Hi everyone! Here is my first Autumn post – it is not about travel, but something to contemplate with the change of season, as the stars become brighter with the coming of winter. We’ll have to find things to do when it’s cold!
Did you know that every night you can look into the past?
Just gaze at the night sky. What you see is what happened hundreds and thousands of years ago.
To understand this better let’s look at what a light year actually means.
It is not a measure of time as the name deceivingly suggests, but in fact a measure of distance. To be exact it is a distance that light travels in one year – 9,500,000,000,000 kilometers. Because some stars are so far away, writing out distance in miles/kilometers would simply look unintelligible to most. Instead, light years measurement is used. Why light? Because nothing in cosmos travels faster than light, and because it is the light we see reaching us from other stars.
Let’s say we are in the same room and I turn on the lights. You see the light immediately. But were you to be on a different planet, say 9,500,000,000,000 kilometers away from me, you would see the light I just turned on only a year from now. Of course, in reality, it would have to be a larger source of light to be visible at such distance – an exploding star perhaps. If the star one light year away from us exploded a year ago, we would see that explosion only now.
A star you see in a telescope that is 1 million light years away may look entirely different now, or might had collapsed and become a black hole, but you are seeing it now the way it looked a million years ago because it takes light from that star a million years to reach us.
Stars visible to a naked eye are tens, hundreds, and thousands of light years away. What we see in the night sky HAD ALREADY HAPPENED…