Impressions of New Zealand

Posted on February 14, 2011 by Administrator

A few days ago I returned to Australia after spending 4 weeks touring various parts of New Zealand. I am now ready to detail my impressions of New Zealand.

New Zealand is a small country in the South Pacific Ocean, located 1200 miles southeast of Australia. It consists of two main islands, called the North Island and the South Island. Auckland, the largest city, is located on the North Island. Christchurch, the second largest city, is located on the South Island. Wellington, the capital and third largest city, is on the southern tip of the North Island – a good central location for the country as a whole. I visited all 3 of these cities, along with journeys by train, bus, ferry, and car through various rural areas and small towns.

The entire country has around 4.3 million people – not a lot of people. The US state of Colorado is a close match to New Zealand both in terms of total land area and total population. The climate is generally cool and rainy, but the local climate can vary considerably from one place to another. Most parts of the country are either hilly or mountainous, but there are some flat areas, the largest being the Canterbury Plains on the east side of the South Island.

For people outside of Australia and New Zealand, the two countries appear to be closely related siblings – much like the US and Canada are similar to each other. In fact, this impression is largely true – the two countries have a lot in common, including a shared language, a similar colonial history, and very close trade and political ties. For me, therefore, my most interesting discoveries were the details that set New Zealand apart from Australia – the things that make New Zealand unique.

During my 12 weeks in Australia, prior to visiting New Zealand, it seemed to me that the relationship between the two countries was about as close as two countries could get. Residents of New Zealand have to the right to live and work in Australia without obtaining a visa – and vice versa. As a result, lots of New Zealanders do in fact live in Australia. Australia is the leading export market for New Zealand products. New Zealand attended the constitutional conventions that resulted in the combining of 6 distinct British colonies into a new entity called Australia in 1901. However, New Zealand chose not to join the new union.

I gained a new perspective on the relationship between the two countries during my 4 weeks in New Zealand. I saw that New Zealanders (or “kiwis” as they like to call themselves) are almost desperate to distinguish themselves from Australia, to step out from the shadow of their larger neighbor – despite the close and friendly ties. You’ll often hear New Zealanders make subtle digs at Australia, while I seldom if ever heard Australians making digs at New Zealand. This reminds me a lot of the relationship between Canada and the US, and the efforts that Canadians make to distinguish themselves from the US.

For me, there were 6 differences between New Zealand and Australia that most impressed me:

1. Differences in the pre-European inhabitants of the two countries

2. Differences in the native plants and animals

3. Differences in the geology and geologic history

4. Differences in the economies, particularly the export products

5. Differences in the landscapes

6. Differences in government land ownership

There were two other attributes that particularly caught my attention:

7. Details regarding New Zealand’s largest cities

8. The large number of immigrants living in both New Zealand and Australia

So here are my thoughts on the above 8 topics:

1. Pre-European Inhabitants

Despite the relatively close proximity of Australia and New Zealand, the two countries are extraordinarily different in terms of their pre-European inhabitants. Australia has been inhabited for tens of thousands of years by aboriginal people who were part of a long-ago human migration from Africa, eastward along the south coast of Asia, and on to New Guinea and Australia via land bridges that existed during the ice ages. The people were primarily hunter-gatherers with a relatively simple material culture.

New Zealand has only been inhabited by humans for around 800 years. The pre-European inhabitants, known as Maori, are Polynesians who migrated long distances by boat from other Pacific Islands located far to the northeast of New Zealand. They had an agricultural society, and brought with them their familiar crops and domestic animals – although not all of the imported plants survived in the colder climate of New Zealand. As an agricultural society, the Maoris were able to support a greater population density than the Australian aborigines. This in turn led to a more developed material culture, along with a more hierarchical society. When the Europeans finally arrived, the Maoris were well-practiced in warfare and could offer a stronger resistance to the intrusion of the whites than the Australian aboriginals could.

Because the aboriginals and the Maori came from completely different parts of the world, they look quite difference and speak entirely unrelated languages. They have little in common, other than that they both arrived before the Europeans did – and that they had both became intimately familiar with the landscape and with the native plants and animals of their lands.

Today, Australian aborigines comprise only 2.6% of the Australian population, while Maoris constitute 15% of the New Zealand population. Furthermore, another 7% of the New Zealand population is composed of Pacific Islanders, whose ancestors migrated to New Zealand in the past century from other Pacific islands. The Pacific Islanders share a similar culture and language to the Maori. The upshot is that Maori and Pacific culture is a powerful force both politically and in forming the national identity of the New Zealand people. The Maori language is an official language of New Zealand, along with English, and most official signage is printed in both languages. You can tune to Maori-language broadcasts on television, including newscasters presenting the news in Maori. Maori themes and topics are ubiquitous in tourist gift shops and literature – far more than aboriginal themes and topics appear in gift shops in Australia.

Of course, Maoris and Pacific Islanders are not distributed evenly throughout New Zealand. I spent my first week in Auckland – where many of the Pacific Islanders live – and the second week in the central highlands of the North Island – where some of the towns have very large Maori populations. But in the South Island I encountered much less Maori influence. On the other hand, everywhere I went, the names of nearly every native plant and animal – especially trees and birds – were of Maori origin. In contrast, in Australia relatively few of the native plants and animals are commonly known by their aboriginal names.

Although the Maoris have not always been treated well by the “pakehas” (New Zealanders of European descent), the Maoris have usually gotten a much better deal than the aborigines of Australia. In particular, the Maoris received the right to vote in 1902, while the aborigines of Australia did not receive the right to vote until 1962 – about the same time as the Civil Rights movement in the US.

2. Native Plants and Animals

When we think of the native wildlife of Australia, most of us first think of kangaroos and koalas. When we think of New Zealand, we think of kiwi birds. But other than the presence of kiwi birds, I had expected the native plants and animals of New Zealand to have a lot in common with the native flora and fauna of Australia. I was quite surprised to find that this is not the case at all.

First of all, Australia is widely known for its wide range of marsupials – not just kangaroos and koalas, but also wallabies, possums, bandicoots, wombats, and so on. I had expected to see other unique marsupials in New Zealand. However, New Zealand has no native mammals at all, other than a few species of bats. None! As a result, birds, insects, and reptiles had evolved to fill the ecological niches that in most other places are filled by mammals. Many of these native animals are now rare or extinct, but it is still fascinating to ponder the many species of flightless birds that once lived in New Zealand, or to view the giant wetas – large insects related to crickets.

As for trees, the forests of Australia are best known for the 600 different species of eucalyptus. I had expected that the native forests of New Zealand would also contain many species of eucalyptus. Again, my expectations were completely wrong. There are no native eucalyptus species in New Zealand. Instead, the native forests are populated by trees that seemed quite different from most of the trees that I had learned or seen in Australia.

Finally, I had thought that I would see many interesting species of native wildflowers in New Zealand, just as I had done in Australia. In fact, I saw hardly any native wildflowers at all. Part of the issue is that I did not visit New Zealand at the correct time of year to see the wildflowers. But it also appears that New Zealand, unlike Australia, does not have such a wealth of wildflowers. In parts of the South Island, there is a great deal of publicity about the colorful wild lupines that bloom in the spring – but these are escaped garden flowers that are not native to New Zealand.

On the other hand, New Zealand has an amazing variety in its species of ferns. These range from very small ferns to giants that take the form of trees. Ferns dominant the understory of most forests, especially the tree ferns. The large number of species translates into a wide range of leaf forms. Second only to kiwi birds, ferns are considered emblematic of New Zealand, and consequently fern images are ubiquitous in New Zealand as logos and other graphic representations.

Speaking of kiwi birds, I was surprised to learn that there are 5 species of kiwis – not just one – and that four of the species are quite rare and extremely limited in their geographic ranges. The four rare species are native to the South Island, and are found only in small pockets on the relatively undisturbed west coast. The one species that is relatively common – the North Island Brown Kiwi – is found only on the North Island, and even this species is rarely seen.

3. Geology and Geologic History

Prior to my visit to New Zealand, I knew that the country sits along the Pacific Ring of Fire – a zone of earthquakes and volcanoes that surrounds the Pacific Ocean – while Australia does not. I also knew that the South Island is famous for its mountains. But otherwise I had not thought much about the geology of New Zealand, and I assumed by default that the geology must be somewhat similar to that of Australia. Therefore I was surprised to learn that the geology and geologic history of New Zealand are quite different from that of Australia – although there are some common elements, due to the fact that New Zealand was once attached to Australia.

Australia is an ancient continent – much of the land was created a very long time ago. As a result, there are extensive areas of Precambrian rock in Australia, while no Precambrian rock can be found in New Zealand at all. Many of the places that I have visited in eastern Australia are dominated by flat layers of sandstone deposits, including the Blue Mountains just to the west of Sydney. In contrast, much of the land in New Zealand’s North Island is of volcanic origin. The South Island includes large areas of marine deposts that have been metamorphosed and uplifted.

Because New Zealand sits along the Pacific Ring of Fire, I was not at all surprised that a plate boundary (between two tectonic plates) passes nearby. But I was quite surprised to learn that the plate boundary actually passes through the South Island, and that as a result, most of the South Island sits on a different plate than the does the North Island. The North Island sits on the Australian plate – the same plate that Australia sits on. Most of the South Island sits on the Pacific Plate – the same plate that Los Angeles sits on. (Note: Most of North America sits on the North American plate. But the coast of California southward from San Francisco – the land that is west of the San Andreas fault – sits on the Pacific plate.)

Even more surprising is that the boundary between the Pacific and Australian plates is moving in opposite directions in different parts of the boundary. Parallel to the east coast of the North Island, the Pacific plate dives westward beneath the Australian plate. The subducting Pacific plate melts as it slides beneath the North Island, resulting in ongoing volcanic activity in various parts of the North Island. South of the South Island, the Australian plate is sliding eastward beneath the Pacific plate. The crossover zone, where neither plate can slide beneath the other, is the mountainous region down the west side of the South Island – the New Zealand Alps. In this zone the two plates crush together in a transverse fault, uplifting the mountains.

The upshot is that the North Island is full of volcanic cones and geothermal activity, while the South Island has the highest mountains and the most serious earthquakes. I was quite surprised to learn that most of the hills in the city of Auckland are volcanic cinder cones. It was also interesting to see that while the beaches in Australia are full of white sand – quartz sand eroded from the sandstone and other rocks – the beaches in New Zealand are often black or gray, and often pebbly.

4. Economies and Exports

Because of the tight ties and similar history between Australia and New Zealand, I expected the two countries to have similar economies. But in many respects the two economies are quite different. Australia’s export economy depends to a large extent on mining, and the boom times in Australia right now are primarily due to the high demand in China for Australia’s mineral exports – such as iron ore and coal. Australia also has a noteworthy manufacturing sector. In contrast, New Zealand’s economy is primarily agricultural. Much of New Zealand’s land is dedicated to grazing. The resulting products include wool and dairy products, which are exported in large quantities. New Zealand also exports a lot of timber, the vast majority of which is Monterrey pine (Pinus radiata), a tree native to the west coast of California. New Zealand also exports various horticultural products, such as kiwi fruit and other fruits and vegetables. Fishing is also an important export industry. Supplementing these exports, tourism is also an important source of income for the country.

The upshot is that the economies of the two countries are quite different. Yet both countries are prosperous, with a high standard of living. The two economies are somewhat complementary, and as a result the two countries engage in a lot of trade with each other.

5. Differences in the Landscapes

Although much of Australia is desert or semi-desert, the lands near the East coast, where most of the people live, receive adequate amounts of rain all year – or in some cases (as in the recent Queensland floods) too much rain. Flat-topped mountains and plateaus, composed of flat layers of sandstone, rise up as you head inland from the coast. Outside of the population centers, most of the mountains and hills are covered by eucalyptus forests. Sheltered valleys often contain fern trees and other “rain forest” vegetation. (Australians refer to all of the moist forests as “rain forests”, regardless of the actual amount of rainfall.) Westward, beyond the eastern mountain ranges, the land becomes increasingly arid, first turning to grasslands, and finally to deserts. The grasslands of the eastern interior have largely been replaced by irrigated agriculture, similar to the Central Plains of the US.

New Zealand has a very different set of landscapes. Most of New Zealand is either mountainous or hilly – although the Canterbury Plain on the South Island is an important exception. The mountains of New Zealand tend to be steep and rugged, usually lacking the flat tops so common in Australia. The mountains in the South Island are also taller than the mountains of Australia. In its original, natural state, prior to the arrival of humans, 85% of New Zealand was covered by native forests. These forests were dense and quite green, in contrast to the more open and dryer eucalyptus forests of Australia. The remaining 15% of New Zealand consisted primarily of lands that were too high and cold for forest, but it also included places where the soil was too soggy to support forest.

When the Maoris arrived around 1300 AD, they began to cut and burn large areas of forest – to clear agricultural lands, to encourage the growth of bracken fern (an important food source), and to make use of the lumber. By the time Europeans arrived in the early 1800s, the native forest had shrunk from 85% to 55% of the land. The Europeans very quickly destroyed another 30 percentage points, reducing the native forest to just 25% of the land. Much of that 25% is located far from the population and agricultural centers. In the parts of the North Island that I passed through by train or bus, it seemed that far less than 25% of the land was in native forest. In the parts of the South Island that I passed through by train or automobile, native forest had been completely eliminated from at least 99% of the land. To my eyes, much of New Zealand looked like one huge ecological disaster. Instead of native forests, I saw miles and miles of land kept artificially in pasture by the grazing of sheep and cows. In those places where I did see forest, it was almost always in the form of non-native lumber plantations (mostly Monterrey pine) being grown for quick harvest and export.

However, I know that my sample does represent all of New Zealand, despite my traveling 2/3 of the length of the North Island, and half the length of the South Island. For one thing, except for a short stretch in the northeastern part of the South Island, I saw almost no lands dedicated to horticulture, and yet I know that New Zealand grows fruits and vegetables. And the very rainy and rugged West coast of the South Island is likely to be quite different from most of the lands that I saw.

Near the town of Rotorua in the North Island, there is a much-beloved forest that the local people call “the Redwood Forest”. The entire forest consists of non-native trees. The most spectacular section – and the part that is most visited – is a section of several acres planted entirely in California Redwoods. Many people recommended that I visit the Redwood Forest while I was in Rotorua – which of course I did. And indeed it was a very beautiful forest. But I would have liked to have seen a native forest that was equally loved.

The most spectacular landscapes I saw in New Zealand were on the South Island, as we drove inland from Christchurch to see the Southern Alps and the glacial lakes extending south and east from the Alps. We spent two days and nights in the region of Lake Tekapo, Lake Pukaki, and Mt. Cook – the highest mountain in New Zealand. During those days the western slopes of the Alps were covered by dense clouds and heavy rain. The eastern part of the island was mostly sunny and clear. As we approached Mt. Cook from the east, we transitioned in the last few miles from sunshine to light rain and clouds, and finally heavy rain. Mt. Cook was completely hidden by the clouds. Although the Hooker Valley, where we had planned to hike, was getting drenched with rain, the Tasman Valley a few miles away was receiving only light sprinkles. So we did our hiking in the Tasman Valley instead. (Both valleys contain glaciers, so we still got to see a glacier.) On the way back east, the strong winds from the west were blowing raindrops horizontally into areas where the sun was shining brightly. The result was a huge, non-stop rainbow that followed us for miles and miles as we drove.

6. Government Land Ownership

I definitely got the impression that the government in New Zealand is more hands-off than the government in Australia. There used to be several national forests in New Zealand, but these forests were sold off to private companies. There are no agricultural subsidies in New Zealand, but the agricultural sector seems to be doing fine without them. There are only a few national parks in the country, although some of these few are quite spectacular. I was surprised, for example, that despite the many examples of amazing geothermal activity in the North Island – and something found only in 3 countries in the world (the US, New Zealand, and Iceland) – I could not find a national park equivalent to Yellowstone in the US. Most of the best examples of geothermal activity (geysers, etc.) are in private parks. It is far too pricey to visit more than about two of these private parks, so you have to decide which one or two to visit, out of the many that seek your business. I should hasten to point out that some of these private parks are in Maori hands, and there are cultural, historical, and political reasons for leaving them that way. Still, I was quite surprised that there is no geothermal national park.

In contrast, I am amazed and delighted at the many beautiful national parks that are within a relatively short drive of Sydney, Australia. Not only are these parks quite beautiful, but they make it fairly easy to see diverse examples of native forest.

7. New Zealand’s Largest Cities

I spent time in each of New Zealand’s three largest cities – Auckland, Christchurch, and Wellington. None of the cities is very large by US or Australian standards. I like the resulting “small city” feel – fairly quiet, relatively easy to get around, and not very far to any destination in the city.

Auckland, the largest city in New Zealand, occupies a narrow isthmus on the North Island, and as a result the city spans across the island from the East coast to the West coast – a distance of about 10 miles. The downtown overlooks a harbor on the East coast, and includes the Sky Tower – the tallest building in the southern hemisphere. There are lots of students in the city, many of them visiting from Asia. Auckland also has more Pacific Islanders in its population than any other city in the world. The city is quite hilly, and most of the hills originated as volcanic cinder cones.

Christchurch, the second largest city, sits on a flat plain on the East coast of the South Island, but only a short drive to the towering Southern Alps. The city is often described as “the most English of New Zealand’s cities”, and the description fits. The placid Avon River – really just a large stream – winds through the town, and “punt boats” glide up and down the river through the botanical garden. These boats, popular with tourists, are driven by human power – the operator uses a pole to push against the river bottom. At present, the city sidewalks are an obstacle course because of the recent earthquakes. Fences block off the sidewalks in front of all of the damaged buildings, to prevent falling bricks from landing on anyone’s head. Still it is a charming town to visit.

Wellington, the nation’s capital and third largest city, sits on the southern tip of the North Island. The downtown area occupies a tiny strip of land between the harbor and an area of tall, steeply rising hills. It is a dramatic and beautiful setting for a city, and it is this city that most captured my interest. The hills behind the city center remind me of the Oakland and Berkeley hills – and in fact many things about the city reminded me of San Francisco. This impression was reinforced by all the Monterey Cypress trees growing on the hillsides, along with the Monterey Pines. I stayed in Wellington for a full week and went on very long walks almost every day, exploring in many different directions from the downtown.

8. Immigrants in New Zealand and Australia

In both Australia and New Zealand, nearly a quarter of the population is foreign born – an amazingly high percentage. This is double the percentage in the US, where only 1/8 of the population is foreign born. The largest source of immigrants for both countries is Great Britain, and another major source is each other – New Zealanders in Australia and Australians in New Zealand. However, it the Asian immigrants, particularly the Chinese, that are the most obvious, especially in the central business districts of any large city. Already there is a generation of young people growing up with Asian faces and Australian or New Zealand accents.

Both Australia and New Zealand have a low population density. Australia is nearly the same size as the continental US, and yet has only 1/10 as many people. The policy in both countries is that economic growth will require population growth, and therefore the immigration of young people with important skills should be encouraged. In Australia, the state of Western Australia is especially eager to grow its population through immigration. That said, neither country wants to throw its borders wide open – they want to be somewhat selective as to who gets in. And among the general population there are a few ripples of anti-immigrant sentiment, and as a result the governments of both countries have to take a balanced approach to immigration.

Concluding Details

My visit to New Zealand left me with a few additional impressions:

1) Black appears to be national color in New Zealand – despite the predominantly blue national flag (which, by the way, is nearly identical to the national flag of Australia). Most of the athletic wear I saw in New Zealand was black – black T-shirts, black running shorts, black socks, black tank tops, etc. As I walked around Wellington on a warm day, nearly all of the “kiwis” appeared to wearing black summer wear of one sort or another. In Melbourne, Australia, I also saw a lot of black clothing, but that was business wear and winter coats. In the US, most summer wear tends to be either white or brightly colored. So this was quite an interesting phenomenon to me.

2) New Zealanders have a different accent than Australians – although I would be hard pressed to identify the precise differences. The New Zealand accent seems gentler to me, and I liked hearing it. I was surprised at how often I encountered specific references to the New Zealand accent – including two shows on television musing on questions of national identity.

3) Many, many places in New Zealand are exceedingly proud that one scene or another in the Lord of the Rings trilogy was filmed at some nearby location. I kept encountering references to the films in tourist literature, on television, and even on signs in city parks. New Zealanders are well aware that most foreigners know nothing whatsoever about their country – except that the Lord of the Rings was filmed there. If this is all that many foreigners know about New Zealand, then you’ve got to milk it for all it’s worth!

Posted in Diary, Geography, Visiting Places | Leave a comment

Thinking Big: What Exactly Is a Continent?

Posted on December 16, 2010 by Administrator

[This is Part 3 of a 3-part essay. Part 1 was entitled "Making Sense of the Senses". Part 2 was entitled "The Day Pluto Got Demoted". In each of the 3 parts, we look at a simple classification system that plays a key part in our culture and our educational system.]

Question: Name all the continents in the world, and point out each one on a globe.

As with the previous two questions – dealing with planets and human senses – this question assumes the existence of a specific class, in this case “continents”. Furthermore, the question assumes that the class contains only a small number of items, and that we can therefore memorize the entire list.

In light of our previous two examples, perhaps by now you are detecting a certain weakness in this kind of learning. On the one hand, simple classification models are essential to promote additional learning. Each model that we learn provides a framework upon which we can hang additional information. And it certainly can be helpful to memorize the entire list for small classes such as planets, human senses, and continents. But each class is (or should be) based on a set of clear criteria for distinguishing what items are in the class and what items are not in the class. If we simply memorize the list of items in a class, we run the risk that we won’t really understand the criteria upon which the class is based.

When I was a kid in elementary school, there was usually only one “right” answer to this question – what are the continents of the world? The expected answer was (usually) that there are 7 continents – North America, South America, Europe, Asia, Africa, Australia, and Antarctica. However, as an adult, when I met people who were educated in other parts of the world, I sometimes found that they were taught a different model, with a slightly different list of continents. In fact, I have encountered several variations on the model, and therefore several different lists of continents. How could this be? Is there a genuine “right” answer? What are the criteria for determining the right answer?

Even as a school kid, I could see that there were flaws in the model. On our tests we were expected to be able to provide a definition for the term “continent”, but the definition (which seemed to be different in each year’s textbook) never quite matched up with the list of continents. The most logical definition I encountered as a kid was “a large, contiguous landmass surrounded by water”. By this definition, Australia and Antarctica certainly qualified. But this definition had two big problems:

1) Five of the seven continents (North America, South America, Europe, Asia, and Africa) are not completely surrounded by water, but are in contact with other continents. Therefore I saw these not as five continents, but as two – the Americas, and Eurasia-Africa.

2) The word “large” is too vague to be useful. What is the threshold that distinguishes a “large landmass” from one that is not large? It seemed to me as a kid that Greenland was quite large, and therefore ought to be considered a continent.

Also, it seemed to me as a kid that the definition for “continent” and the definition for “island” were essentially identical, except for the size criterion. Therefore, it would make sense to create a single clear criterion that separated “large” from “not large”, and to use this one criterion to distinguish between continents and islands. Consequently, it would drive me up the wall to hear statements like “Australia is the world’s smallest continent and also the world’s largest island.” Why is Australia considered to be an island, but Antarctica is not? What is the criterion that distinguishes a large island from a landmass that is too large to be an island? I never found a teacher or a book that could answer these questions to my satisfaction. As far as I was concerned, if Australia is a continent, then it cannot be an island – no matter what answer was expected on the test at school. Why should these two categories (continents and islands) overlap – with a single item in common between the two classes – when it would be so much cleaner to use a single criterion to separate the two classes?

Of course, the above rationale is based on the assumption that the terms “continent” and “island” share a single definition, distinguished only by the criterion of size. But another definition for continent, slightly different than the previous one, is this:

continent – a very large, contiguous landmass surrounded or nearly surrounded by seawater

There are 3 subtle differences between this definition and the previous one:

1) “large” has been replaced by “very large”

2) “water” has been replaced by “seawater”

3) “surrounded” has been qualified as “surrounded or nearly surrounded”

The third change is the most profound. Even though the phrase “nearly surrounded” is not well defined, it seems clear that North America, South America, and Africa can all qualify as distinct continents under this definition. In each case, the only connection to another continent is via a narrow neck of land. However, Europe and Asia still cannot be separated under this model. Indeed, more than once (starting in middle school) I had a textbook that used a 6-continent model: North America, South America, Eurasia, Africa, Australia, and Antarctica.

Also note that these 3 changes to the definition of “continent” do not apply to the definition of “island”. An island must be surrounded by water – “nearly surrounded” is not good enough. (A small land mass that is “nearly surrounded” by water would be a peninsula.) Furthermore, the liquid surrounding a continent should be seawater, but for an island any kind of water will do. Therefore an island can be located in a lake or a river. (An island surrounded by seawater can be called a “sea island”.) Also note that an island located in a lake or river will be surrounded by a continent, or by a larger island. This leads to an interesting result. Even though our definition for “continent” includes the phrase “contiguous landmass”, we usually include any river or lake islands as part of the continent, even though they are not contiguous. In fact, we usually include the rivers and lakes as part of the continent too – and therefore the surface of the “continent” includes both land and water. This raises the question of whether we need to replace or enhance the phrase “contiguous landmass”.

From a practical standpoint, we typically go a step farther. If a sea island is separated from a continent by nothing more than a small channel, then we consider the island to be part of the continent. But now another vaguely defined idea has crept into the overall concept. How big can the “small channel” be before the island is no longer part of the continent? One practical way of solving this question is to see if the island is located on the continental shelf of the continent. If so, then the island can be considered to be part of the continent. (But when measuring the area of the continent, the continental shelf is not usually included.)

Our definition of “continent” is now beginning to look like this:

continent – a very large, contiguous landmass surrounded or nearly surrounded by seawater, along with any rivers and lakes located on the landmass, together with any islands located on the landmass or on the continental shelf

With this enhanced definition we still have only 6 continents – Europe and Asia remain combined into “Eurasia” – but at least we have a much clearer idea of what is included within any single continent. Still, the most popular model includes 7 continents, separating Europe and Asia into two continents. Furthermore, there are other models floating around out there. For example, one friend of mine who was educated in South America told me that she was taught in school that “Oceana” is a continent. This supposed continent includes all of the Pacific islands. Is there any way to modify our definition of “continent” to accommodate one or more of these other models?

One approach is to give up on creating a complete definition, and instead admit that the term “continent” refers to a culturally determined set of objects, rather than a set of objects defined by a common set of criteria. Personally I prefer to avoid this route. However, this was indeed the approach taken in Wikipedia, where the following definition is given: “A continent is one of several large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents – they are (from largest in size to smallest): Asia, Africa, North America, South America, Antarctica, Europe.” Although I think that the Wikipedia explanation is very well worded, it essentially says that the word “continent” cannot be defined. In fact, we have already created a definition, containing a clear set of criteria, which generates nearly the exact same set of continents. The only difference is that the traditional list of continents separates Eurasia into Europe and Asia – even though no such separation can be justified based on physical geography alone. Why are we so attached to distinguishing between two “continents” that are so – hmm – attached?

Part of the answer is that the Europe and Asia just seem so far apart. When we conjure up stereotypical pictures in our mind of “Europe”, we think of Western Europe. When we imagine stereotypical pictures of “Asia”, we think of Eastern Asia. There is indeed a large physical distance between these stereotypical locations, and perhaps an even greater cultural distance. Our minds rebel at incorporating so much diversity within the category of a single “continent”. Intuitively, we expect a certain homogeneity within a continent, so that we can assign a set of typical characteristics to it. It’s easy enough to come up with stereotypical concepts for any of the other continents – North America, South America, Africa, Australia, Antarctica – but it’s awfully hard to do this for “Eurasia”. And while our stereotypes are indeed drawn in part from physical geography – for example, Antarctica is icy while Africa is tropical – a very large part of our stereotyping is based on human cultural geography. We don’t distinguish between Europe and Asia based on climate or topography – we feel compelled to distinguish between them based on human and cultural differences.

So while our definitions for “continent” focus exclusively on factors related to physical geography, intuitively we rely to an equal extent – or perhaps an even greater extent – on our concepts of human and cultural geography to distinguish the continents. This phenomenon has several interesting side-effects, including the following two:

1) If you ask someone in the US to point out on a map or a globe where North America ends and South America begins, many people have a very hard time doing so. If you base it strictly on physical geography, it seems obvious that the dividing line ought to occur where the connection between the two continents is narrowest – in Panama. This puts Mexico and all of the Central American countries into North America. But people tend to blend the physical concept of “South America” with the cultural concept of “Latin America”. As a result, people will often want to put the North America / South America dividing line somewhere in the vicinity of Mexico. Of course, the Mexicans have no doubt that they live in North America! (Have you heard of NAFTA – the North American Free Trade Agreement?)

2) In the US, it is popular to designate ethnicity with a hyphenated term, where the second word in the term is “American”. Two of the most popular terms are “African-American” and “Asian-American” – both of which obviously refer to specific continents of origin. But you would never refer to someone of Algerian, Moroccan, or Egyptian heritage as an “African-American”. You would have to say “Arab-American” instead, which is clearly a cultural and regional term. On the other hand, it would be perfectly acceptable to refer to someone with Bahamian heritage as an “African American”. You would probably never use the cultural/regional term “Caribbean-American” for such a person. In other words, we associate certain physical characteristics with the term “African-American” – characteristics associated with people whose ancestors ultimately came from sub-Saharan Africa.

If I say “Asian-American”, most likely you would immediately think of people whose ancestors came from Eastern Asia – Chinese, Japanese, Korean, Vietnamese, etc. You might be somewhat surprised if you learn that I was referring to someone whose parents came from India. You would be even more surprised if you learn that I was referring to someone born in Israel. In fact, you might strenuously object, saying “That person is not an Asian-American!” Again, we associate certain physical characteristics with the term “Asian-American”, and if the person does not have those characteristics, then the term does not seem to fit. In short, our mental images for the terms “African-American” and “Asian-American” are both based in part on the old, discredited model of 3 human races – Caucasoid, Mongoloid, and Negroid – rather than the continent of origin.

But suppose we divided the world into “continents” – actually cultural regions – based entirely on ethnicity, culture, and language instead of physical geography. Further suppose that we are not allowed to divide the world into more than 9 major cultural regions. What would those regions be? Here is one possible list:

1) North America (US & Canada)
2) Latin America
3) Europe
4) Middle East (includes North Africa)
5) Sub-Saharan Africa
6) East Asia
7) South Asia
8) Pacific Islands
9) Anzac (Australia & New Zealand)

Although some of boundaries between these 9 cultural regions are a bit fuzzy, this list of world regions seems quite reasonable. Perhaps the most amazing thing about this list is that is correlates to a fairly high degree with our concepts of the physical continents – and yet it is not intended to reflect the physical continents at all. Each of the 7 standard continents (excluding Antarctica) matches up fairly closely to one of the 9 cultural regions – except for Asia, which is split into “East” and “South” cultural regions. (The two additional regions, not corresponding to standard continents, are the Middle East and the Pacific Islands.) This correlation is primarily due to the fact that the physical continents have always been a very important factor in shaping the boundaries of the various cultural regions of the world.

So back to the original question: Name all the continents in the world, and point out each one on a globe. Although the standard answer is that there are 7 continents – North America, South America, Europe, Asia, Africa, Australia, and Antarctica – this answer is not based on a clearly defined set of criteria. There is a competing model with only 6 continents – North America, South America, Eurasia, Africa, Australia, and Antarctica – that can be defined with a strict set of physical criteria. However, this model is not popular with the general public, because the popular concepts of “continent” blend human geography with physical geography. We can easily devise a model that divides the world into 9 (or fewer) major cultural regions – and this model has a lot in common with our popular concepts related to “continents” – but a model of cultural regions is unlikely to replace our model of continents. So for the foreseeable future, it appears that we will continue to muddle along with our muddled standard model of 7 continents.

That concludes our examination into the third class on our list – continents. We have now looked in detail at one specific type of mental model – a flat classification system containing only one class and no more than 9 items in the class. Our three examples were human senses, planets, and continents. We have seen that for each of these 3 examples, it is possible to construct an alternative model that logically is just as valid (if not more so) than the “standard” model. Yet in each case we teach our kids the standard model as if it were an enduring truth, rather than simply one possible model of many. In fact, I would say that it is beneficial to teach our kids that there is one standard model for each of these classification systems. These models, even if imperfect, are enormously helpful as tools that enable additional learning. But if we want our kid to be creative thinkers – if we want them to be able to “think outside the box” – then we should also teach them that alternative models exist, and that these alternative models, while non-standard, can provide some fascinating food for thought.

You may ask, “Are there any other classification systems of this same type – one class with no more than 9 items in the class – that play an important role in our culture and in our education system?” That’s a great question! In the future, each time that you or your child is asked to learn or make use of a simple classification system, you should ask yourself, “Is there only one class in this system, with no more than 9 items in the class?” If the answer is yes, then you have encountered the same type of classification model that we use for human senses, planets, and continents.

In the next chapter [a future essay], we’ll look at the next type of classification system – where a class is divided into a limited number of subclasses (no more than 9), but there may be many, many items in each class.

Copyright © 2010 by R. Philip Bouchard. All rights reserved.

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The Day Pluto Got Demoted

Posted on December 11, 2010 by Administrator

[This is Part 2 of a 3-part essay that looks at some of the simple classification systems that form a cornerstone of how we think, learn, and teach. Part 1 was entitled "Making Sense of the Senses". Part 3 will follow in a few days.]

Question: How many planets do we have in our solar system, and what are their names?

A strange thing happened in 2006. At the beginning of the year we had 9 planets in our solar system. But at the end of the year we had only 8 planets in our solar system. You might therefore ask, “What cataclysmic event could have caused us to lose a planet from our solar system?” The cataclysmic event was that we made a small adjustment to the definition of the term “planet”, and as a result, Pluto no longer qualified. The solar system did not change – it was only our model of the solar system that changed.

It has been known for centuries that our solar system contains more objects than are contained in our short list of planets. There’s the sun; there are moons; there are comets; there are asteroids. There are many other objects that don’t fit into any of these classes, for which we need additional classes. Furthermore, for some of these classes – such as comets – we know that we have not yet identified every object that falls into the class. In other words, we know that more comets will be discovered in the future. But in the case of planets, we have for thousands of years relied on a countable list of objects. On the other hand, the number of objects in the class has changed several times. Therefore the demotion of Pluto, and the reduction of the class from 9 objects to 8, was simply the most recent change to the class.

The original list of planets contained only 5 objects – Mercury, Venus, Mars, Jupiter, and Saturn. These are the 5 objects that appear in the night sky, which look a lot like stars to the naked eye, but which wander from one constellation to another instead of staying fixed in a particular constellation. So that was the original definition of a planet – a wandering star. As our model of the solar system improved, and we realized that the planets orbit around the sun instead of the earth, we came to realize that our own Earth was a planet too. So now the list had grown to 6 objects. As telescopes became stronger, and the mathematics of planetary motion became more refined, we came to realize that there are additional planets in our solar system, not visible in the night sky to the naked eye. So we eventually added Uranus to the list, then Neptune, and finally Pluto. But with each addition, we made the assumption that the newly discovered object can be reasonably categorized as a planet, rather than some other type of body.

However, Pluto was always something of an odd planet. First, it is smaller than any of the other planets. Second, it has an eccentric orbit that is less circular than the orbits of the other planets, so that sometimes Pluto is closer to the sun than Neptune. (When this happens we have to ask, is Neptune or Pluto the ninth planet?) Finally, the orbit of Pluto is tilted considerably compared to the orbits of the other planets.

None of these differences were very important when we thought that Pluto was unique. But in recent years we have come to realize that there are many Pluto-like objects out beyond Pluto. Most of these objects are smaller than Pluto, but at least one of these objects (named Eris) is bigger than Pluto. So this forced the question – should we consider some of these additional objects to be planets, and if so, then which ones?

Of course, this raises the question as to the precise definition of the word “planet”. From that definition, we need to derive a set of criteria – rules of thumb – that allow us to distinguish between planets and other objects in the solar system which aren’t planets. In our attempt to formulate such a definition, it may be helpful to ask ourselves questions such as these: Why aren’t moons considered to be planets? Why aren’t comets considered to be planets? Why aren’t asteroids considered to be planets? Are there any other objects in the solar system – besides moons, asteroids, and comets – which need to be distinguished from planets?

We exclude moons from the list of planets because moons do not revolve around the sun. Instead, moons orbit around planets. So our definition of a planet should mention that planets revolve around the sun.

Comets revolve around the sun, just as planets do. But their orbits are highly elliptical, rather than having the nearly circular orbits that planets have. Furthermore, the orbits often deviate significantly from the “ecliptic” – the plane that the planetary orbits occupy. In other words, the orbits of the planets constitute a set of concentric rings, all in the same plane (to within a few degrees). But the orbits of the comets are often not within that same plane. Therefore we might want our definition of “planet” to mention having a nearly circular orbit, and the definition should probably mention that the plane of the orbit is nearly the same as the plane of the earth’s orbit.

Asteroids revolve around the sun, just as planets do. Furthermore, most asteroids have nearly circular orbits, and the orbits are usually in the same plane as the earth (within a few degrees). Therefore it seems that asteroids would be good candidates to be classified as planets. However, we exclude asteroids from the list of planets primarily because they are too small to be considered planets. So our definition of a planet should mention a minimum size – although the precise minimum size is a judgment call, and therefore somewhat arbitrary.

If we consider only the inner parts of the solar system – let’s say everything inside the orbit of Neptune – then our four categories (planets, moons, comets, and asteroids) cover most (but not all) of the objects of interest, other than the sun itself. But if we define the solar system as including everything that orbits around the sun, along with anything that orbits around an object that orbits around the sun, then the solar system extends way, way beyond the orbit of Neptune. There are countless objects in the outer solar system, and the vast majority of these objects have never been catalogued. But what are these objects? Are they planets, moons, comets, asteroids, or something else altogether? As we gradually discover these objects, what criteria should we apply in order to assign them to the proper categories?

As we travel beyond the orbit of Neptune, the first region we pass through – still within our solar system – is called the Kuiper Belt. Astronomers have already discovered more than 1000 individual objects within the belt, but far more objects remain to be discovered. One estimate is that the region contains more than 70,000 objects with diameters greater than 100 km (60 miles). The belt occupies a flat ring of space that is more or less in the same plane as the planetary orbits.

Beyond the Kuiper Belt – but still within our solar system – lies the Oort Cloud. The Oort Cloud is thought to be the source of all the long-period comets that enter the inner solar system, such as Hale-Bopp. Unlike the Kuiper Belt, which lies in the same plane as earth’s orbit, the Oort Cloud is a vast sphere that lies in all directions from the sun, extending as far into space as the sun’s gravitation field can have an effect. It is believed that the cloud may contain trillions of objects greater than 1 km in diameter. However, because of the great distance from the earth, no object residing in the Oort Cloud has ever been directly observed. The main evidence for the Oort Cloud is that the orbital paths of the long-period comets indicate that they all originated in this region.

Between the Kuiper Belt and the Oort Cloud lies a region called the Scattered Disc, although some astronomers consider it to be part of the Kuiper Belt. The periodic comets, such as Halley’s, appear to have originated in this region.

As a general rule, the objects in the Kuiper Belt and the Oort Cloud are icy, not rocky or metallic like Earth and the other inner planets (Mercury, Venus, and Mars). Because of their volatile composition, objects from this part of the solar system become comets should they journey into the inner solar system. In other words, when such an object approaches the sun, it develops a visible tail as some of the volatiles vaporize and stream away.

Given the above, how should we classify the various trans-Neptunian objects (TNOs) as they are discovered? Can we use the familiar categories of planets, comets, and asteroids for some of these objects? Do we need additional categories to describe some of these objects?

First let’s consider the term “comet” – which we can define as a small icy body that develops a coma (tail) as it approaches the sun. Such an object cannot have spent much time close to the sun, or else the volatiles would all have evaporated. Therefore such an object must have an extremely elliptical orbit around the sun, so that most of the orbit lies in the very cold regions of the solar system – but part of the orbit takes the object closer to the sun – much closer to the sun than the orbit of Neptune. Given this definition and rationale, most of the TNOs cannot be classified as comets – their orbits never take them close enough to the sun. However, most of the TNOs are potential comets. If their orbits should ever be perturbed due to gravitational interactions with large objects (such as the gas giant planets), then they could become comets. But in the meanwhile they are not comets.

Next let’s consider the term “asteroid”. It used to be that any object orbiting the sun that is not a planet or a comet could be called an asteroid. But the definition of the term has narrowed over time, because such objects in the inner solar system are quite different from such objects in the outer solar system. The main difference is that the objects in the inner solar system are rocky or metallic, like Earth and the other inner planets. Objects in the outer solar system are icy, consisting primarily of materials that turn into liquids or gases when exposed to temperatures like those found on Earth. The orbit of Jupiter is the approximate boundary between the rocky/metallic bodies and the icy bodies. Therefore the term asteroid is now limited to those small objects whose orbits are no farther from the sun than Jupiter. As a result, the trans-Neptunian objects are not asteroids.

So that brings us back to the term “planet”. Can any of the objects beyond the orbit of Neptune (including objects not yet discovered) be classified as planets? Given the earlier discussion, we might define the term “planet” as any object that orbits the sun, provided that the orbit is nearly circular, that the plane of the orbit lies within a few degrees of the ecliptic, and that the diameter of the object is at least half as great as that of Mercury. Of course, to be precise we’ll need to specify just how close to circular the orbit must be. And we’ll have to specify how many degrees from the ecliptic that the orbital plane can deviate. Keep in mind that this is not the only possible definition for the term planet, and that we will consider another possible definition before this discussion is concluded.

So let’s consider the 8 bodies that are unequivocally considered to be planets. All 8 objects orbit the sun, so let’s see how they compare with regards to the other criteria.

Planet Diameter (km) Orbit Eccentricity Orbit Inclination (deg)
Mercury 4,879 0.205 7.0
Venus 12,104 0.007 3.4
Earth 12,756 0.017 0.0
Mars 6,792 0.094 1.9
Jupiter 142,984 0.049 1.3
Saturn 120,536 0.057 2.5
Uranus 51,118 0.046 0.8
Neptune 49,528 0.011 1.8

As you can see from this table, Mercury is the smallest of the 8 principal planets. It also has the most eccentric (non-circular) orbit, and the plane of the orbit deviates the greatest from the plane of earth’s orbit. Now let’s add Pluto to the table:

Planet (?) Diameter (km) Orbit Eccentricity Orbit Inclination (deg)
Mercury 4,879 0.205 7.0
Venus 12,104 0.007 3.4
Earth 12,756 0.017 0.0
Mars 6,792 0.094 1.9
Jupiter 142,984 0.049 1.3
Saturn 120,536 0.057 2.5
Uranus 51,118 0.046 0.8
Neptune 49,528 0.011 1.8
Pluto 2,390 0.244 17.2

As you can see from the second table, Pluto scores worse than Mercury on all 3 measures. It is less than half the diameter of tiny Mercury, its orbit is less circular than that of Mercury, and its orbit is far more tilted than that of Mercury. Therefore, depending upon what we choose as our thresholds, we might say that Pluto fails 3 of the 4 criteria we have set to classify an object as a planet. The only criterion that Pluto meets is that it orbits the sun.

If we consider Mercury as setting the minimum standards that all planets must meet, then do any of the objects in the Kuiper Belt (and beyond) meet these standards? In other words, can we consider any of the 1000+ Kuiper Belt objects discovered so far to be planets? By the Mercury standard, each object must be at least as big as Mercury, have an orbit at least as round as Mercury’s, and have an orbital plane that is no more tilted than that of Mercury. Do any of the thousand known trans-Neptunian objects qualify?

As it turns out, only one of the 1000+ objects (Eris) is known to be larger than Pluto, but even Eris is smaller than Mercury. Therefore every one of the objects fails the size test. We don’t even have to consider the other two criteria. However, it is likely that many of the TNOs would fail one or both of these additional criteria as well. The upshot is that our solar system contains only 8 known planets, and it does not seem highly likely that the Kuiper Belt holds any undiscovered objects large enough to be considered planets.

If we can reject all the known planetary candidates in the Kuiper Belt based on size alone, then do we really need to consider the two orbital characteristics – eccentricity and inclination? Can’t we just define a planet as any object that orbits the sun, provided that it meets a certain minimum size threshold? In fact, in 2006 the International Astronomical Union (IAU) did exactly that. In response to the 2005 discovery of Eris, an object that is larger than Pluto, the IAU revised the definition of the term “planet”. However, rather than choosing an arbitrary size threshold based on units of length (for example, a minimum diameter of 4000 km) to distinguish a planet from an object that is too small to be a planet, the IAU chose another route. They chose a size criterion that would have a distinct physical effect. Thus the IAU’s definition of a planet is the following:

Planet – a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.

Notice that this definition includes 3 criteria. The second criterion is clearly related to size – the object needs to be big enough that its own gravitational forces have shaped it into a sphere. (If the object is spinning quite rapidly, then the sphere may be slightly flattened.) The third criterion is also related to size. If the object is massive enough, then it will not share its orbit with other objects that are also orbiting the sun; it will have cleared its orbit of all other such objects.

By this definition, both Pluto and Eris were excluded from the list of planets. However, the IAU also created a new category, called a “dwarf planet”. A dwarf planet meets the first two criteria, but is not large enough to have cleared its orbit of other objects. Pluto and Eris therefore fall into the category of “dwarf planet”. Several other objects in the solar system also quality as dwarf planets, including Ceres, the largest object in the asteroid belt. Unlike most of the other objects in the asteroid belt, Ceres is large enough to have rounded into a sphere. Two additional trans-Neptunian objects have also been designated as dwarf planets – Makemake and Haumea. There may be hundreds of additional dwarf planets in the outer solar system – either undiscovered, or not yet studied enough to know that they meet the criteria for a dwarf planet.

The 2006 definition from the IAU included a third size category. If an object is too small to have become rounded into an oblate spheroid due to its own gravitational forces, then it is designated a “small solar system body”. This cumbersome term covers asteroids, comets, and all the other small bodies. In fact, a wide range of sometimes overlapping terms have been proposed or used to designate specific subsets of the small solar system bodies. Some of the more interesting terms include “centaur”, “trojan”, and “TNO” (trans-Neptunian object).

So back to the original question: How many planets do we have in our solar system, and what are their names? The standard answer (since August 2006), the one that we now want our kids to learn in school, is that there are 8 planets in the solar system – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. However, when these kids grow up and have kids of their own, will this still be the correct answer? It is possible that new discoveries will have changed the count by then. But equally likely is that the definition of the term “planet” will have been tweaked again, resulting in a larger (or smaller) set of qualifying objects. So once again, just as with the human senses, we should teach our kids the standard model of the day – but we should also make it clear that other models are possible!

So that concludes our examination into the second class on our list – planets. What about the next class on our list – continents?

[Part 3, discussing the concept of "continent", will appear in a few days.]

Copyright © 2010 by R. Philip Bouchard. All rights reserved.

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