Objects in Space and Their Relative Size When we talk about space it is hard for us to understand how many things are out there and the size of objects. We all know there are a lot of objects in space and things range in size from unbelievably small to incredibly large. There are also so many objects in space they outnumber the grains of sand on all the beaches of earth. Recently, a question was put forth which asked how many galaxies are there within our range of vision using the instruments we have available today? The scientists responded by saying there could be so many stars they outnumber the grains of sand on all the beaches and trillions of galaxies in the observable universe. I think they were light on this answer because there may be some galaxies in front of others hiding them. I don’t think we can count how many galaxies there are within our visual range yet. So how does a scientist decide how many galaxies we might be able to see? It seems like an impossible task, doesn’t it? They take a small section of space and count how many galaxies they are able to see in it, then they multiply that number by the number of sections which are left. While this may be all we can do to try and get a close number, it may turn out it is not very accurate since the number of galaxies in each section might vary greatly. When we look at this number, we have to realize what a galaxy is. We live in one and it is called the Milky Way. The Milky Way was considered to be about a hundred thousand light-years across until recently, now it is being said it could be double that size. When we try and figure out how many stars are in the Milky Way there seems to be a lot of different estimates. One estimate from the European Space Agency claims there are 100 billion stars in the Milky Way, but not everybody agrees about this. Some scientists say there are 100 to 400 billion stars in our Milky Way and our galaxy certainly is not the biggest. We are just getting started counting planets in the Milky Way, but the current estimate states there are about 400 billion planets. If we accept the estimate of the size of the galaxy, we live in as being 100,000 light years across, then we have to realize there are plenty of other galaxies far bigger. Take the galaxy Hercules A for example. It is 1½ million light years across. Galaxies range in different sizes across our universe and the smallest one we found so far is a dwarf galaxy named M60-UCD1. It is estimated to be 300 light years across. It is said our galaxy is pretty much average in size if we accept the 100,000 light year size. I would also like to mention it is 3000 light years thick. One thing which has surprised some scientists is the fact a small galaxy can have a huge black hole at its center. Right now, it is thought black holes might exist in every galaxy. The biggest black hole found today exist in the Abell 85 galaxy. It is so big it’s 40 billion times the mass of our sun. If this black hole existed in the Milky Way galaxy it would take up two thirds the mass of all our stars. The black hole is actually bigger than the mass of many galaxies. Scientists tell us black holes exist in almost every galaxy. It has been thought they are objects which have collapsed and have such incredible gravitational force nothing could escape them. Some people even believe there are black holes or a black hole so large beyond our vision, it is responsible for the universe being drawn to it. This is just a theory of course, but we do know the universe is expanding. In the scheme of things, we have just begun discovering Exoplanets. These are planets outside of our solar system. They vary in size and small ones are called dwarf planets. Our own planet Pluto was reclassified from its planet classification to dwarf planet because of its size and a discussion about this still rages on today among scientists of whom some agree with the reclassification and some do not. As of this date, 19 April, 2020, the largest exoplanet found isTrES-4. It is about 1.7 times the size of Jupiter and is considered to be a puffy planet. Scientists use the word puffy for planets that have extremely low densities. To understand this, think of a piece of balsa wood which would be about the same density as that planet. The smallest exoplanet we have found so far is Kepler-37b. It is slightly larger than our moon. I think there is something we have to understand about this first and that is discovering Exoplanets using our current technology may preclude us from finding some which exist. This means there could be bigger ones which we missed, or smaller ones. Many science fiction movies depict a media storm in space, did you ever wonder if this was truly a danger for space travel? This danger could probably be avoided in the future by steering around it if the ship had enough notice, it seems that the biggest danger for an unshielded ship are micro-meteors. These are tiny sand sized grains. Most people would never think of these as being dangerous because they are so small, but look at it this way, if one of these is traveling at a high speed which is thought to be about 7 to 45 miles per second and it hits a ship traveling forward at perhaps 25,000 miles per hour or greater, the impact would contain a tremendous amount of energy. One tiny grain of sand could penetrate a ship and come out the other way as it went through people and devices. It is hard to visualize, maybe I should say impossible to visualize the sizes of things when we talk about the universe. How does one visualize an object which is many billions of times the mass of our sun? I know I find it is very hard to wrap my mind around this. When you consider this is far from the biggest thing in our universe it bends our minds even further. One has to wonder if we will ever be able to travel through space to anywhere outside of our solar system, when you consider the huge distances and the dangers awaiting those brave souls. We are going to need speed, protection in the form of shields and the ability to land in places which are not conducive to human life.
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