Friday, August 24, 2007


The universe has a huge hole in it that dwarfs anything else of its kind. The discovery caught astronomers by surprise. The void is nearly a billion light-years across.

It isn't a black hole, which is a small sphere of densely packed matter. Rather, this one is mostly devoid of stars, gas and other normal matter, and it's also strangely empty of the mysterious "dark matter" that permeates the cosmos. Other space voids have been found before, but nothing on this scale.

"Not only has no one ever found a void this big, but we never even expected to find one this size." The universe is populated with visible stars, gas and dust, but most of the matter in the universe is invisible. Scientists know something is there, because they can measure the gravitational effects of the so-called dark matter. Voids exist, but they are typically relatively small.

How large is this new discovery? It's nearly a billion light-years in diameter.

Since it's a void, we can't take a photo of it. However, to see a depiction, click here. The image above is actually a
part of the three-dimensional distribution of clumps of dark matter in our universe, produced by an extensive survey using the Hubble telescope. Click here to read about that image.

How far is a li

A light-year is the distance that light traverses in one calendar year. The distance is easy to remember. It's 9.5 trillion kilometers so it can be rounded up to a tidy 10 trillion kilometers. In miles, a light-year is 5.9 trillion miles so it can be rounded up to an almost equally tidy 6 trillion miles.

We can try to grasp the magnitude of this number if we relate it to distances on a human scale. It's almost a hundred miles from Chicago to Milwaukee. It's two thousand miles from Chicago to Los Angeles. Our planet's diameter is about 8,000 miles. In our solar system, the earth is 93 million miles distant from the sun.

We've already gone to the sun and, still, the distance falls far short; far, far short of 6 trillion miles. It's simply just difficult to visualize and appreciate these distances.
On a cosmic scale, the kilometer or mile is just too small to be useful. (Let's stick with kilometers.) Astronomy, therefore, uses the light-year as its measuring stick. A light-year, to repeat, is 10 trillion kilometers.

There's a second way to comprehend a light-year. Don't express it as a number and, instead, express it as a unit of time.

Ten trillion kilometers is the distance that light will travel in a calendar year. A star one light-year away is 10 trillion kilometers distant. Since its light took a calendar year to reach us, then we're actually looking at the way it appeared one year ago. In other words, we're looking at a one-year old image of that star. (So much for "real time.") As it so happens, the nearest star after our Sun is 4.2 light-years away. When we look at it, we're looking at a four year old image of that star.

Earlier, you read that the earth is 93 million miles, or nearly 150 million kilometers, away from our Sun. If you do the math, it may surprise you to learn that it took eight minutes for the light of the sun to arrive to us. In other words, sunlight is eight minutes old.

We learned a second way to grasp these vast magnitudes. We can express distance in terms of time. The sun is eight minutes away. What about the moon? It's far enough that it takes 1.25 seconds for light to reach us. In other words, moonlight is 1.25 seconds old!

Keep this concept in mind.

The distance to the next nearest big galaxy, the sister of our own Milky Way,
the Andromeda Galaxy, is 21 quintillion kilometers.

That's 21,000,000,000,000,000,000 kilometers.
  1. A thousand has three zeros: 000.
  2. A million is a thousand thousand and has six zeros: 000,000.
  3. A billion is a thousand million and has nine zeros: 000,000,000.
  4. A trillion is a thousand billion and has 12 zeros: 000,000,000,000.
  5. A quadrillion is a thousand trillion and has 15 zeros: 000,000,000,000,000.
  6. A quintillion is a thousand quadrillion and has 18 zeros: 000,000,000,000,000,000.
The Andromeda Galaxy, as you see below, is an awesome sight. I had the privilege of seeing it.

This beautiful thing is 2.3 million light-years away. Put another way, we're looking at it as it looked 2.3 million years ago.

Back to the void.

How large again is this newly-discovered void? It's estimated to be a billion light-years across. That's nearly 500 times the distance from our galaxy to Andromeda.

That void is so large that the light of a star at one of its ends would take a billion years to reach the opposite end!

God works on a vast scale, doesn't He?

The Source Document

here for one of the news reports that announced the discovery of this huge void. This void was just discovered.

Sphere: Related Content

No comments: