TFS says that over a hundred comets are traveling in parabolic orbits, implying that they're all moving at escape velocity, the most common term for the concept. Another poster in this thread explains that the paper says nearly parabolic, meaning that they're moving slightly faster than needed to continue back into interstellar space and never be seen again, which sounds much more reasonable because it suggests a range of speeds, not one specific one. If you wrote TFS and left that word out, I wouldn't be bragging about it.
IIRC, comet Hale-Bopp was discovered when it was somewhere out near Saturn's orbit.
I'm not sure, but that sounds about right. In any event, though it wasn't discovered while it was still in the Kuiper Belt, when it would have been too faint to get accurate enough data to calculate the orbit very well.
My concern is (or was, by this point) that the eccentricity of the orbit depends, in part, on the object's velocity. Unless it's travelling at least at escape speed (to use your pedantry) the orbit must be elliptical, with an eccentricity of less than one; if it's greater than escape, the orbit will be hyperbolic, (greater than one) and if it's exactly at the escape speed/velocity, it will move in a parabola. (exactly one) Given that TFS states (wrongly) that there were at least 100 comets in parabolic orbits, the idea of so many comets having exactly the right velocity/speed for that seemed improbable. Now, of course, I know that TFS misquoted the paper, which explains the oddity.
Yes, because orbits with eccentricities greater than one have hyperbolic orbits. However, orbits with an eccentricity of exactly one have parabolic orbits and also don't stick around. My concern had to do with the fact that there looked like there were an unreasonable number of comets with parabolic orbits, but another poster explained that the paper's authors used the words "nearly parabolic," which is far more believable for me.
In other papers these same researchers use the term "near-parabolic" for this same class of comets...
OK, thanx. That clears everything up for me. It was just a case of sloppy reporting by somebody who didn't quite understand the article enough to see how much of a difference that one word makes.
My understanding is that any comet that originates in the Kupier belt will be in a highly elliptical orbit, and that by the time we can get clear enough observations to calculate that orbit, the comet will be much closer, possibly even within Pluto's and/or Neptune's orbit, but like you, I'm no professional.
Either you didn't understand what I meant, or you explained the situation poorly. I've no problem whatsoever with there being large numbers of interstellar visitors, or with recalculations of the obits of old comets revealing more of them. What bothers me is the large number of observed comets with velocities close enough to escape velocity to have a parabolic orbit; I'd expect most, if not almost all of them to have hyperbolic orbits.
It's been decades since I studied this, and most of the neurons I used to store the details have long since been recycled, but I do remember a little bit about orbital mechanics. If an object's velocity is lower than escape velocity, it's in an elliptical orbit, and if it's above, the orbit's hyperbolic. You only get a parabolic orbit if it's traveling exactly at escape velocity. OK, yes, I understand that there are limits to how precise our measurements are and that leads to a margin of error in the calculated orbit, but I can't help but think that there's something wrong when there are hundreds of comets discovered since 1950 with calculated orbits at exactly escape velocity, as close as we can calculate it. What I wonder is why it took astronomers this long to start checking their figures and finding all of these mistakes. Of course, they might just have been too busy to recheck all of those figures, but still, I'd like to find out.
Or it could be that they need to make their quota of women, minorities or robotic workers.
Or, it could be that they have somebody like me in mind. I'm a senior citizen, i'm a veteran and I'm partially disabled, allowing me to fill three quotas all by myself. And, if there's a quota for people who's disability is service connected, that's a fourth, right there. If I weren't also retired, I could probably hold down a good job doing nothing more than filling quotas.
Actually, in much of California, home owners are required to clear the brush around their property every year, with a deadline for getting it done. If they don't, the county comes out, does the clearance and bills the homeowner about twice what it would have cost to get the work done on time. I know, because I spent several years in an area that needed annual clearance, and I've seen some of the bills that were sent to neighbors who didn't bother to do it themselves.
The text I quoted says that "Reality TV is entertaining at first, purely because of shock value." While I grant that this must be true in some cases, I was pointing out that there are many reality shows out there with zero shock value. Clearly, in your case, it's simply assuming that since you don't watch these shows, they must be terrible. You really need to expand your horizons and find out that there's more good stuff out there than you thought.
Reality TV is cheap to make. Entertaining, at first, purely because of shock value.
My sister and I (both retired) share a home. She's hooked on TV shows about people buying and remodelling homes. Where's the shock value in that? She also loves holiday baking competitions on the Food Network; again, no shock. OK, I'll grant it that sometimes there's a bit of a shock on Chopped, or some similar show when somebody's eliminated that you didn't expect, but that's about it. I'm sure that there must be reality shows out there specializing in shock value, but that's not what we find entertaining, so we never watch any of them.
Indeed he is, and by a convenient coincidence, his voice always reminds me of another voice actor who did some great narration, Sterling Holloway, the original voice of Winnie the Pooh.
Yup! When I read what Gnome 3 was going to be like I started looking for a different DE. By the time it came out I was using Xfce4 and I've never regretted it.
I grew up in California, just like the OP, but recently moved to Colorado, where I just had my first White Halloween. My point, which obviously went over your head, is that if sunset is at 4:30 PDT, as it is in most of Southern California in mid winter, setting the clock forward so that sunset's at 5:30 won't be much help, especially as it gets cold (by California standards, of course) that time of year so that even if there's enough light for surfing it's probably too cold.
So you're able to get off of work an hour earlier in the winter? That's nice, but most people don't have that choice. Oh, and by the way, it's "spring forward, fall back" because you turn your clock back in an hour in the fall, not an hour forward. I know that you're from California, but so am I and I never had any trouble keeping that straight.
My preference would be to just keep DST all year round, because it would give me an extra hour in the afternoon to hang out at the beach and maybe surf.
And how's that going to work for you in mid winter, when sunset is at about 4:30 PM PDT? You can't get extra use from sunshine that isn't there, you know, as the country learned when they tried going to DST year round from 1973-1975.
I recently moved to a town in Colorado, with a population of about 9,000. Before I got my home Internet set up, I could connect through the local library, or if I needed it later in the evening, there are several fast food outlets with WiFi. Sure, it's not as convenient as having it at home, but it's not like you're completely cut off.
What makes you think that tech support's the only thing I've done? I've been a pizza cook, a baker, a coder, been a caregiver for a diabetic who'd gone blind and a number of other things. Tech support just happens to be what I was doing in my mid 50's.
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Same here where I live. We also had a white Halloween. Alas, that's just local weather and doesn't mean diddly-squat on a global level.
Nice idea, but there's one big problem with it. The people who need it the most are the least likely to use it.
TFS says that over a hundred comets are traveling in parabolic orbits, implying that they're all moving at escape velocity, the most common term for the concept. Another poster in this thread explains that the paper says nearly parabolic, meaning that they're moving slightly faster than needed to continue back into interstellar space and never be seen again, which sounds much more reasonable because it suggests a range of speeds, not one specific one. If you wrote TFS and left that word out, I wouldn't be bragging about it.
IIRC, comet Hale-Bopp was discovered when it was somewhere out near Saturn's orbit.
I'm not sure, but that sounds about right. In any event, though it wasn't discovered while it was still in the Kuiper Belt, when it would have been too faint to get accurate enough data to calculate the orbit very well.
My concern is (or was, by this point) that the eccentricity of the orbit depends, in part, on the object's velocity. Unless it's travelling at least at escape speed (to use your pedantry) the orbit must be elliptical, with an eccentricity of less than one; if it's greater than escape, the orbit will be hyperbolic, (greater than one) and if it's exactly at the escape speed/velocity, it will move in a parabola. (exactly one) Given that TFS states (wrongly) that there were at least 100 comets in parabolic orbits, the idea of so many comets having exactly the right velocity/speed for that seemed improbable. Now, of course, I know that TFS misquoted the paper, which explains the oddity.
Yes, because orbits with eccentricities greater than one have hyperbolic orbits. However, orbits with an eccentricity of exactly one have parabolic orbits and also don't stick around. My concern had to do with the fact that there looked like there were an unreasonable number of comets with parabolic orbits, but another poster explained that the paper's authors used the words "nearly parabolic," which is far more believable for me.
In other papers these same researchers use the term "near-parabolic" for this same class of comets...
OK, thanx. That clears everything up for me. It was just a case of sloppy reporting by somebody who didn't quite understand the article enough to see how much of a difference that one word makes.
My understanding is that any comet that originates in the Kupier belt will be in a highly elliptical orbit, and that by the time we can get clear enough observations to calculate that orbit, the comet will be much closer, possibly even within Pluto's and/or Neptune's orbit, but like you, I'm no professional.
Either you didn't understand what I meant, or you explained the situation poorly. I've no problem whatsoever with there being large numbers of interstellar visitors, or with recalculations of the obits of old comets revealing more of them. What bothers me is the large number of observed comets with velocities close enough to escape velocity to have a parabolic orbit; I'd expect most, if not almost all of them to have hyperbolic orbits.
It's been decades since I studied this, and most of the neurons I used to store the details have long since been recycled, but I do remember a little bit about orbital mechanics. If an object's velocity is lower than escape velocity, it's in an elliptical orbit, and if it's above, the orbit's hyperbolic. You only get a parabolic orbit if it's traveling exactly at escape velocity. OK, yes, I understand that there are limits to how precise our measurements are and that leads to a margin of error in the calculated orbit, but I can't help but think that there's something wrong when there are hundreds of comets discovered since 1950 with calculated orbits at exactly escape velocity, as close as we can calculate it. What I wonder is why it took astronomers this long to start checking their figures and finding all of these mistakes. Of course, they might just have been too busy to recheck all of those figures, but still, I'd like to find out.
Or it could be that they need to make their quota of women, minorities or robotic workers.
Or, it could be that they have somebody like me in mind. I'm a senior citizen, i'm a veteran and I'm partially disabled, allowing me to fill three quotas all by myself. And, if there's a quota for people who's disability is service connected, that's a fourth, right there. If I weren't also retired, I could probably hold down a good job doing nothing more than filling quotas.
Actually, in much of California, home owners are required to clear the brush around their property every year, with a deadline for getting it done. If they don't, the county comes out, does the clearance and bills the homeowner about twice what it would have cost to get the work done on time. I know, because I spent several years in an area that needed annual clearance, and I've seen some of the bills that were sent to neighbors who didn't bother to do it themselves.
The text I quoted says that "Reality TV is entertaining at first, purely because of shock value." While I grant that this must be true in some cases, I was pointing out that there are many reality shows out there with zero shock value. Clearly, in your case, it's simply assuming that since you don't watch these shows, they must be terrible. You really need to expand your horizons and find out that there's more good stuff out there than you thought.
Reality TV is cheap to make. Entertaining, at first, purely because of shock value.
My sister and I (both retired) share a home. She's hooked on TV shows about people buying and remodelling homes. Where's the shock value in that? She also loves holiday baking competitions on the Food Network; again, no shock. OK, I'll grant it that sometimes there's a bit of a shock on Chopped, or some similar show when somebody's eliminated that you didn't expect, but that's about it. I'm sure that there must be reality shows out there specializing in shock value, but that's not what we find entertaining, so we never watch any of them.
Indeed he is, and by a convenient coincidence, his voice always reminds me of another voice actor who did some great narration, Sterling Holloway, the original voice of Winnie the Pooh.
I don't have to, I remember watching it first run. And, as it happens, I am not a number, I am a free man! Be seeing you...
Yup! When I read what Gnome 3 was going to be like I started looking for a different DE. By the time it came out I was using Xfce4 and I've never regretted it.
Considering that I was just guessing about how early sunset gets in LA, that's not bad.
I rather think I do, after living in California for almost seventy years. What you're nitpicking was a typo.
You're one of the lucky ones, then. Most people spend eight or more hours working on at least five days out of every seven.
I grew up in California, just like the OP, but recently moved to Colorado, where I just had my first White Halloween. My point, which obviously went over your head, is that if sunset is at 4:30 PDT, as it is in most of Southern California in mid winter, setting the clock forward so that sunset's at 5:30 won't be much help, especially as it gets cold (by California standards, of course) that time of year so that even if there's enough light for surfing it's probably too cold.
So you're able to get off of work an hour earlier in the winter? That's nice, but most people don't have that choice. Oh, and by the way, it's "spring forward, fall back" because you turn your clock back in an hour in the fall, not an hour forward. I know that you're from California, but so am I and I never had any trouble keeping that straight.
My preference would be to just keep DST all year round, because it would give me an extra hour in the afternoon to hang out at the beach and maybe surf.
And how's that going to work for you in mid winter, when sunset is at about 4:30 PM PDT? You can't get extra use from sunshine that isn't there, you know, as the country learned when they tried going to DST year round from 1973-1975.
I recently moved to a town in Colorado, with a population of about 9,000. Before I got my home Internet set up, I could connect through the local library, or if I needed it later in the evening, there are several fast food outlets with WiFi. Sure, it's not as convenient as having it at home, but it's not like you're completely cut off.
What makes you think that tech support's the only thing I've done? I've been a pizza cook, a baker, a coder, been a caregiver for a diabetic who'd gone blind and a number of other things. Tech support just happens to be what I was doing in my mid 50's.