Units for Distance and Size in the Universe

Astronomers use many of the same measurement units as other scientists. They often use the length of the meter, the kilogram to the mass, and the second in time. But the distance and size of the universe are so large that astronomers invented more units to represent the distance.

Distances within the solar system are usually measured in astronomical units (abbreviated AU). Astronomical unit is the average distance between the earth and the sun.

Jupiter is about 2 AU from the sun, Pluto is about 39.5 AU from the sun. The distance from the sun to the center of the Milky Way is about 7 × 109 AU.

To measure the distance between stars, astronomers usually use light years (abbreviated as ly). The light year is the distance the light travels in a vacuum within a year.

Proxima Centauri is the closest star to the Earth (excluding the sun) two light years away. This means that light from Proxima Centauri will take two years to reach Earth.

Many astronomers like to use parsecs (pc for short) to measure distances from stars. This is because its definition is closely related to the method of measuring distances between stars. Parsec is the angle corresponding to 1 AU and one second.

Astronomers examine celestial objects ranging from very small ones (including atoms and nuclei) to very large ones (including galaxies, galaxies, the size of the universe). In order to explain such a huge range, astronomers need a way to avoid confusing terms such as "billions of dollars" or "parts per million". Astronomers use a system called a squared representation that combines all zeros that are normally found in a very large or small number like 1,000,000,000,000 or 0.000000001. All zeros are placed in indices written as superscripts and indicate the number of zeros required to write long form numbers. For example,

In a power expression of 10, this number is written as a number between 1 and 10 multiplied by a power of ten. Thus, for example, the distance to the moon of 384,000 km can be rewritten to 84 x 105 km. 84 is between 1 and 10. The same number can be rewritten exactly to 38.4 × 104 or 0.384 × 106, but the first number is preferably the one between 1 and 10.

You can also write a very small number using a power expression of ten. For numbers less than 1, the exponent is negative, indicating division by 10. For example,

Again, this number is written as a number from 1 to 10 multiplied by a power of ten. Therefore, for example, a number such as 0.00000375 is expressed as 75 × 10-6.

The reason why the universe seems to be restricted to us - we can not see the reason beyond a certain distance - not because the size of the universe is actually restricted. If you do not understand the Big Bang anything else, it will look something like this. The universe is not constant both spatially and temporally, but it evolves from a more uniform, hot and dense state to a more concentrated and cold state of the day. More dispersed state

So we know that the size of the observable space is 93 billion light-years, 46 billion wireless, so we need to know which part of the horizon of the universe has a causal relationship with us there is. The known universe. The current instantaneous distance is the distance that must run only when the expansion of the universe is frozen, and is called the appropriate distance, but in practice the shortest distance is defined by the geodesic line. Even between optical paths, it is necessary to filter the time interval. The closer you are to the destination, we will go farther, do you have to travel? Even if you are on a spaceship, we have to move infinitely quickly.

When I was young, when I first saw the calculation of the distance between the universe and the light year (the distance the light travels in a year), I wonder how big the universe is and how long it is for humans to stay I learned why it is impossible to search out of time. In the universe, the human body does not yet know what will happen. Why do not you call a volunteer in your 20s who can participate in the experimental space program in order to travel without knowing the tiredness in the universe? This includes spaceships based on space cities that house the Earth 's atmosphere. 99 young people of different countries and races live and give birth on space travel, bring up children to future astronauts, and they inherit the infinite mission of finding lives in outer space.