Heinrick Wilhelm Mathias Olber. Have you ever heard of that guy? Don’t worry if you haven’t. Most people do not have a clue who he was. In 1823 he asked what should be a simple question: Why is the sky dark at night? Maybe because the Sun is not shining? Actually, that is not the answer.
Over the years many people have thought about this problem, and it has become known as Olber’s Paradox. Even Edgar Allan Poe put in his two cents worth. It has only been in modern times that this simple question has been understood.
Here is how Olber looked at it: If the universe is infinitely large, and there are an infinite number of stars in it, and the universe is static, meaning it is not getting bigger, then the sky should not be dark at night. Everywhere you look, every line of sight should end at a star somewhere out there either near or far. So the entire sky should glow pretty brightly.
For stargazers this would be a real bummer. It would be like the worst light pollution imaginable, and you could not get away from it. It would be everywhere.
Even Olber himself did not get it right. He thought that the light from the stars was somehow absorbed by space itself while traveling through it. Only recently has mankind truly understood the reason the night sky is dark.
The universe is expanding. It is getting bigger and bigger. Everything far out there is rushing away from us as fast as it can. The famous American astronomer Edwin Hubble figured that one out. The light from those really distant stars has not had time to have gotten to us yet.
That is something to think about the next time you are standing out under a star-filled sky. There are trillions and trillions of stars up there that we cannot see because their light has not reached earth yet.
Closer by
There is plenty to look at up there that is not so far away. Take Jupiter for example. It is only 484 million miles distant. That is right next door. You might be able to get a glimpse of it low in the west in late May or early June. Otherwise, look for it in the morning sky low in the east before the Sun comes up later this summer.
Mars is in the evening sky but higher than Jupiter. Look for the red one. If you have a good pair of binoculars, it will bring out that red color very easily.
In the morning, brilliant Venus rules the sky. Look for her not long before sunrise in the east. Once a month a waning (that means it is getting smaller) crescent moon will come along and do a little dance with Venus for a few nights. Google Venus and lunar conjunction to find out when.
One more cool thing to look at. High in the east, a bright sort of orange-colored star can be seen. Its name is Arcturus and it is one of the brightest and oldest stars we can easily see. Want to know what our Sun will look like a few billion years from now? Check out Arcturus. Have fun stargazing one of these delightful spring evenings.
