Astronomy_sra7

How the Universe Came to Be The entire universe was created about 15 billion years ago, during an event called the Big Bang. The universe exploded out of nothing, and started out as radiant energy and exotic particles, such as quarks and antiquarks. The universe continued to expand and cool down at a steady rate. Very soon into the creation of the universe, protons and electrons are being created. As the temperature falls, annihilation of particles takes over, and creates energy. Soon, helium nuclei are created. For the next 300,000 years, very little happened. Once the universe cooled down to 3,000 degrees Kelvin, it was cool enough for electrons to orbit protons. Particles slowly collected, and eventually came to where we are now.

 How Galaxies Came to Be﻿  Galaxies were created 2 billion years after the Big Bang. Wherever there was a slight difference in the distribution of matter through the galaxy, the action of gravity took place, and caused matter to grow. The universe became sponge-like after this. Galaxies were created in small shells in huge webs surrounding empty voids. Galaxies start as huge spheres of gas. Some of the gas settles in a huge spiral disc surrounding a central bulge, and created spiral arms. Small chunks of matter collected, and created the solar system. Our Galaxy- The Milky Way Our galaxy is centered around a central bulge. This central bulge is most likely a black hole. This bulge is surrounded by a thin disk of stars. A very thin layer of gas and dust cuts through the middle of this disk. Our sun lies in the disk of stars. It is about halfway between the end of our galaxy and the central bulge. On the opposite side of the galaxy, a dwarf galaxy is merging with ours. Surrounding our galaxy is a random scattering of stars and globular star clusters. Four spiral arms come out from the central bulge. These arms show where matter has settled temporarily.  How Our Galaxy Rotates The Milky Way galaxy is constantly turning. But it's turning is different from that of a rigid disk. Every single star and gas cloud are in their own orbit while the entire galaxy turns also. Our sun takes 250 million years to go around the galaxy once. The entire galaxy is rotating, with the inner parts of it rotating also. ﻿How the Planets Came to Be ﻿ The formation of our planets was a long process, taking many years. In the beginning, there were clumps called planetesimals. At first, planetesimals were close, and would crash and annihilate each other. Afterwards, some planetesimals collided gently enough to clump together, and become a larger mass. These grew larger and larger, creating the planets. In the further reaches of the solar system, gas giants were made. These were made mostly of gas. Nearer to the sun, rockier planets were created, since gas would be blown away.

 ﻿How the Moons, Comets, and Rings Came to Be <span style="color: #0000ff; display: block; font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 24px; text-align: left;">Moons, rings and comets were all created by planetesimals, gas, and dust. Moons were created when the gravitational pull of a planet pulled a planetesimal into orbit. The exception is our Earth. Since the moon is 1/6 the size of the Earth, Earth could not have pulled it in using gravity. Scientists believe that a planet about the size of Mars may have collided with Earth, creating the moon. Rings were created by ll stray planetesimals and comets being torn apart by the gravity of a planet. Rings are usually only seen around the planets with larger masses. Comets are usually icy planetesimals from the further reaches of the solar system coming close the sun. Return to Main Page