Heh. Well, I was careful to state that *the light we see from the cluster left 9.6 billion years ago*. When you start talking about the age "now" and distance traveled and all that, things get sticky quickly. Relativity makes a mess of our sense of "now".
The paper in this article is pretty interesting, but I don't think it explains the newest features seen in these gullies; the way they terminate in the sand looks more like a liquid flow than solid. I suspect that the authors can explain many gullies on Mars, but not all the gullies. There may be more than one mechanism at work here!
It's a 10 inch mirror. I owned a 'scope like that for over 20 years, and it's a pretty decent instrument. It looked like a water heater; a foot across and two yards long.
As someone noted above, I'm now very sure this was a natural piece of cosmic debris, a chunk of asteroid or something similar. I posted a wrapup with my thoughts.
Our supermassive black hole is quiescent right now, more or less, because it's not feeding. But there are a number of events that can dump gas into it. Collisions are the best way, but we're not colliding with anything right now massive enough to do the deed. However, I have read that there is a large repository of gas not too far from the BH that could fall in sometime in the next 30 million years or so. Not too much to worry about now, but it could fire things up a bit.
However, our BH isn't terribly massive as these things go (4 million times the Sun's mass) and there is some correlation between BH mass and activity strength when it occurs. Also, it's safe to assume that any jets of energy and matter would head up and out of the disk. There's a lot of gas and dust between us and it, so we're probably pretty safe.
I agree. It's very easy now to find, for example, astronomy news on blogs where the author knows what they are talking about (cough cough). Universe Today is a great example, and there are many others. The mainstream media have shot themselves in the foot over the past few years; very few have any dedicated science reporters, but the public *likes* science stories. So folks turn to teh intertoobs, and I for one welcome our new public overlords.
At the bottom of the blog post I put a link to the cached article, and I took a snapshot of it which is on my Flickr account. It's all linked on the blog.
There are lots of reasons to do this. As I mention in my comment above, we are just now, just barely, getting to the point where our catalog of planets is big enough where we can actually start looking at statistics. That in and of itself is amazing! When I got into graduate school, not that long ago, we knew of no extrasolar planets, and by the time I got my degree the first had been discovered. Now there are over 200!
We knew very little about planetary formation, and now we see it happening! And we can see the results, look at systems with different ages, see how our own solar system may change over time. How do stars with planets differ form those that are without? What did our early solar system look like? How does that affect the origin of life, or the future of our planet?
This research costs very little, so it's an easy investment. And beware of the false dichotomy, the either/or fallacy: there is money enough to investigate much of the Universe and the world around us. We just have to decide to do it.
Well, thanks for the link love. I don't mean to downplay the discovery; it's very cool, and we're one-by-one building an actual catalog of extrasolar planets, which means we can do taxonomy on them. How cool is that? I just want people to understand that there ain't nothing Earthlike about the planet, so that we don't get people running around overblowing this news.
That's an astute question. Perfect spheres are hard to come by in astronomy, though they're out there (Abell 39 is probably the best example: http://antwrp.gsfc.nasa.gov/apod/image/0101/abell3 9_wiyn_big.jpg). The famous Ring Nebula (http://antwrp.gsfc.nasa.gov/apod/ap060625.html) is an object that people thought was a ring, but it turns out to be barrel-shaped and pointed at us. That happened a lot. Bipolar objects are very common, since lots of objects either spin or have disks, which shapes the outflow into two lobes of some kind.
Oh, I prefer vodka or tequila, but the point is still true.:)
It's not so much that we talk conservatively, as it is that people tend to tale whatever small thing you say and run with it. At least in my case that's true! I try to lay things out pretty clearly if I can. I think Eta has maybe a few hundred years left before it blows, tops, but others might give it longer. The point is, *we don't know*.
But it'll be cool when it does explode. Woohoo!
There are several forces that direct the outflow of an explosion. In this case, it's the rotation of the star coupled with its magnetic fields. When the core collapses, it forms a black hole. The inner parts of the star collapse down too, forming a flattened disk around the BH. The disk rotates quickly, and has ferocious magnetic fields. It's also incredibly hot. This forces material outward, along the poles of the disk. Two beams of energy and matter erupt out, forming what we call a gamma-ray burst. We're pretty sure this will be along the same axis as those two lobes which blew out in the 1800s. So they'll miss us. If the star explodes as a regular old supernova, it's too far away to do any damage; they have to be withing about 100 light years to harm us. I have references for all this, but I won't list them here. I'm writing a chapter in my next book about it...:-)
Heh-- I thought of Jinx as well, but my first thought was actually Mesklin. However, Mesklin was a much, much higher gravity world!
Interestingly, if the planet is covered in an ocean, animals could still get pretty big due to buoyancy.
I can confirm this: I just saw the comet at 10:30 a.m. local time Sunday morning!
Incredible. In all my years as an astronomer I have never seen anything like this. Using my binoculars I could easily spot it 5 degrees from the Sun. I'm trying to get video now, but it's so close it will be difficult.
I made a videoblog about this the other day. I'll have to update it now!
I want to see hi-res images of the "banyan trees" as well as the "spiders" at the south pole. There are some pretty good guesses on what these are, but half-meter resolution images might put the speculation to rest.
Heh. Oval BA was in my "Runners Up" list. If I have time tonight I'll put up a second page with 5 more images I like, though more likely it'll be next week.
Actually, this is not quite the case. My page links to others which explain the illusion (and where is my page rude?) as a product of the Ponzo Illusion coupled with the way we perceive the sky as a bowl shape. The horizon as a foreground object doesn't have anything to do with it. It is a reference point against which we judge the shape of the sky, but the misconception itself is that the Moon is being compared to trees and buildings. That's not the case.
I have a whole chapter about the illusion in my book. I won't reprint it here since it's 5000 words, but a good place to get the idea is Donald Simanek's page at http://www.lhup.edu/~dsimanek/3d/moonillu.htm
I'll be updating my own page with a description of my own eventually, but for now I'll just link to those other pages.
I never said I am an authority; however, I am a professional astronomer and I do have a basic grasp of the science. That's why I created the website in the first place: I want people to understand what's what in the field. To do that, I use a popular misconception and show why it's wrong.
Your point about Earthlight is partially valid in a scientific sense, but doesn't really affect the misconception of people confusing the far side of the Moon with a fictional dark side. The whole point is that people don't understand that there is no permanent dark side, but there is a permanent far side.
Talking about Earthlight would be an interesting side issue, but is not the main thrust of my point. Making that the main point would indeed be superficial and narrow. It's nitpicky. And yes, I can be nitpicky too, but it almost always has a purpose.
Slashdot Mirror
Heh. Well, I was careful to state that *the light we see from the cluster left 9.6 billion years ago*. When you start talking about the age "now" and distance traveled and all that, things get sticky quickly. Relativity makes a mess of our sense of "now".
The paper in this article is pretty interesting, but I don't think it explains the newest features seen in these gullies; the way they terminate in the sand looks more like a liquid flow than solid. I suspect that the authors can explain many gullies on Mars, but not all the gullies. There may be more than one mechanism at work here!
I gave up shame ages ago. Helps me sleep at night! /srsly, thx. :)
FWIW, I posted on my blog about this amazing pic from Soichi, explaining it a bit and giving my thoughts.
It's a 10 inch mirror. I owned a 'scope like that for over 20 years, and it's a pretty decent instrument. It looked like a water heater; a foot across and two yards long.
As someone noted above, I'm now very sure this was a natural piece of cosmic debris, a chunk of asteroid or something similar. I posted a wrapup with my thoughts.
Thanks for the link lurv. I did write up an extensive description of this as best I could. It's a weird experiment!
Our supermassive black hole is quiescent right now, more or less, because it's not feeding. But there are a number of events that can dump gas into it. Collisions are the best way, but we're not colliding with anything right now massive enough to do the deed. However, I have read that there is a large repository of gas not too far from the BH that could fall in sometime in the next 30 million years or so. Not too much to worry about now, but it could fire things up a bit. However, our BH isn't terribly massive as these things go (4 million times the Sun's mass) and there is some correlation between BH mass and activity strength when it occurs. Also, it's safe to assume that any jets of energy and matter would head up and out of the disk. There's a lot of gas and dust between us and it, so we're probably pretty safe.
I agree. It's very easy now to find, for example, astronomy news on blogs where the author knows what they are talking about (cough cough). Universe Today is a great example, and there are many others. The mainstream media have shot themselves in the foot over the past few years; very few have any dedicated science reporters, but the public *likes* science stories. So folks turn to teh intertoobs, and I for one welcome our new public overlords.
At the bottom of the blog post I put a link to the cached article, and I took a snapshot of it which is on my Flickr account. It's all linked on the blog.
There are lots of reasons to do this. As I mention in my comment above, we are just now, just barely, getting to the point where our catalog of planets is big enough where we can actually start looking at statistics. That in and of itself is amazing! When I got into graduate school, not that long ago, we knew of no extrasolar planets, and by the time I got my degree the first had been discovered. Now there are over 200! We knew very little about planetary formation, and now we see it happening! And we can see the results, look at systems with different ages, see how our own solar system may change over time. How do stars with planets differ form those that are without? What did our early solar system look like? How does that affect the origin of life, or the future of our planet? This research costs very little, so it's an easy investment. And beware of the false dichotomy, the either/or fallacy: there is money enough to investigate much of the Universe and the world around us. We just have to decide to do it.
Well, thanks for the link love. I don't mean to downplay the discovery; it's very cool, and we're one-by-one building an actual catalog of extrasolar planets, which means we can do taxonomy on them. How cool is that? I just want people to understand that there ain't nothing Earthlike about the planet, so that we don't get people running around overblowing this news.
That's an astute question. Perfect spheres are hard to come by in astronomy, though they're out there (Abell 39 is probably the best example: http://antwrp.gsfc.nasa.gov/apod/image/0101/abell3 9_wiyn_big.jpg). The famous Ring Nebula (http://antwrp.gsfc.nasa.gov/apod/ap060625.html) is an object that people thought was a ring, but it turns out to be barrel-shaped and pointed at us. That happened a lot. Bipolar objects are very common, since lots of objects either spin or have disks, which shapes the outflow into two lobes of some kind.
Oh, I prefer vodka or tequila, but the point is still true. :)
It's not so much that we talk conservatively, as it is that people tend to tale whatever small thing you say and run with it. At least in my case that's true! I try to lay things out pretty clearly if I can. I think Eta has maybe a few hundred years left before it blows, tops, but others might give it longer. The point is, *we don't know*.
But it'll be cool when it does explode. Woohoo!
There are several forces that direct the outflow of an explosion. In this case, it's the rotation of the star coupled with its magnetic fields. When the core collapses, it forms a black hole. The inner parts of the star collapse down too, forming a flattened disk around the BH. The disk rotates quickly, and has ferocious magnetic fields. It's also incredibly hot. This forces material outward, along the poles of the disk. Two beams of energy and matter erupt out, forming what we call a gamma-ray burst. We're pretty sure this will be along the same axis as those two lobes which blew out in the 1800s. So they'll miss us. If the star explodes as a regular old supernova, it's too far away to do any damage; they have to be withing about 100 light years to harm us. I have references for all this, but I won't list them here. I'm writing a chapter in my next book about it... :-)
Heh-- I thought of Jinx as well, but my first thought was actually Mesklin. However, Mesklin was a much, much higher gravity world! Interestingly, if the planet is covered in an ocean, animals could still get pretty big due to buoyancy.
I can confirm this: I just saw the comet at 10:30 a.m. local time Sunday morning! Incredible. In all my years as an astronomer I have never seen anything like this. Using my binoculars I could easily spot it 5 degrees from the Sun. I'm trying to get video now, but it's so close it will be difficult. I made a videoblog about this the other day. I'll have to update it now!
Back when I was working on Hubble, I thought of trying to figure out the cost per pixel per second. That got hard to calculate though. :-)
I want to see hi-res images of the "banyan trees" as well as the "spiders" at the south pole. There are some pretty good guesses on what these are, but half-meter resolution images might put the speculation to rest.
Heh. Oval BA was in my "Runners Up" list. If I have time tonight I'll put up a second page with 5 more images I like, though more likely it'll be next week.
Actually, this is not quite the case. My page links to others which explain the illusion (and where is my page rude?) as a product of the Ponzo Illusion coupled with the way we perceive the sky as a bowl shape. The horizon as a foreground object doesn't have anything to do with it. It is a reference point against which we judge the shape of the sky, but the misconception itself is that the Moon is being compared to trees and buildings. That's not the case. I have a whole chapter about the illusion in my book. I won't reprint it here since it's 5000 words, but a good place to get the idea is Donald Simanek's page at http://www.lhup.edu/~dsimanek/3d/moonillu.htm I'll be updating my own page with a description of my own eventually, but for now I'll just link to those other pages.
I never said I am an authority; however, I am a professional astronomer and I do have a basic grasp of the science. That's why I created the website in the first place: I want people to understand what's what in the field. To do that, I use a popular misconception and show why it's wrong. Your point about Earthlight is partially valid in a scientific sense, but doesn't really affect the misconception of people confusing the far side of the Moon with a fictional dark side. The whole point is that people don't understand that there is no permanent dark side, but there is a permanent far side. Talking about Earthlight would be an interesting side issue, but is not the main thrust of my point. Making that the main point would indeed be superficial and narrow. It's nitpicky. And yes, I can be nitpicky too, but it almost always has a purpose.