A course in stars

Everything takes its time to happen. Light is not an exception here while it is very fast tho.
WiKi defines light as the radiant energy, usually referring to electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight.

Light travels at the fastest speed allowed by the law of physics (186, 287 miles/sec). But still it takes its time to get from one place to another. So, when we “see” anything, what actually happens is that our eyes detect the light which is either given off or reflected by it. It means that every-every-every object we see around us is in the past already. You are seeing them not as they are now but as they were a tiny, horribly small fraction of the second ago. Of course, light is so fast that over such a short distance it doesn’t really make a difference.

Things change when it comes to stars. The closest star to our planet is the Sun. Because the Sun is 149 600 000 km away from the Earth, it takes sunlight (sun rays) 8 min and 32 sec to get to our planet’s surface. What does it mean for us? Well, for example, if one day sun will die we will be able to see its light for whole 8 minutes and 32 seconds after it has gone.

Let’s go further out, to the next closest star to us, Proxima Centauri. That’s so far away that it takes light four years to get here (it’s four ‘light years’ away). It’s not likely to do so, but if it popped out of existence, exploded or turned into a giant frog right now, we wouldn’t know anything about it for another four years.

Now think about all the other stars up there- most of them are much, much further away: hundreds, thousands, millions and billions of light years away. If a star is a million light years away, and it died a million years ago, we’ll see it die now. If another star died four million years ago but is a hundred million light years away, we’ll still be able to see it for another 96 million years.

What about stars we see?

sun and earth positioning within 365

In fact, there are stars in every direction but we cannot see the ones on the same side as the Sun. Half a year later the stars that were hidden during local noon are visible at local midnight because the Earth has moved so as to show a different “side” to the Sun during that part of the day. This means that constellation (groups of stars) we see will change from winter to autumn.

And still, all these facts above, don’t make stargazing any less romantic.
So cuddle tighter and stay amazed, because all these stars… they shine for you

Безымянный

mood song: Coldplay “Yellow”.

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