Is anyone there knows about this book? if your willing to know about this book let me share it to all of you steemians.
The Milky Way galaxy.
Stand outside on a clear night and look up. How far can you see? How much can you see? Have you ever seen the Milky Way? On very special dark nights, if you live far enough from the city lights, you can see a broad swatch of light across the heavens. It's a view in toward the center of our Milky Way galaxy, where the stars seem so close together that they blend into a milky white glow.
Since our solar system rotates around a pale star in one of our galaxy's spiral arms, we are a long way from the center of the action. We're in the suburbs of our own galaxy, a tiny spot in a sea of roughly two hundred billion stars.
Two hundred billion stars- but even on the darkest night with the clearest skies, our human eye can only actually see about three thousand of them at any given moment. There are less that nine thousand stars visible from the earth with the naked eye, and those " nearby" in our own Milky Way.
We used to think that the earth was the center of the universe, that the sun and all the stars rotated around it. But as soon as the telescope was invented, we discovered that we were wrong. Each time we've invented a stronger telescope, we've learned that the universe is bigger than we thought. We've discovered a universe so big that not just our little planet, or our weak sun, but our entire Milky Way galaxy is just a spot, a blip, barely worth noticing.
How big is the universe? Bigger than we think. Bigger than we can even imagine! Let's see if we can wrap our minds around some of the numbers
How far have you traveled in the last year? Twenty thousand miles? Fifty thousand? Many people who fly for business regularly travel one hundred thousand or more miles every year. We can easily see the moon when we look up into the sky- it's only about two hundred fifty thousand miles away. We can also see the sun- although we shouldn't look directly at it. It looks as if it is about the same size as the moon, but really it's just a lot farther away-ninety three million miles. It's so far away that it takes sunlight over eight minutes to reach the earth!
How big is the sun? About a million earths would fit inside it. If the earth were the size of a coin, the sun would be as big as a nine-foot beach ball. That is almost too big to imagine! The sun has to be the biggest thing in the universe, doesn't it?
The Orion Nebula
Well, no. Have you ever looked up to see the constellation Orion the Hunter in the sky? Betelgeuse, the bright star on Orion's top-left shoulder, is so big that if it was the star in our solar system instead of the sun, it wouldn't fit into the big circle the earth makes when it circles the sun from ninety-three million miles aways. It wouldn't even fit inside the orbit of Jupiter and that's 484 million miles from the sun!
But the largest known star is called Canis Majoris. It's so big that if earth was size of a coin and if our sun was ninety-foot beach ball, how far away would the sun be? About the length of a ball field. In fact, if our entire solar system- the sub and all tye planets- was the size of a coin, the sub would be visible only under a microscope, and the nearest star would be three hundred feet away. If you could travel at the speed of light that's 186,000 miles per second- it would still take one hundred thousand years just to travel across our galaxy!
If our whole galaxy was the size of a coin-remember, that's two hundred billion stars-our solar system would be too small to be seen under a regular microscope. The other galaxies out there would still be from one foot to one thousand feet away.
So many galaxies! So many stars!
And how many other galaxies are there? In an attempt to sew deeper in space than ever before, astronomers focused the Hubble telescope on a seemingly empty patch of the night sky.
The Hubble telescope
Empty-no visible stars,galaxies, or anything. They focused on nothing for eleven days, the carefully examined the photograph. In this tiny little spot-about- 3 percent of the size of a full moon- they found more than ten thousand galaxies-not stars, but entire galaxies of stars-each with billion of stars.
The Whirlpool galaxy
When they focused the Hubble telescope there for twenty-three days, they found that they could see even more galaxies-almost twice as many. Based on these deep field studies, astronomers estimate that there at least 175 billion galaxies within their current view from earth. How many stars would that be? if we consider our galaxy's two hundred billion to be average, there are something like 350,000,000,000,000,000,000,000 stars by my calculation. Until we develop the technology to see deeper or father into space,anyway.
Think about it this way: the next time you're on the beach, pick up a handful of sand. If the estimate are right, there are more stars in the universe than there are grains of sand on all the beaches in the world. What we see when we look up- it's only a handful of sand.
We've certainly learned that earth is not the center of the universe. But for many years we've wondered whether or not earth was unique-whether it was the only planet in the whole universe. Recently, we've learned that most star systems have planets. In our galaxy alone, the estimate is that there are more than billion planets.
TO BE CONTINUED....
This is only the chapter 1 of the book, the chapter 2 will be posted later. Hope all of you will enjoy reading this, looking forward that everyone can get more knowledge about our universe.
