4/29/07 – 5/5/07
by C. Zaitz
The news is that astronomers have found a new planet orbiting a distant star. Astronomers have been finding planets in distant solar systems for decades, but usually the planets they discover are huge, more like Jupiter on steroids than anything earth-like. With better telescopes and more research, we are beginning to see the smaller planets. One in particular is being heralded as a “Goldilocks” planet, not too big, not too small, nor too cold, nor too hot. A “just right” planet that could possibly harbor liquid water, pretty sunsets, or even life. At least that’s the theory.
Sometimes we refer to our neighboring planets as having the “Goldilocks syndrome.” Mars and Venus are our cosmic neighbors, and together, we three planets all orbit within a distance from the sun called the “habitable zone,” where the amount of solar radiation reaching the surface is conducive for reasonable temperatures. So why did earth alone develop life, so prolifically and thoroughly that not even cataclysmic events could completely wipe it out? And what went wrong with our neighbors?
Venus is a study in what can go wrong with a nice planet. Venus and earth have plenty in common. They are very close in size, composition and their distance from the sun. However, Venus ended up with a very big problem: a runaway greenhouse effect. The effect of atmosphere trapping solar radiation and making a planet warmer than it should be is common- earth and Mars also have it. However, perhaps because it gets more solar radiation or because it had more carbon dioxide in its atmosphere, Venus is in a vicious cycle where its thick clouds trap nearly all the sunlight coming in. It simply cannot cool itself off. As we raise the level of certain gasses in our own atmosphere, we run the risk of having our greenhouse effect go astray. The current warming trend of our planet is a giant red flag that we are indeed starting a process that we would not be able to stop, much less reverse.
Mars, due to its further distance from the sun or its diminutive size, has too little atmosphere, and thus too little greenhouse effect. It is too cold on the surface of Mars for water to exist in liquid form, so it ended up a dry, cold desert-like planet. We know that Mars once was warmer and are convinced that water used to flow, but unless the conditions are just right, a planet goes awry and climate changes ensue.
The newly discovered Goldilocks planet is orbiting a red dwarf star called Gliese 581, about 20 light years away. The planet is heavier than earth, with a rocky surface and most likely liquid water. That’s a lot of information about this planet, since the data they gathered is mostly about how Gliese 581 wobbles. From this wobble, astronomers can glean information about what is going around the star to make it wobble. They infer size, distance, and even composition from the wobble. They have surmised that Gliese’s planet may be very much like earth, perhaps a “just right” place where water and life could exist. However, as we look at our neighboring planets, we see a lot of variation in a planet’s fate. It will be interesting to learn more about these extra-solar planets. Even if we don’t find life, perhaps we will find answers to how planets behave, giving us insight to our own problems and possible solutions.
Until next week, my friends, enjoy the view.
Wednesday, April 25, 2007
Tuesday, April 24, 2007
Super Massive Black Holes
4/22/07 – 4/28/07
by C. Zaitz
One of the more eyebrow-raising bits of gossip heard in astronomy circles is that most galaxies, even our own, contain a super massive black hole at their cores. A super massive black hole is much heavier than a garden variety stellar black hole, which can weigh as little as one and a half suns or as much as 14 suns. That may not sound spectacular, but a black hole with the mass of 10 suns could fit into the city of Detroit. The mass of a black hole is directly related to its size, so the heavier it is, the bigger it is. But how massive is super massive?
The monster black holes we find in the centers of galaxies tend to range in mass from a hundred thousands suns to tens of billions of suns. Some scientists suggest that they started out the same way stellar-sized holes do, but over long periods of time grew larger and larger from consuming the available material in the center of the galaxy. It seems more likely that these black holes, like the one in the middle of our galaxy, formed from a large cloud of collapsing gas, creating a massive central star, some hundreds of thousands of solar masses, which then collapsed (with no supernova) to form a gigantic black hole. Since that time it has been eating everything close enough to be drawn in. Don’t worry, though; we are very, very far from the center of our galaxy, and not in the least affected by it.
We noted that the mass of the hole is directly related to its size, but it turns out that the density of a black hole is inversely related to its mass. The bigger the original star, the less dense it needs to be to become a black hole. Super massive black holes can actually be about as dense as water, since they are so very massive. And the event horizon, the place beyond which we lose sight of you as you swirl in, is so far from the singularity at the center that a trip into the super massive black hole would take enough time to allow you to ponder your fate. In fact, scientists think that the tidal forces normally so very strong near a black hole, strong enough to “spaghettify” you (your atoms are ripped into a long strand of you as you twirl into the hole) are not so strong near the really massive black holes. So your trip into it might be somewhat non-eventful, if not pleasant. That is, if you were to be so foolish to be near such a black hole. Lest we forget, there are many dangerous things about black holes, not the least of which is the torrent of X-rays and gamma rays flooding out of the accretion disk. This is the plate of material feeding into the black hole, and it really does look like a big, gassy plate, serving up the special of the day.
If you’d like to try to see the black hole at the center of our galaxy, you will have to imagine it, for it’s shrouded by millions of stars, clouds of gas and dark nebula forming a curtain in front of it. Even if there was no curtain, you’d still be hard pressed to see it, since no light can escape their gravitational pull, making them earn their nefarious reputations of the invisible gas-eating monsters in space.
Until next week, my friends, enjoy the view.
by C. Zaitz
One of the more eyebrow-raising bits of gossip heard in astronomy circles is that most galaxies, even our own, contain a super massive black hole at their cores. A super massive black hole is much heavier than a garden variety stellar black hole, which can weigh as little as one and a half suns or as much as 14 suns. That may not sound spectacular, but a black hole with the mass of 10 suns could fit into the city of Detroit. The mass of a black hole is directly related to its size, so the heavier it is, the bigger it is. But how massive is super massive?
The monster black holes we find in the centers of galaxies tend to range in mass from a hundred thousands suns to tens of billions of suns. Some scientists suggest that they started out the same way stellar-sized holes do, but over long periods of time grew larger and larger from consuming the available material in the center of the galaxy. It seems more likely that these black holes, like the one in the middle of our galaxy, formed from a large cloud of collapsing gas, creating a massive central star, some hundreds of thousands of solar masses, which then collapsed (with no supernova) to form a gigantic black hole. Since that time it has been eating everything close enough to be drawn in. Don’t worry, though; we are very, very far from the center of our galaxy, and not in the least affected by it.
We noted that the mass of the hole is directly related to its size, but it turns out that the density of a black hole is inversely related to its mass. The bigger the original star, the less dense it needs to be to become a black hole. Super massive black holes can actually be about as dense as water, since they are so very massive. And the event horizon, the place beyond which we lose sight of you as you swirl in, is so far from the singularity at the center that a trip into the super massive black hole would take enough time to allow you to ponder your fate. In fact, scientists think that the tidal forces normally so very strong near a black hole, strong enough to “spaghettify” you (your atoms are ripped into a long strand of you as you twirl into the hole) are not so strong near the really massive black holes. So your trip into it might be somewhat non-eventful, if not pleasant. That is, if you were to be so foolish to be near such a black hole. Lest we forget, there are many dangerous things about black holes, not the least of which is the torrent of X-rays and gamma rays flooding out of the accretion disk. This is the plate of material feeding into the black hole, and it really does look like a big, gassy plate, serving up the special of the day.
If you’d like to try to see the black hole at the center of our galaxy, you will have to imagine it, for it’s shrouded by millions of stars, clouds of gas and dark nebula forming a curtain in front of it. Even if there was no curtain, you’d still be hard pressed to see it, since no light can escape their gravitational pull, making them earn their nefarious reputations of the invisible gas-eating monsters in space.
Until next week, my friends, enjoy the view.
Wednesday, April 11, 2007
Black, Black Holes
4/15/07 – 4/21/07
by C. Zaitz
One of the strangest, most compelling objects in the universe are black holes. The idea that something can be so powerful, so destructive, and yet invisible to us is very compelling. Ever since they were first speculated to exist, we have been searching the skies for the invisible monsters, the star-eating, gas-sucking anomalies of nature.
At first, it was very hard to find black holes. You have to get creative; you have to find something that the black hole is affecting. It’s like looking for the skunk that gets into your garbage every night. You can’t see it; it’s dark and you’re looking in the night, but skunks certainly leave clues behind. So we try to “sniff out” black holes, and look for the destruction they cause.
One of the best indicators of the presence of a black hole is a binary star system that emits X-rays. Binary star systems are quite common in the galaxy, and it turns out that often, one star is much bigger than the other. Big stars, like Elvis, tend to burn very brightly and burn out quickly. When massive stars die, they often become black holes. The companion star still orbits the “hole” left behind, but if material from the companion star happens to get too close to the black hole, it will get swirled in and “eaten,” streaming out X-rays as tidal forces ionize the infalling gas. We see the X-rays, and can begin to pinpoint the black hole.
There are different sizes of black holes, but the most familiar are the ones that come from big stars, like the star in the shoulder of Orion called Betelgeuse (commonly pronounced “beetle-juice” to the delight of untold numbers of elementary students.) Betelgeuse is said to be bigger than the orbit of Mars. When such a massive star dies, it generally ends up in one of the most spectacular events in the universe, a supernova explosion. Most of the mass of the star is violently distributed into space as giant clouds of hot, colorful gas. But the core of the star remains, is still very massive, and has no means to keep it from collapsing. It begins a journey that no force in nature can hinder, and it only stops until all that once was the star is found in one single point - the singularity.
One curious thing about black holes is their affinity for infinity. Laws of physics, as we know them, start to get wobbly when we get close to the “singularity.” This is the point at which what used to be matter has collapsed to a single point. This is very hard to imagine. How can a lot of stuff, with a lot of mass and gravity, collapse into a single point? And how big is that point?
Einstein’s theory of general relativity tells us that at the singularity, all the core’s mass is compressed into a space with zero volume, while its density and gravity are infinitely big! But quantum physics, with its uncertainly principle, says more reasonably that it’s a very large amount of matter squeezed into the smallest possible amount of space. Still, it’s a pretty quirky concept. Perhaps that’s why they are so very interesting.
Next week, we will talk about the even more curious super-massive black holes. Meanwhile, enjoy lovely Venus in the sunset and Saturn crossing the southern skies all night long.
Until next week, my friends, enjoy the view.
by C. Zaitz
One of the strangest, most compelling objects in the universe are black holes. The idea that something can be so powerful, so destructive, and yet invisible to us is very compelling. Ever since they were first speculated to exist, we have been searching the skies for the invisible monsters, the star-eating, gas-sucking anomalies of nature.
At first, it was very hard to find black holes. You have to get creative; you have to find something that the black hole is affecting. It’s like looking for the skunk that gets into your garbage every night. You can’t see it; it’s dark and you’re looking in the night, but skunks certainly leave clues behind. So we try to “sniff out” black holes, and look for the destruction they cause.
One of the best indicators of the presence of a black hole is a binary star system that emits X-rays. Binary star systems are quite common in the galaxy, and it turns out that often, one star is much bigger than the other. Big stars, like Elvis, tend to burn very brightly and burn out quickly. When massive stars die, they often become black holes. The companion star still orbits the “hole” left behind, but if material from the companion star happens to get too close to the black hole, it will get swirled in and “eaten,” streaming out X-rays as tidal forces ionize the infalling gas. We see the X-rays, and can begin to pinpoint the black hole.
There are different sizes of black holes, but the most familiar are the ones that come from big stars, like the star in the shoulder of Orion called Betelgeuse (commonly pronounced “beetle-juice” to the delight of untold numbers of elementary students.) Betelgeuse is said to be bigger than the orbit of Mars. When such a massive star dies, it generally ends up in one of the most spectacular events in the universe, a supernova explosion. Most of the mass of the star is violently distributed into space as giant clouds of hot, colorful gas. But the core of the star remains, is still very massive, and has no means to keep it from collapsing. It begins a journey that no force in nature can hinder, and it only stops until all that once was the star is found in one single point - the singularity.
One curious thing about black holes is their affinity for infinity. Laws of physics, as we know them, start to get wobbly when we get close to the “singularity.” This is the point at which what used to be matter has collapsed to a single point. This is very hard to imagine. How can a lot of stuff, with a lot of mass and gravity, collapse into a single point? And how big is that point?
Einstein’s theory of general relativity tells us that at the singularity, all the core’s mass is compressed into a space with zero volume, while its density and gravity are infinitely big! But quantum physics, with its uncertainly principle, says more reasonably that it’s a very large amount of matter squeezed into the smallest possible amount of space. Still, it’s a pretty quirky concept. Perhaps that’s why they are so very interesting.
Next week, we will talk about the even more curious super-massive black holes. Meanwhile, enjoy lovely Venus in the sunset and Saturn crossing the southern skies all night long.
Until next week, my friends, enjoy the view.
Thursday, April 05, 2007
Orbiting Fun
4/1/07 – 4/7/07
One of my favorite websites is “Astronomy Picture of the Day” (APOD) - the images are just amazing. One recent image depicted the very slim crescent moon hanging above the blue-skied horizon of the earth. It was taken by the astronauts on the space station. I often forget that there are astronauts floating above the earth looking down on us every ninety minutes or so. In their free time they like to take pictures of the earth, and the one they took of the crescent moon is beautifully dream-like. Well, at least it made me day-dream when I saw it.
I thought about how fun it might be to toss little pebbles out the window and watch them burn up as they fall through the air and descend to earth. I would be creating my own meteors, and how fun is it that people on the earth below would look up and see my meteor shower. How many little children would be making wishes on the “falling stars” I was tossing down? Wouldn’t it be nice if there was a front porch on the International Space Station for visitors who are lucky enough to go up there? What a view from that porch swing!
Obviously I’m amusing myself with fanciful thoughts of being in orbit, but I bet someday it will come true. Why not? People pay lots of money for all sorts of exotic vacations, but what could be more exotic than a few weeks aboard the space station? Of course, it being a scientific endeavor, and being rather on the dangerous end of things, one should probably come up with a scientific experiment or two to make it worthwhile. It can’t be all solar-tanning windows and zero-g foot rubs. I think I would experiment with different fluids and how they behaved in space. I would be sure to bring along six-packs of various fluids, and perhaps some pretzels to interact with the fluids. I’d be interested to study the formation of bubbles on carbonated beverages floating in microgravity. I’d also study how the human body reacts to these carbonated beverages. I’ve seen pictures of the astronauts floating giant bubbles of liquid around the cabin, dodging and ducking to catch them in their mouths. I think that would be pretty fun, and I’m sure there’s some scientific value in it.
While I was up on the porch of the Space Station, I would be sure to take lots of photos. I’d try to capture a pebble falling through the air. I think it would look like a pebble for awhile, and then it would start to glow, and then I’d see a little blaze and then would see it no more. That’s my theory, but it would be fun to prove it. That’s what science is all about, right?
There is science going on up there. The astronauts have a barrage of experiments they tend, from growing protein crystals to live tissue cells. Life in low gravity is very different than anything the human body is used to. If we ever want to make trips to Mars or other planets, we need to learn how to counteract the atrophy of our muscles and the weakening of our bones. We have to learn how to maneuver in centrifuges which can simulate the effects of gravity. There’s a lot to learn about living in space, but I know that I’d be on the list of volunteers to spend spring break in orbit!
Until next week, my friends, enjoy the view.
One of my favorite websites is “Astronomy Picture of the Day” (APOD) - the images are just amazing. One recent image depicted the very slim crescent moon hanging above the blue-skied horizon of the earth. It was taken by the astronauts on the space station. I often forget that there are astronauts floating above the earth looking down on us every ninety minutes or so. In their free time they like to take pictures of the earth, and the one they took of the crescent moon is beautifully dream-like. Well, at least it made me day-dream when I saw it.
I thought about how fun it might be to toss little pebbles out the window and watch them burn up as they fall through the air and descend to earth. I would be creating my own meteors, and how fun is it that people on the earth below would look up and see my meteor shower. How many little children would be making wishes on the “falling stars” I was tossing down? Wouldn’t it be nice if there was a front porch on the International Space Station for visitors who are lucky enough to go up there? What a view from that porch swing!
Obviously I’m amusing myself with fanciful thoughts of being in orbit, but I bet someday it will come true. Why not? People pay lots of money for all sorts of exotic vacations, but what could be more exotic than a few weeks aboard the space station? Of course, it being a scientific endeavor, and being rather on the dangerous end of things, one should probably come up with a scientific experiment or two to make it worthwhile. It can’t be all solar-tanning windows and zero-g foot rubs. I think I would experiment with different fluids and how they behaved in space. I would be sure to bring along six-packs of various fluids, and perhaps some pretzels to interact with the fluids. I’d be interested to study the formation of bubbles on carbonated beverages floating in microgravity. I’d also study how the human body reacts to these carbonated beverages. I’ve seen pictures of the astronauts floating giant bubbles of liquid around the cabin, dodging and ducking to catch them in their mouths. I think that would be pretty fun, and I’m sure there’s some scientific value in it.
While I was up on the porch of the Space Station, I would be sure to take lots of photos. I’d try to capture a pebble falling through the air. I think it would look like a pebble for awhile, and then it would start to glow, and then I’d see a little blaze and then would see it no more. That’s my theory, but it would be fun to prove it. That’s what science is all about, right?
There is science going on up there. The astronauts have a barrage of experiments they tend, from growing protein crystals to live tissue cells. Life in low gravity is very different than anything the human body is used to. If we ever want to make trips to Mars or other planets, we need to learn how to counteract the atrophy of our muscles and the weakening of our bones. We have to learn how to maneuver in centrifuges which can simulate the effects of gravity. There’s a lot to learn about living in space, but I know that I’d be on the list of volunteers to spend spring break in orbit!
Until next week, my friends, enjoy the view.
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