As you know, the planet Earth belongs to the Galaxy known as the Milky Way, but have you any idea how big, how extensive, this one Galaxy is? Or the distances between the stars? In reading Hoyle’s NATURE OF THE UNIVERSE, you can get some idea. Of course, astronomers use light-years in measuring the incredibly vast distances of the universe, but here again, its hard for a layman to even understand the distance involved in a single light-year.
It takes light just a little more than a single second to travel from the Earth to the Moon, so the Moon is a little more than one light-second away. It takes light about eight minutes to travel from us to the Sun, and we say that the distance of the sun is about eight light-minutes away. Now, if the Sun is eight light-minutes away (which is the time it takes to travel from the Sun to the Earth), try to imagine a single light-year!
And it takes light about three years to travel to us from even the nearest stars in our own Galaxy, the Milky Way. And when you look at the Milky Way with a small telescope you can see to a distance of more than a thousand light-years. But this isn’t much of a distance in this Galaxy of ours.
Our Galaxy is a thin disk about 60,000 light-years in diameter. It consists of stars and gas. Near its center the disk is very likely much thicker than it is at its edges. Our sun and our planets lie near the edge of the disk.
Now this immense disk of gas and stars is in motion, turning around in space like a great wheel. All are turning around the center of the Galaxy. The Sun and our planets move together as a group around such an orbit. We are traveling at a speed in the neighborhood of 1,000,000 miles an hour.
And to give you another idea of the size of our Galaxy, the Milky Way – even though we’re traveling with the Sun and the other planets at a speed of about a million miles an hour, one round trip around the Galaxy will take about two hundred million years!
This is a good time to reflect on how many ways you are now moving through space. In the United States you have a speed of about 700 miles an hour around the polar axis of the Earth. You are rushing with the Earth at about 70,000 miles an hour along its pathway around the Sun. There are also some slight wobbles due to the gravitational pull of the Moon and the other planets. On top of all this you have the huge speed of nearly 1,000,000 miles an hour due to your motion around the Galaxy.
Our Sun is a single star. There are more than ten billion stars in our Galaxy and nobody knows how many planets such as ours. And the Milky Way is just one of nobody knows how many galaxies.
The universe makes the wildest fiction of Jules Verne or Aldous Huxley seem simple and tame by comparison. It is unbelievable and true beyond our understanding. The human race, if all goes well, has about ten billion years left to figure it all out as far as this Earth is concerned. Understanding the universe and its size and content is surely one of the most fascinating studies open to man.
Coleridge wrote: “In wonder all philosophy began, in wonder it ends, and admiration fills up the interspace; but the first wonder is the offspring of ignorance, the last is the parent of adoration.”