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Looking Back in Time

Observing >

One of the more remarkable things about studying the universe is that astronomers can actually see the past as it happens. Paleontologists and historians can only play with relics from the past and try and figure out the course of events.

Astronomers can actually see the past happening now. How can this be?! Well, first I have a confession. It's not just astronomers that can witness a dynamic past --- we all can and do. Let me explain.

Light travels. It takes time for it to go from one place to another. Granted, it travels really, really fast, but it still takes some amount of time.

And because it takes time, we end up "seeing" events after they have already happened. More bizarre, the farther away something is, the farther light has to travel, and the farther back in time we are looking. Here are some examples:

The light reflecting from my wife across the room took about a billionth of a second to hit my eye. I, therefore, see her now as she looked a billionth of a second ago. The Moon, on the other hand, is far away enough that it took light over a full second to get here. We see the Moon as it looked about a second ago.

Go out and look at Mars tonight and see how it looked a long time back --- over four minutes ago to be more precise! Our sun is considerably farther. Its blinding light takes over eight minutes to finally reach Earth.

Now let's go to the other stars! Look tonight for the bright reddish star a little to the right of Mars. That star, Antares, is over 600 light years away, meaning it takes light 600 years to get here! The light we see now left Antares in about the year 1400, about the last time the Angels won the Pennant.

But seeing 600 years into the past is nothing.

In 1987, people in the southern hemisphere witnessed a supernova explosion --- the obliteration of a massive star --- in a nearby galaxy. But the explosion actually happened about 170,000 years ago! It just took that long for the light from the blast to reach our eyes.

The nearest galaxy visible to everyone in North America is the great spiral of Andromeda. It is over 2 million light years away!

You see the pattern here. The farther something is, the longer its light takes to travel here, and the farther back in the past we are looking. We see the past happening now, before our very eyes.

And the universe goes out much, much farther and deeper into the past. When we look with something like the Hubble or Keck telescopes we can see billions of years into the past, when the universe was just a nipper.

All this is not just another awe-inspiring phenomenon of our universe. It is also a tool for astronomers. Looking all the way back and then working forward, cosmologists can see how this universe is changing and forming over time.

And this ability to look back in time has greatly increased our appreciation of planet Earth in this Whole Scheme of Things. One thing we have learned by looking back is that right here and now is the perfect time and the perfect place in the perfect galaxy for a small, rocky planet orbiting a lonely second generation star to be the perfect home for you and me.

Until next time, clear skies!

Mark Ritter, who dresses now as in the past, can be reached here.

Posted by Administrator at 2001.07.21 08:19 AM | Comments (0)

Globular Clusters

The Galaxy >

Summer is a great time of the year to be taking a look at globular clusters. If you can get yourself a pair of binoculars, or better, a small telescope, you should go out some time soon on a moonless night and appreciate the subtle beauty of one of these creatures in the dark.

Globular clusters, aka "globs" in the astro-biz, are ... well ... clusters of stars that are shaped like ... globules! Scientific terms may not be too poetic, but they're pretty descriptive.

Globs aren't just cute wee clusters of stars, however, like grapes on a vine. Oh no! They are menageries of stars that number in the hundreds of thousands! If we lived in a glob we'd have a night sky with tens of thousands of brilliant, bright stars all round. From here, though, they appear only as symmetrical fuzzballs through an eyepiece.

But their descriptive moniker doesn't explain why they are the way they are or even how they got here in the first place. Inquiring minds for the last hundreds of years wanted to know.

So inquiring minds found out.

As early as the beginning of the 20th century, it was believed that our solar system was the center of the Milky Way Galaxy.

But then Harlow Shapley came along. (Yes, Harlow Shapley!)

While studying the distribution of globs around the skies Shapley realized that they aren't hovering around our system; they seem to be hanging out in an area way over there in the constellation Sagittarius. He assumed these little clusters were moving about that area because that was the center of the Galaxy. He was right.

With that observation, and with more he and his colleagues would make in the next decades, they painted a New Picture of this hugely massive universe we live in and changed the face of astronomy for good.

It turned out that globs are not only the most compact groups of stars in our galaxy, they are also its oldest stars, the oldest amongst them being over 10 billion years old! In comparison, our sun is a second or third generation star in the disk of our galaxy and is only a middle-aged 5 billion years old.

The latest and best theories say that globular clusters were the first things formed in our galaxy, before it flattened and went spiral leaving the globs to hover about it like bees around a huge flower. Globs, it turns out, are the senior citizen communities of spiral galaxies and as such should be treated with the respect they deserve.

You can spot some globs tonight! Go out at about 10 PM, with binoculars or telescope and look directly above you. There is center of the constellation Hercules which is shaped like a keystone. Look for the two keystone stars on the western side. Between them you'll see a fuzzball. That's M13, one of the most stunning globs of all.

Now look to the south. See that reddish star to the "right" of Mars? That's Antares in the constellation Scorpius. Just to its right is another fuzzball, the glob dubbed M4.

Now look to the "left" about 30 degrees, to the teapot-shaped constellation next door to Scorpius called Sagittarius. Just to the left of the top star of The Teapot is another glob, M22. The heavens have many, many more you can discover for yourself just by carefully scanning the skies.

Have fun! There are maps and images awaiting you at firstlightastro.com. Until next time, clear skies and happy hunting!

Posted by Administrator at 2001.07. 7 08:22 AM | Comments (0)



Looking for something?	« June 2001 \| Main \| August 2001 » Looking Back in Time Observing > One of the more remarkable things about studying the universe is that astronomers can actually see the past as it happens. Paleontologists and historians can only play with relics from the past and try and figure out the course of events. Astronomers can actually see the past happening now. How can this be?! Well, first I have a confession. It's not just astronomers that can witness a dynamic past --- we all can and do. Let me explain. Light travels. It takes time for it to go from one place to another. Granted, it travels really, really fast, but it still takes some amount of time. And because it takes time, we end up "seeing" events after they have already happened. More bizarre, the farther away something is, the farther light has to travel, and the farther back in time we are looking. Here are some examples: The light reflecting from my wife across the room took about a billionth of a second to hit my eye. I, therefore, see her now as she looked a billionth of a second ago. The Moon, on the other hand, is far away enough that it took light over a full second to get here. We see the Moon as it looked about a second ago. Go out and look at Mars tonight and see how it looked a long time back --- over four minutes ago to be more precise! Our sun is considerably farther. Its blinding light takes over eight minutes to finally reach Earth. Now let's go to the other stars! Look tonight for the bright reddish star a little to the right of Mars. That star, Antares, is over 600 light years away, meaning it takes light 600 years to get here! The light we see now left Antares in about the year 1400, about the last time the Angels won the Pennant. But seeing 600 years into the past is nothing. In 1987, people in the southern hemisphere witnessed a supernova explosion --- the obliteration of a massive star --- in a nearby galaxy. But the explosion actually happened about 170,000 years ago! It just took that long for the light from the blast to reach our eyes. The nearest galaxy visible to everyone in North America is the great spiral of Andromeda. It is over 2 million light years away! You see the pattern here. The farther something is, the longer its light takes to travel here, and the farther back in the past we are looking. We see the past happening now, before our very eyes. And the universe goes out much, much farther and deeper into the past. When we look with something like the Hubble or Keck telescopes we can see billions of years into the past, when the universe was just a nipper. All this is not just another awe-inspiring phenomenon of our universe. It is also a tool for astronomers. Looking all the way back and then working forward, cosmologists can see how this universe is changing and forming over time. And this ability to look back in time has greatly increased our appreciation of planet Earth in this Whole Scheme of Things. One thing we have learned by looking back is that right here and now is the perfect time and the perfect place in the perfect galaxy for a small, rocky planet orbiting a lonely second generation star to be the perfect home for you and me. Until next time, clear skies! Mark Ritter, who dresses now as in the past, can be reached here. Posted by Administrator at 2001.07.21 08:19 AM \| Comments (0) Globular Clusters The Galaxy > Summer is a great time of the year to be taking a look at globular clusters. If you can get yourself a pair of binoculars, or better, a small telescope, you should go out some time soon on a moonless night and appreciate the subtle beauty of one of these creatures in the dark. Globular clusters, aka "globs" in the astro-biz, are ... well ... clusters of stars that are shaped like ... globules! Scientific terms may not be too poetic, but they're pretty descriptive. Globs aren't just cute wee clusters of stars, however, like grapes on a vine. Oh no! They are menageries of stars that number in the hundreds of thousands! If we lived in a glob we'd have a night sky with tens of thousands of brilliant, bright stars all round. From here, though, they appear only as symmetrical fuzzballs through an eyepiece. But their descriptive moniker doesn't explain why they are the way they are or even how they got here in the first place. Inquiring minds for the last hundreds of years wanted to know. So inquiring minds found out. As early as the beginning of the 20th century, it was believed that our solar system was the center of the Milky Way Galaxy. But then Harlow Shapley came along. (Yes, Harlow Shapley!) While studying the distribution of globs around the skies Shapley realized that they aren't hovering around our system; they seem to be hanging out in an area way over there in the constellation Sagittarius. He assumed these little clusters were moving about that area because that was the center of the Galaxy. He was right. With that observation, and with more he and his colleagues would make in the next decades, they painted a New Picture of this hugely massive universe we live in and changed the face of astronomy for good. It turned out that globs are not only the most compact groups of stars in our galaxy, they are also its oldest stars, the oldest amongst them being over 10 billion years old! In comparison, our sun is a second or third generation star in the disk of our galaxy and is only a middle-aged 5 billion years old. The latest and best theories say that globular clusters were the first things formed in our galaxy, before it flattened and went spiral leaving the globs to hover about it like bees around a huge flower. Globs, it turns out, are the senior citizen communities of spiral galaxies and as such should be treated with the respect they deserve. You can spot some globs tonight! Go out at about 10 PM, with binoculars or telescope and look directly above you. There is center of the constellation Hercules which is shaped like a keystone. Look for the two keystone stars on the western side. Between them you'll see a fuzzball. That's M13, one of the most stunning globs of all. Now look to the south. See that reddish star to the "right" of Mars? That's Antares in the constellation Scorpius. Just to its right is another fuzzball, the glob dubbed M4. Now look to the "left" about 30 degrees, to the teapot-shaped constellation next door to Scorpius called Sagittarius. Just to the left of the top star of The Teapot is another glob, M22. The heavens have many, many more you can discover for yourself just by carefully scanning the skies. Have fun! There are maps and images awaiting you at firstlightastro.com. Until next time, clear skies and happy hunting! Posted by Administrator at 2001.07. 7 08:22 AM \| Comments (0)
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