed disks of gas and dust of their own, in which clumps formed. The clumps eventually became large enough to orbit a planet, and then were stuck as moons. Some of the inner planets simply captured stray pieces of rock for their moons.
 * Formation of the Moons, Rings, and Comets**



Return to Julia G. webpage