By David Ward
Have you ever been out under a dark night sky filled to the brim with stars? Maybe you were camping out somewhere in the wilderness far away from city lights. Maybe you wondered how many stars you could see. I often ask this question at a star-gazing program. The answer is usually millions and millions, or sometimes someone insists they can see even billions of stars.
Estimates vary, but if you are in a very dark place with a low horizon, no moon and your vision is excellent, then you might be able to see 4,000 or 5,000 individual stars.
I know that does not sound like a lot, but there are many, many more stars out there. For every star we see there are at least 20 more we cannot see. Not because they are farther away, but because they are too dim and our eyes are just not sensitive enough to pick them out.
Scientists studying the migration of humpback whales are amazed at how they can travel such vast distances across the ocean in almost perfectly straight lines. The thinking goes that they may actually navigate by the stars. Their pupils are so much larger than ours that they probably see many more stars than we do.
So how many stars are really out there? If you have a pair of binoculars, just gaze up at any part of the night sky and more stars will pop into view, enabling you to see about 100,000 of them. A small telescope will reveal 5,000,000, but it would take forever to carefully examine every patch of sky to see them all.
Even millions is just a small portion of the huge number of stars that inhabit our galaxy, the Milky Way. Astronomers estimate our galaxy has a population of 200 billion to 400 billion stars. Let’s average that out to 300 billion. That is a huge number — 300 billion seconds ago happened in the year 7,495 B.C.; $300 billion would be a stack of one thousand dollar bills almost 20 miles high. That is a lot of stars!
But wait a minute. There are other galaxies out there beside the Milky Way. Our next-door neighbor, the Andromeda Galaxy, has many more stars, maybe as many as a trillion, and there are plenty of other galaxies in the universe.
One of the most amazing astronomical pictures was taken by the Hubble telescope. Astronomers picked a tiny random spot up in the Big Dipper and took a photo to see what was up there. Amazingly, they counted over 3,000 galaxies, each containing billions of stars, in an area of sky not much bigger than a grain of sand. That means there are hundreds of billions and perhaps trillions of galaxies out there.
So how many stars are there? The short answer is lots and lots. Picture yourself on your favorite beach. Can you imagine counting all the individual grains of sand there? That would be quite a task as each handful contains about 10,000. How many sand grains would be in all the beaches in the world? Now add in all the deserts too. The number of sand grains on the planet Earth is so large that we cannot even begin to comprehend it. There are more stars in the visible universe, the universe we can see with our telescopes, than all the grains of sand on earth, a lot more.
The next question is, what is beyond the visible universe? Is there more? Most astronomers would answer yes. There is more, a lot more, but I am not going into that now. Ask me at one of my star-gazing programs this summer.
What you can see now is the planet Venus shining brightly in the west just as it is getting dark. Jupiter, another bright planet, is coming up in the east and will dominate the night sky late spring and early summer. The bright stars of winter are disappearing into the sunset, but more are taking their places in the east.
If you are lucky enough to find yourself somewhere remote and dark at night and you can see 4.000 or 5,000 stars up there in the heavens, remember that is just half a handful of sand from all the deserts and beaches in the world.