## What Are Galaxies?

Galaxies are a cluster of stars that usually orbit a super black hole. Galaxies vary in sizes, some are very tiny, as small as 15 light years across, or a spiral galaxy like the milky way and Andromeda galaxy which are thousands to millions light years across. Galaxies follow an organization that is a disc, unless it is an irregular type of galaxy. There are elliptical galaxies, which is a cluster of stars that are organized by gravity to make a galaxy that looks like a disc without any unique structures. Spiral galaxies are galaxies that have multiple tails at their edges that start from the center of the galaxy. The milky way galaxy that we live in is a spiral galaxy. There are some galaxies are there that do not orbit a black hole and are out floating and they're said to be a part of a galaxy that collided with another galaxy and had been thrown out of their orbit. These are called irregular galaxies because of their their is not symmetrical.

## Saturday, March 12, 2016

### Lagrange Points

Lagrange points are points between two or more objects in space in which gravity is equal. For example, L1 (Lagrange 1) is between an object, like Earth, orbiting a star, like the Sun. There is a point in which an object will orbit between the Earth and Sun and stay in an orbit that is equal to the amount of time it takes for Earth to complete it's orbit. Let us say, there is a satellite we need to orbit in this area for studying asteroids without going into the asteroid belt for obvious reasons. We can achieve this by launching the satellite a certain distance between the Sun and the Earth and it will have the same orbital period as the Earth. This seems impossible, but that is only because there wasn't any factor of the pull of the Earth v. Sun. The closer you are to an object, the strong the pull is. The Sun is at a much greater distance than the Earth, so to have a stable orbit that follows Earth's, the satellite would need to be at the point in which the gravitational influence is almost equal. This is the basic concept of the Lagrangian points and there are up to 5 different points in which gravity will equal itself out, though, these points are unstable and require correction by using fuel and burning it to achieve this.

## States of the Universe

My definition of States of the Universe doesn't mean the physical states of matter or physics. Rather, from birth to death and it's properties. The Universe has a theory (tested hypothesis that scientists agree on) of the birth of the Universe. This theory is called the Big Bang Theory, though, the name is miss leading, it sounds better than the "Rapid expansion of space" theory. This was said to be a violent event that lasted less than a second to which matter can cool down and form bodies of mass and objects. Refer to the picture above. We do not know, however, the before of the Big Bang event. There isn't evidence to help support any ideas that hypothesis the idea of a beginning before the beginning. Though, there are good ideas and theories that explain how it came about. The Multiverse theory and string theory both explain multiple universes that exist and have evidence of which why that could be. This could explain how the birth of the Universe happened, but not why.

The Universe right now, is still in expansion, known as the red shift effect, in which light will shift toward the red spectrum and beyond due to the rapid expansion of the Universe. This will make our vision of the universe's light not seen in the future. To the point in which the observable universe will have to be done with microwave/radiowave telescopes.

## Oort Cloud

The Oort Cloud is an idea that there are materials orbiting the Sun which gives the formation of comets and possible the planet nine hypothesis. There isn't a lot of proof that it exists, but it makes sense if it would exist, so right now, it is still a hypothesis that has many theoretical ideas to it but it isn't narrowed down to what we would consider a theory. The Oort cloud may be responsible for newer comets being discovered and older ones being able to come back for quite some time. Comets are an ice rock in space, so it would make sense that it would be formed outside the asteroid belt and outside the planets since it was undetected for quite a while until arrival. This ice is not ice of pure water, though, it does contain water along with carbon dioxide, methane, carbon monoxide and ammonia. These elements freeze at a very low temperature of 20*K or lower (*K = Kelvin). It makes sense that since newer comets arrive, that there is something in which they are created and the Scientist have a good idea this is where they came from.