Hello dear readers!
Most have heard the term "light years away", perhaps at school, on television or have read in some news with scientific themes. We imagine, perhaps because of logic that are great distances, but you really know what is meant by this unit? That's why today we want to share the following article.
What is a light year?
By: Francisco J. Sánchez Marín *
Astronomers are used to talking about light years. Often say, for example, that the star Sirius in Canis Major (the brightest in the sky after the Sun) is 8.7 light years from our planet. But what does that mean?
happens that the stars are so far from our planet Earth is not practical to make use of units such as kilometers to measure how far they are from us.
Returning to our example, if we use the miles would to say that Sirius is 82308960000000 kilometers of land. It's not as easy to read that number right? This is what is called astronomical distances.
To make things simpler, astronomers use what is called a light year. A light year is the distance light travels in one year. That is, if we consider that light travels at a speed of 300.000 miles per second, we can give an idea how far a light year equals. Accounts do: if an hour includes 3600 seconds, a day equals 86,400 seconds and a year to 31,536,000 seconds. If we multiply this last number by the speed of light get 9460800000000, which is the kilometers distance light travels in one year, ie given a light year in kilometers.
said, it is interesting to think that when we perceive the image of Sirius, the image was formed with the light from Sirius 8.7 years ago. That is, the image we perceive is the Sirius when it was 8.7 years ago where we see now. Then, if the vast majority of stars are many light years from our planet, when we look at the sky on a starry night What we're seeing?
* http://www.cio.mx/web_ant/curricula/s_fsanch.html
photo: http://itaca.zonalibre.org/archives/universo.jpg
