Hundreds and Hundreds

ancient_stars

In a universe containing billions and billions of galaxies with billions and billions of stars (to use the mathematical notation of Carl Sagan,) people are getting it through their heads that when you talk about space, the numbers you use have to be big.

Looking up at the sky, I have been told that the light I’m seeing left its stars millions of years ago, and most of the stars are already dead.

It turns out this is totally wrong!

Starlight fades very quickly over distance, so 99% of stars visible to the naked eye are less than 1,000 light-years away. So the statement that the light has taken millions of years to reach us is bunk.

How likely is it that a star you’re looking at died within the last 1,000 years? Stars live for millions or billions of years. Out of the 100 – 400 billion stars in the entire galaxy, only one dies each year. So…not very likely. If I did my math right, there’s about a 1 in a trillion chance one of the visible stars has died.

So when you look at the stars, you can feel happy that they are not distant and dead, but close and very, very much alive.
Sources:

http://www.slate.com/blogs/bad_astronomy/2013/08/13/are_the_stars_you_see_in_the_sky_already_dead.html

curious.astro.cornell.edu/about-us/83-the-universe/stars-and-star-clusters/star-formation-and-molecular-clouds/400-how-many-stars-are-born-and-die-each-day-beginner

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