A couple of years ago there was a big brouhaha over whether Pluto is a planet. The International Astronomical Union declared that it is not. The controversy has popped up once again, as seen on blogs such as Bad Astronomy, Universe Today and The Planetary Society. The problem arose because when Pluto was discovered in 1930, it was believed to be Planet X, a large planet which was perturbing the orbit of Neptune. Well, better observations proved that there is no such perturbation, and that Pluto is relatively tiny, smaller than our moon. It was unlike all other planets in other ways, as well. Then astronomers started finding similar objects, some of them nearly as large as Pluto, and eventually they found one which was larger. Astronomers such as Neil DeGrasse Tyson had already been disputing Pluto's classification as a planet, and this brought the controversy to a head. Either we had to accept this new object, and possibly many others, as planets, or admit that Pluto is not one.
The problem was that there was no accepted definition of what a planet is. Originally, the Greeks called anything that moved in the sky a planet, which included the star-like Mercury, Venus, Mars, Jupiter and Saturn, as well as the sun and moon, but not the earth. After Copernicus and Galileo showed that most of these orbited the sun, rather than us, the earth was recognized as being a planet, and the sun and moon were recategorized. This worked fine, until a couple of hundred years ago when astronomers accidentally discovered Uranus orbiting far past Saturn, which fit in with the other planets. They wondered why there was a large gap between Mars and Jupiter, and when they looked found something, a small, round body which was recognized as a planet and named Ceres. However, Ceres was tiny compared to other planets, and then other small bodies were found in the same region, which were then reclassified together as "minor planets", or asteroids. Around this time, oddities in the orbit of Uranus led to the discovery of Neptune, making for eight planets.
Inaccurate measurements of Neptune's orbit led to the belief that there must be another large planet, called Planet X. This led to the discovery of Pluto by Clyde Tombaugh in 1930. As with Ceres, after several decades and the discovery of numerous other bodies in the same region, Pluto was demoted. Some people are still unhappy about this, and consider Pluto to be a planet. This all begs the question of what is a planet? It really comes down to semantics. It's easy to classify things when the differences between them are large, but when there is a range of intermediate objects, then the question of where to draw the line becomes rather arbitrary.
The most obvious place to draw the line is on whether the object is round. This would include little Ceres as well as Pluto and a number of objects past Neptune. The problem with this is that there may be a great many small, round objects. (That a planet must be orbiting the sun, and not some other body in the solar system, is agreed by everyone; then it would be a moon.) There are also some smaller bodies that are kind of round, and no planet is perfectly round, so how round does it have to be? It is even possible for a non-round object to be larger than a round one. And then there is the question of planets outside our solar system; some are large enough that they border on being small, dark stars. And obviously none of these are orbiting the sun; there are probably planets out there which don't orbit stars, having been kicked out by some other object at some point.
Two years ago, the IAU declared a new definition for a planet, which had three criteria: it has to orbit the sun, be round, and also contain most of the mass in its region. Ceres and Pluto do not qualify on the last count, and so they were designated "dwarf planets". Now, they want to create a new category, called "plutoid".
My opinion is, that it does not matter whether we call Pluto a planet or not. It does not change what Pluto actually is. It's simply a matter of convenience, not a real distinction. I'm inclined to not include Pluto, rather than adding a lot of similarly sized objects, but it really doesn't matter. It's just as important that it be studied, no matter what we call it. And fortunately, there is a space probe already on the way there.
2008/08/14
2008/08/13
I miss POPCORN
For most of my life, I have been able to get the exact time of day over the telephone, set by atomic clocks. Here in Northern California, the usual number to call was 767-2676, which is better known by the letters POPCORN. It must have been started by AT&T way back when, and continued for years by Pacific Bell. Then PacBell got absorbed by SBC, which shortly after merged with the rump AT&T, and the new AT&T canceled the service last September, which I found out when Daylight Saving Time ended. As Lily Tomlin said, "We don't care. We don't have to. We're the phone company."
Now, it could be argued that it's not necessary anymore, since many devices are synced to atomic time, including cable boxes and computers. In fact, the very cell phones that we use to call POPCORN display the time updated from the cell network, and many people use their phone instead of a watch. My problem with this is that, the time is usually wrong! That is, I have noticed that it can be as much as a minute off from atomic time. I don't know why; maybe it updates occassionally and then drifts inbetween updates. Now, that is not much, and I can live with that most of the time, but when I am setting the clock on my car dashboard, or wherever, I want it to the second, not a minute off.
Fortunately, I have free long distance in the contiguous US, so I can call WWV at 303-499-7111, which is operated by the National Institute of Standards and Technology (NIST). This gives the time in both Mountain Time and UTC, which is good enough. I don't call it very often; mostly when the time changes twice a year, or when the dashboard clock gets reset at the shop. But it's nice to know it's there.
Well, my cab got worked on the other day, and I needed to reset the clock. But when I called WWV, I got no answer. I called back several times and finally got an answer, but when I called again it just rang again. I am not sure, but I suspect that they have been getting a lot more calls since the end of POPCORN and similar numbers across the country, and are exceding their capacity. Or it could be just a coincidence.
Now, it could be argued that it's not necessary anymore, since many devices are synced to atomic time, including cable boxes and computers. In fact, the very cell phones that we use to call POPCORN display the time updated from the cell network, and many people use their phone instead of a watch. My problem with this is that, the time is usually wrong! That is, I have noticed that it can be as much as a minute off from atomic time. I don't know why; maybe it updates occassionally and then drifts inbetween updates. Now, that is not much, and I can live with that most of the time, but when I am setting the clock on my car dashboard, or wherever, I want it to the second, not a minute off.
Fortunately, I have free long distance in the contiguous US, so I can call WWV at 303-499-7111, which is operated by the National Institute of Standards and Technology (NIST). This gives the time in both Mountain Time and UTC, which is good enough. I don't call it very often; mostly when the time changes twice a year, or when the dashboard clock gets reset at the shop. But it's nice to know it's there.
Well, my cab got worked on the other day, and I needed to reset the clock. But when I called WWV, I got no answer. I called back several times and finally got an answer, but when I called again it just rang again. I am not sure, but I suspect that they have been getting a lot more calls since the end of POPCORN and similar numbers across the country, and are exceding their capacity. Or it could be just a coincidence.
Georgia on my mind
I recently drove some Georgians in my taxi, and they explained about how depressed they were about what is happening in their home. I've been watching the depressing news over the past few days about the conflict in the country of Georgia, on American, British and Russian media, which give different versions. It apparently started when Georgian forces attempted to take over the breakaway region of South Ossetia, which has been supported by Russia. The Russians retaliated. Both sides are blaming the other; Russia is accusing Georgia of "genocide", while Georgia is accusing Russia of "ethnic cleansing" and attempting "regime change". I think that both share blame. Fortunately, there now appears to be a ceasefire; I hope it holds.
The current conflict raises a difficult question: when do regions have the right to secede from their parent country? It is ironic that Russia supports two breakaway regions in Georgia, while brutally suppressing such regions within their own borders, most notably Chechnya. In defending their actions in Chechnya, Russia pointed out that the US used force to prevent the secession of several states, including another Georgia, during the US Civil War. While those states failed then, some of those same states, along with those on the other side, successfully seceded from the British Empire some fourscore and several years earlier. There are many other secessionist movements around the world. The country of Georgia, itself, seceded from the Soviet Union in 1991, and had previously seceded, in 1918, from Bolshevik Russia, before being reconquered in 1921. The usual resolution of these issues is by force.
I believe in the concept of self-determination. People should be free to democratically choose to be part of whichever government they want. If the parent country wants to keep a region (and they usually d0) then it should use persuasion, other than the threat of force, to make it worthwhile to stay together. This would encourage the parent government to settle outstanding grievances. If that fails, then they should go their separate ways, peacefully.
I mentioned the US Civil War. Would I apply the same principle there? Sure. I would oppose using force to prevent states from seceding from the Union, if that was the will of the people in those states, even though I personally am in favor of maintaining the integrity of the Union. However, there is one difference with the states of the Confederacy: nobody asked the slaves. A large part of the populations of those states, a majority in some, even, were deprived of their rights, and not allowed to participate in the democratic process, just as under apartheid, only worse. However, although democracy was instituted after the war, its practice was brief and not enforced by the national government again until a century later.
One disturbing aspect of secessionist movements is that they tend to be driven by ethnicity. People often want to associate with those with whom they share linguistic, religious and racial/tribal affiliations. Unfortunately, most places are not ethnically homogeneous; different groups live to different extents intermixed with each other, so that if an ethnic enclave secedes, it has smaller ethnic enclaves within it. This is what has repeatedly led to ethnic cleansing and other evils. However, in a society of equal rights and secular rule of law, it does not matter so much who your neighbors are. What difference does it make whether I live under this government or that one, if they are the same, and leave me alone? It also helps if there is devolved local authority, rather than strictly centralized control. The more liberal and democratic a country becomes, the weaker secessionist movements seem to be.
The current conflict raises a difficult question: when do regions have the right to secede from their parent country? It is ironic that Russia supports two breakaway regions in Georgia, while brutally suppressing such regions within their own borders, most notably Chechnya. In defending their actions in Chechnya, Russia pointed out that the US used force to prevent the secession of several states, including another Georgia, during the US Civil War. While those states failed then, some of those same states, along with those on the other side, successfully seceded from the British Empire some fourscore and several years earlier. There are many other secessionist movements around the world. The country of Georgia, itself, seceded from the Soviet Union in 1991, and had previously seceded, in 1918, from Bolshevik Russia, before being reconquered in 1921. The usual resolution of these issues is by force.
I believe in the concept of self-determination. People should be free to democratically choose to be part of whichever government they want. If the parent country wants to keep a region (and they usually d0) then it should use persuasion, other than the threat of force, to make it worthwhile to stay together. This would encourage the parent government to settle outstanding grievances. If that fails, then they should go their separate ways, peacefully.
I mentioned the US Civil War. Would I apply the same principle there? Sure. I would oppose using force to prevent states from seceding from the Union, if that was the will of the people in those states, even though I personally am in favor of maintaining the integrity of the Union. However, there is one difference with the states of the Confederacy: nobody asked the slaves. A large part of the populations of those states, a majority in some, even, were deprived of their rights, and not allowed to participate in the democratic process, just as under apartheid, only worse. However, although democracy was instituted after the war, its practice was brief and not enforced by the national government again until a century later.
One disturbing aspect of secessionist movements is that they tend to be driven by ethnicity. People often want to associate with those with whom they share linguistic, religious and racial/tribal affiliations. Unfortunately, most places are not ethnically homogeneous; different groups live to different extents intermixed with each other, so that if an ethnic enclave secedes, it has smaller ethnic enclaves within it. This is what has repeatedly led to ethnic cleansing and other evils. However, in a society of equal rights and secular rule of law, it does not matter so much who your neighbors are. What difference does it make whether I live under this government or that one, if they are the same, and leave me alone? It also helps if there is devolved local authority, rather than strictly centralized control. The more liberal and democratic a country becomes, the weaker secessionist movements seem to be.
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