I am sure you have all read about the new definition of planet, developed by the "Definition Committee" (!) of the International Astonomical Union (IAU):
1. Must be in orbit around a star, while not being itself a star. 2. Must be massive enough for its own gravity to pull it into a nearly spherical state.
Then, there is the new subcategory of "pluton":
1. Must satisfy the technical definition of planet. 2. Resides in orbit around the sun that takes longer than 200 years to complete (i.e. orbits beyond Neptune). 3. Typically has an orbit that is highly tilted with respect to the classical planets and is far from being perfectly circular.
This of course has sparked an intense debate because it means that Ceres, Charon and UB313 (nicknamed Xena) are all planets now. Apparently after a discouraging first day of deliberations, they were surprised (and pleased) to find a definition that appealed to all of them. Do you think it will stick? Any thoughts?
I feel very strongly about this. Pluto is a tiny, insignificant celestial body, with an irregular orbit and no atmosphere. It zigs in and out of the orbit of Uranus more like a rogue comet than a proper planet.
I know there is a lot of affection for Pluto, for whatever reason. However, this must be balanced with the fact that these new regulations will create at a minumum 3 new planets. There are quite a few other objects which may qualify, as we gather more data.
Ceres was originally a planet when it was discovered in the 19th century, but was demoted when the data showed it was quite small. It was given the status of asteroid, "star like". It happened before, it can happen again.
Pluto is a Kuiper Belt object, a large asteroid, practically a comet. With the new regulations, there are 3, and probably many more. What's next? Halley's Planet? The Oort Cloud planets? Ridiculous. The only logical scientific solution is 8 planets.
A day after this stuff hit the papers there was a political cartoon showing a polluted, war-ravaged wreck of a globe, with the caption, "So THIS is a planet?"
Quote: Then, there is the new subcategory of "pluton" I hear they dropped that, and are casting about for another word, because the geologists protested that they are already using the word 'pluton'.
pluton: A body of igneous rock formed beneath the surface of the earth by consolidation of magma. (AHD)
because the geologists protested that they are already using the word 'pluton'
I don't see why that matters. There are several words that mean different things in different scientific disciplines. The context makes it clear which meaning is meant.
Build a man a fire and he's warm for a day. Set a man on fire and he's warm for the rest of his life.
This morning's paper had an article (NY Times News Service) about the debate. The latest proposal is to make Pluto and similar "Dwarf Planets." Another proposal is to call objects smaller or less sperical, such as comets and asteroids, "smaller solar system bodies."
They're not done yet. This from the Boston Globe website:
quote:
Under pressure from a growing faction of astronomers, the planet definers have been tossing around other options: plutoids, plutonids, plutonoids, plutians, or Tombaugh objects or planets in honor of Clyde Tombaugh, the American who discovered Pluto in 1930.
WM
Posts: 1390 | Location: Near Philadelphia, Pennsylvania, USA
I don't feel any sentimental attachment to a cold, remote ex-planet named for the god of death.
But the headlines have been a little harsh. Yesterday I received a Chicago Tribune news alert titled "Solar System Downsized" (I guess you Brits would say "Solar System Made Redundant.") This a.m.'s Philadelphia Inquirer has Pluto as the top headline: "Earth to Pluto: You're Outta Here"
Wordmatic
Posts: 1390 | Location: Near Philadelphia, Pennsylvania, USA
That's a great headline, Wordmatic. Sometimes they are so clever, aren't they? I loved The Wall Street Journal headline, too, that I posted above, "Venus Envy."
There's nothing wrong with correcting a mistake, Z, but I am still going to miss it.
The Rocketboom vlog (video weblog) has some footage from the IAU vote on deplanetizing Pluto in that defenestrating Middle European city, Prague. 'Tis some seriously nerdly astronomical stuff.
Excuse me, but who conferred upon the IAU the authority to define the word "planet"? "Planet" is a commonly used word, and hence its deginition is a linguistic question.
Why shouldn't that definition be provided, as it is for other words, by common usage? By that standard Pluto is a "planet". That may change, if usage changes (and perhaps the IAU action may cause such a change) but until that change is seen to occur, Pluto remains a "planet".
Quotes: "Experts claim that the definition for planets adopted by the International Astronomical Union (IAU) could also see Neptune downgraded. They say that both planets fail to meet all the criteria set by the IAU. ... critics claim that the IAU vote, which was passed by a majority, should be abandoned as only around 400 of the union's 10,000 members took part in the vote in Prague last week."
Excuse me, but who conferred upon the IAU the authority to define the word "planet"?
It was the IAU that gave it planet status in the first place. There's nothing shameful about being a former planet: the sun and moon used to be planets too, so Pluto is in fine company.
So, the question is, what does "clear its orbit" mean. Pluto is in 3:2 resonance with Neptune, as are a number of other Kuiper Belt Objects, meaning that Neptune can never hit Pluto. Furthermore, this makes Pluto sort of a "satellite" to Neptune.
All this stuff reminds me of St Exupery's "The Little Prince," wherein a Turkish astronomer discovers an asteroid. He presents his findings to the IAU, but is not believed because he's wearing traditional Turkish clothing. The next year he presents the same data while wearing Western clothes and is haled as a brilliant astronomer. I think St Ex knew a thing or two about satire - and this subject!!!
There was a funny piece about "reclassifications" today in the Tribune, based on the reclassification of Pluto. Some of them were too regional for everyone to understand, but here are a few of the others:
Antarctica? - A continent? Come on! It's just a big icy island. And don't even get us started on Australia.
Y? Not a vowel. Ever. That's too confusing.
Tom Cruise? - Now he's a "dwarf star."
Goofy? - Disney should send him down to a minor-league theme park.
Capri pants? - Made wearable again by scissors-enabled demotion to shorts.
Pigeons? They're not birds. They're rats with wings.
Chihuahua? A dog? That's not a dog!
Grand Duchy of Luxembourg? C'mon. "Grand?" It's smaller than Rhode Island -- a simple "duchy" will do.
The 10th Commandment? - Coveting thy neighbor's goods is what fuels our consumer economy.
critics claim that the IAU vote, which was passed by a majority, should be abandoned as only around 400 of the union's 10,000 members took part in the vote in Prague last week
Hmm. That seems to show the importance that astronomers give to this issue. Why should the media treat it so feverishly?
Build a man a fire and he's warm for a day. Set a man on fire and he's warm for the rest of his life.
I'm all for demoting Europe as a continent. There is clear division between all other continents, except for Eurasia, which has a piddling mountain range in the Urals to separate it as a continent.
except for Eurasia, which has a piddling mountain range in the Urals to separate it as a continent
Hmm, I thought the demarcation for Europe was further west than the Urals which are way over by Kazahstan and Siberia in the Middle of the Eurasian continent.
I guess I was mislead by Anatolia being called Asia Minor sometimes.
Most of Turkey is in Asia. The border here is the Mediterranean, the most sensible of all of Europe's borders. Actually, the Urals make some sense, since they were created in the merging of two different landmasses. Except for the little tip on the Europe side of Istanbul(not Constantinople). How does Turkey feel about this? Well that's nobody's business but the Turks.
You need to look at history as well as geography when making these kinds of decisions.
Very few people even notice that the centre of the world, according to the most popular world map projection, is Italy, and never think to query why this should be, so familiar is it. It's Itlay because Mercator was Italian and, to be fair, Italy was one of the centres of scientific advancement when he devised his famous cylindrical projection.
Had it been an Englishman a few years later who came up with the idea then London would have been the centre. Now, of course, it would be somewhere in the USA.
Continents are quite arbitrary divisions and, if land-mass size were to be the determinant, then probably Africa would be the centre of the world. As it is, on the Mercator projection Africa looks to be smaller than North America, instead of maybe double the size.
Richard English
Posts: 8038 | Location: Partridge Green, West Sussex, UK
Richard, I think you are discussing two different issues. Yes, the Mercator projection is inaccurate, and distorts Africa badly. However, this is unrelated to the issue of continents.
However, most continents aren't arbitrary divisions. Africa is clearly separate from Eurasia. Australia and Antarctica are even easier to classify. North and South America are barely connected in Panama, so we make the logical division there. The only division that leaves any doubt is Europe/Asia/India, which is a giant landmass. Europe has logical boundaries on 3 sides, as does Asia, and the issue becomes where, if any, the division comes. Because the continents are joined at the Urals, that is where the line is.
At first every country (virtually) set themselves on the prime meridian. At an 1884 international conference it was decided to make Greenwich the prime meridian, mainly because Great Britain was the greatest sea power at the time. However, there were still some dissenters, and France did not 'fall into line' until 1978. See my site on the subject.
Build a man a fire and he's warm for a day. Set a man on fire and he's warm for the rest of his life.
At an 1884 international conference it was decided to make Greenwich the prime meridian, mainly because Great Britain was the greatest sea power at the time
Plus it was Britain that invented railways and it was railways that invented the concept of universal time. Before the railways locations set their own local times according to the sun's position.
Bristol time was about 20 minutes after London time - which mattered not when it took a day to get there by stage coach - and very few people travelled in any case simply because it was so expensive. A stage coach journey to Bristol would have cost more than the annual wages of the average worker.
But once you could get to Bristol in a couple of hours on the GWR for only a penny a mile, it became important for times to be constant and, of course, the railways had to have a standard time for their timetables (another British invention by the Quaker, Bradshaw)
Richard English
Posts: 8038 | Location: Partridge Green, West Sussex, UK
The phenomenon of 'local' time varying from place to place had been known for many years before the introduction of railways. King Charles II set up Greenwich Observatory in 1675 to try to find a way of fixing longitude by the variation in local time from that of a set point. Harrison's chronometers were the first to be accurate enough to be used in this way, and were designed in the 1730s.
The main importance was for navigation and with different charts showing zero longitude at different places on the globe, there was a real danger of confusion.
Build a man a fire and he's warm for a day. Set a man on fire and he's warm for the rest of his life.
I'm not suggesting that the concept of different local times wasn't known before the railways - I'm saying it didn't matter until the railways.
Few people travelled and few people owned watches. It just wasn't an issue. The railways were the first orghanisation that needed to know accurate timings for vehicle scheduling and that needed standard times for the same reason. Indeed, Russian Railways, to avoid the problems of having timetables that need to cope with 8 times zones, run all their trains to Moscow time - which might help them but probably confuses their passengers!
The use of accurate clocks for navigation is a different matter and here the need was not for time, but for position. Time was a means to an end.
Richard English
Posts: 8038 | Location: Partridge Green, West Sussex, UK
The association was with your point about Britain's sea power. Britain's pioneering transport invention of the railways also had a great deal to do with the idea of standard times and hence the concept of standard time zones. It was more than just Britain's naval superiority that made Grenwich the site of the prime meridian.
Richard English
Posts: 8038 | Location: Partridge Green, West Sussex, UK
Time zones were invented in the US. Great Britain, being small enough to fit in a single time zone, had no need for separate zones.
Before the 'prime meridian' was standardized, the major contenders were the meridians of Greenwich and of Paris. In conference, the French agreed to use the Greenwich meridian in return, as I recall, for British agreement to go metric. Britain, of course, did not follow through on the latter.
Britain's pioneering transport invention of the railways also had a great deal to do with the idea of standard times and hence the concept of standard time zones. It was more than just Britain's naval superiority that made Grenwich the site of the prime meridian.
Sorry, but I don't see the connection between time zones and where to put the zero meridian, either. You have to define a zero meridian somewhere whether you have time zones or not. It happens to go through Greenwich because that's where the observations for the nautical almanac were made, hence position was determined relative to that longitude.This message has been edited. Last edited by: neveu,
As Arnie mentioned above in passing: the accurate measurement of longitude (and the arbitrary but necessary longitudinal starting point, i.e., the prime meridian) is important to both marine navigation and cartography, both of which predate railways. The need, also, for accurate measurement of time lead to another British invention, the H-4 (Harrison's chronometer), which also predates railways.
[Fixed typo.]This message has been edited. Last edited by: zmježd,
But the meridians of longitude define time zones; on a rotating globe they must do. The distance between meridians of longitude is one of time, not distance. Regardless of where you start counting them that must apply.
Cartography existed before longitude (or latitude) existed though, I agree, accurate east/west navigation had to await the arrival of the chronometer.
Richard English
Posts: 8038 | Location: Partridge Green, West Sussex, UK
So that when you say "30 degrees west longitude" people know 30 degrees relative to what. The lines of latitude are defined by the Earth; longitude is defined by man.This message has been edited. Last edited by: neveu,
I think St Ex knew a thing or two about satire - and this subject!!!
