The Seven Wonders of the Universe: Part 6



July 30, 2007 at 13:16 pm | Leave a Comment

The Night Sky

In her column in Parade Magazine, a writer named Marilyn vos Savant made a list of “Questions too Funny to Answer.” Some of the questions were truly funny, belying people’s mis-understanding of science. Sad, in a way.

But, the saddest question, one that I didn’t find to be funny at all (and I’m surprised she listed it as “funny) was this: “Where did all the stars go? In the ’50s, the sky was loaded with them.”

It really isn’t even a dumb question. It’s a query that reflects a changed perception of the sky: we’re not seeing as many stars as we used to. Back in the ’50s we didn’t have much light pollution as we do now. Populations were somewhat smaller, and we were scattered more. Less light pollution per square meter, you might say.

Today, we light the night sky up with photonic pollution that tells the universe, “Look here! These people have money to burn!” Because, of course, when we light the night sky unnecessarily, we’re wasting money. And harming the environment in more ways than one.

If you ever have a chance to be in a truly dark-sky site, you’d see why I label the night sky as one of the seven wonders of the universe. To quote David Bowman in 2001: A Space Odyssey,, “My god, it’s full of stars!”

And that gorgeous scattering of distant starlight is what set our minds wondering throughout the centuries. They caused us to wonder about what they were, how they got there, what makes them shine, and what will happen to them in the future. The science of astronomy, followed by astrophysics, augmented by physics, planetary science, atmospheric physics, and so many others, flowed from our wonder about the night sky.





The Seven Wonders of the Universe: Part 5



July 26, 2007 at 14:29 pm | Leave a Comment

Star Death

The Kepler supernova remnant (courtesy Chandra X-Ray Satellite Center).

The Kepler supernova remnant (courtesy Chandra X-Ray Satellite Center).

So, from star birth we get star death. That follows, sure as…um… death and taxes. These things move in cycles. Starbirth regions almost always have some elements created by the deaths of the stars that went before them. Much as dying vegetable matter seeds a field here on Earth with the essential nutrients for the next generation of plants and animals, old stars recycle themselves into interstellar space. The elements they leave behind—carbon, nitrogen, oxygen, on up to silver, gold, and iron, and even the radioactive elements like thorium and uranium—get re-used in newborn stars and planets. It’s a pretty efficient mechanism for the universe to re-create itself through the billions of years it has existed, and it will continue for as long as there are stars to give off material.

Of course, the most famous stardeath sites are supernovae, particularly the kind known as Type 1a, which occur when massive stars explode and hurl their outer layers to interstellar space.

Planetary nebula M2-9, from Hubble Space Telescope. Could our own Sun look like this, four or five billion years from now? Its destined to become a planetary nebula, pushing its atmosphere out to space as it dies.

Planetary nebula M2-9, from Hubble Space Telescope. Could our own Sun look like this, four or five billion years from now? It's destined to become a planetary nebula, pushing its atmosphere out to space as it dies.

There are other ways for stars to die and pass on their “legacy” of elements to the cosmos. The Sun won’t die as a supernova, but it will swell up to become a red giant. Much of its mass will get blown off to space, and THAT mass will also be recycled into new stars a few billions of years from now. There’s evidence that material from several dying stars provided the seed material for the Sun and planets, which puts us and our home world smack in the middle of the cosmic cycle of life and death.

Regions of stardeath are nearly everywhere we look in our own galaxy and in countless other galaxies, too. They look remarkably similar, a testament to how the laws of physics and astrophysics work across time and space.





The Seven Wonders of the Universe: Part 4



July 15, 2007 at 20:18 pm | Leave a Comment

Star Birth

The Pillars of Creation, as seen through Hubble Space Telescope. Here, young stars are forming inside cocoons of gas and dust; someday theyll eat their way out, lighting up more of the cloud that gave them birth.

The Pillars of Creation, seen by Hubble Space Telescope. Here, young stars are forming inside cocoons of gas and dust; someday they'll eat their way out, lighting up more of the cloud that gave them birth.

If you’ve been a reader of this site for long, you probably wondered when I’d get to starbirth in this list of seven cosmic wonders. Wait no longer—here it is! Starbirth is one of the great recycling mechanisms of the cosmos. It takes material that is floating around in interstellar space and, under the right conditions, coalesces that material into a star. The process is incredibly long compared to human life spans. Our own star began forming some 4.6 billion years ago. It will live for another 5 billion years and eventually evolve to a white dwarf star. Before it does, the Sun will swell up to become a giant star, shed most of its mass, and then slowly cool and shrink. All that material that it sheds will populate the interstellar medium, perhaps becoming part of new stars in the distant future. Supernova explosions also return elements to space, and those too will become part of new stars and planets.

Regions of starbirth are nearly everywhere we look in our own galaxy and in countless other galaxies, too. Astronomers study them in just about every wavelength of light possible, although infrared-enabled observatories and instruments have the best chance of peeking into the stellar creches to watch the process of stars being born.

NGC 1333, a cluster of stars being born more than 1,000 light-years away. They are still embedded in the cloud of gas that gave them birth. Left, from Spitzer Space Telescope. Spitzer is able to see through the cloud of gas surrounding these stars to see the cluster hidden within. At right is visible-light view of the same cluster.

NGC 1333, a cluster of stars being born more than 1,000 light-years away. They are embedded in the cloud that gave them birth. Spitzer Space Telescope can see through the cloud of gas to see the cluster hidden within.


The Orion Nebula, as seen by Hubble Space Telescope. Hundreds of young stars are forming here, along with dozens of brown dwarfs, objects too cool to be stars and too hot to be planets.

The Orion Nebula, as seen by Hubble Space Telescope. Hundreds of young stars are forming here, as well as brown dwarfs, objects too cool to be stars and too hot to be planets.

A visible-light view of NGC 1333

The closest starbirth region that most of us have heard about is the Orion Nebula, some 1,500 light-years away in the constellation Orion. If you look closely at the blow-up of this image (far left), you’ll see swirls of clouds, and what look like jets emanating from some of the new stars. Newborn stars are chaotic, and they sculpt their birth nests as they form. They also light up their surroundings, creating reflection nebulae—clouds of gas and dust that glow in the reflected light. However, those clouds also give off infrared light because they’re being heated by the nearby stars. So, I give you a glimpse into the mysterious realms of starbirth, a process that is itself one of the seven wonders of the universe.





The Seven Wonders of the Universe: Part 3



July 13, 2007 at 11:55 am | 2 Comments

The Big Bang

I was watching a documentary program the other day and it kept talking about this “huge explosion that created the universe” and referring to the Big Bang. The writer really should have known better, since I know the person is knowledgeable in astronomy, and presumably this writer knows that the creation event really was NOT an explosion. Yet, he/she persisted in using an incorrect term, presumably because “explosion” sounds more dramatic and exciting than “the beginning of expansion of space and time.” And, to be somewhat fair, it is pretty difficult to illustrate the event, so artists just keep on building these flashy explosions and point to them as what the Big Bang might have been like. It may be easy, but it’s not quite correct.

So, what was the Big Bang?

The Big Bang was the beginning of the expansion of space and time. Period. Current theories about this era in cosmic history says little about what was going on before it occurred, although that Pre-BB time is also a time of intense interest to astrophysicists and cosmologists (scientists who study the physics of the cosmos and its origins).

In a sense, we are still inside the creation event of the universe, being carried along as space expands and the cosmic clock ticks along as it has been doing since T=zero. It’s a story that has taken more 13.7 billion years to unfold, and is still occurring.

The universe began as a tiny point of space filled with seething energy. That space began to expand, carrying the energy with it. Over time, things began to cool down, and the first particles of matter condensed out of the energy cloud that was being carried along by the expansion of space. Those particles begat atoms, and molecules, and eventually the building blocks of stars and galaxies.

The microwave sky, showing the last echoes of radiation from the creation of the universe. The image reveals 13.7 billion year old temperature fluctuations (shown as color differences) that correspond to the seeds that grew to become the galaxies.

The microwave sky, showing the last echoes of radiation from the creation of the universe. The image reveals 13.7 billion year old temperature fluctuations (shown as color differences) that correspond to the seeds that grew to become the galaxies.

If you want to talk about wonders of the universe, surely its formation from a seething energy “ball” is wondrous. But, more than that, we can actually see flickers from that time in a wash of cool radiation called the Cosmic Microwave Background Radiation.

So, as my third wonder of the universe, I give you a window onto its creation, more than 13.7 billion years agp. Whatever we call it, it’s one of the most intensely interesting topics in astronomy and cosmology today.





The Seven Wonders of the Universe: Part 2



July 10, 2007 at 12:01 pm | Leave a Comment

Earth

The Home Planet

Our home planet

You’d think we’d know all about our home planet. After all, we live on it. And, we do know quite a bit, just from walking its surface, sailing its oceans, and flying in its atmosphere. But, as any traveller knows, distance lends perspective. It gives us new insights into familiar places, simply by virtue of the fact that we are far away and can perceive home as a place “back there.” You see a bigger picture of your hometown when you’re far away from it. And, so it’s the same with our planet.


Voyagers view of Earth from the edge of the solar system.

Voyager's view of Earth from the "edge" of the solar system -- the blue dot in the right-most "ray" of light.

I’ve been working on a project focused on our planet’s climate,and so I keep returning to these pictures taken from well away from Earth’s surface. The first thing you notice is the water. And then, the clouds. Which, in our case, also speak of water, but in droplet form suspended in our atmosphere. Here and there the continents and islands peek out, and if you’re close enough, you can see the lush green of plant life. It’s home, but it’s also part of the larger universe. The same laws of physics and astrophysics that operate across the cosmos govern our solar system and home planet. What we observe here we can try to find elsewhere. And if we do find watery, lifebearing planets elsewhere, we may understand them better simply by virtue of studying our own world from a distance, too. And, in a sense, what we find at THOSE worlds, will also help us understand our own.

Earth is an amazing find in a universe populated mostly with galaxies studded with stars and nebulae. There are other planets out there, and most likely many with water and life. We haven’t found the life-bearing ones yet, but it’s only a matter of time. Until we do, that pale blue dot in the middle of the ray of light on the right is a rarity. It’s also one of my choices for one of the seven wonders of the universe.





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