Landsat Island
May 28, 2012 10:53 AM   Subscribe

How did we manage to find every island on earth without satellites?

I imagined that when the first satellite images were reviewed there would have be hundreds of small islands (and possible a larger one or two) discovered. But, according to wikipedia, Landsat Island is the only one. And it's tiny, only 1,125 m².

The Oceans are HUGE! So how is it that we found every other island without satellite imagery? I don't image there are any undiscovered islands remaining (previously). So we somehow found all of them just by sailing around, that just seems unbelievable.

What is the explanation for this?
posted by zinon to Science & Nature (21 answers total) 16 users marked this as a favorite
I'd imagine the advent of widespread flight made a few island discoveries.
posted by Sternmeyer at 10:55 AM on May 28, 2012 [1 favorite]

Lots and lots of sailing. I've always been amazed by how people as early as 300CE would have reached, and settled on Hawaii, for instance. A speck in the middle of an enormous ocean..

I figure though, that for the most part, most islands are fairly close to the shorelines of major land masses, and it wouldn't require extensive sailing to discover most of them.
posted by smitt at 10:56 AM on May 28, 2012

We had airplanes that could fly across the ocean long before there were satellites.
posted by brainmouse at 10:58 AM on May 28, 2012 [2 favorites]

Islands aren't difficult to find -- ancient Polynesians found them in canoes over thousands of miles of open ocean.

A person standing in a boat can see a radius of about 30 miles. Go higher, in a mast, and you can see much, much farther. Plus, you just need to see the tops of mountains, not the whole island.

Now, you're also looking for birds, sea life, shallow water and local weather effects that all tell you that land is near. It's not easy, but it's certainly not impossible.
posted by Cool Papa Bell at 10:59 AM on May 28, 2012 [7 favorites]

This left the problem of accounting for the presence of the Polynesians in such isolated and scattered parts of the Pacific. According to Andrew Sharp, the explorer Captain James Cook, already familiar with Charles de Brosse’s accounts of large groups of Pacific islanders who were driven off course in storms and ended up hundreds of miles away with no idea where they were, encountered in the course of one of his own voyages a castaway group of Tahitians who had become lost at sea in a gale and blown 100 miles away to the island of Atiu. Cook wrote that the Atiu incident, "will serve to explain, better than the thousand conjectures of speculative reasoners, how the detached parts of the earth, and, in particular, how the South Seas, may have been peopled"

-Polynesian Navigation
posted by vacapinta at 11:01 AM on May 28, 2012 [3 favorites]

Also, charting the oceans, coasts, and other waterways was an extremely important endeavor for maritime empires and subsequent polities. It got a similar level of investment that highway-building did in the 20th century United States, for example.
posted by XMLicious at 11:09 AM on May 28, 2012 [2 favorites]

By 1800 or so you had thousands of ships travelling all over the globe in search whales every year, or carrying sea otter pelts from the Northwest Coast of North America to China, and the creation of the steam-powered craft would make it easier to go anywhere on the planet, even the Southern Ocean, which was effectively like travelling to another planet - descriptions of the fierce storms in the Roaring Forties and beyond remind me of vast storms on the planet Jupiter or something.

Anyway, there have been a lot of people doing a lot of mapping.
posted by KokuRyu at 11:15 AM on May 28, 2012 [1 favorite]

The Wikipedia page on phantom islands is quite illuminating. Even by the eighteenth century navigation was good enough, and mapping was systematic enough, that most cartographic errors got corrected pretty quickly (though the Aurora Islands are still something of a mystery). And you've only got to look at the visualisations of shipping routes that we were discussing here last month to see that there were a lot of ships moving around the world's oceans.
posted by verstegan at 11:27 AM on May 28, 2012 [1 favorite]

[I'm no sure what's going on but please make sure you are answering the question and quit making weird snarky comments about other posters]
posted by jessamyn at 11:28 AM on May 28, 2012 [1 favorite]

There are a number of techniques by which somebody armed only with a boat, a compass and a means of telling the time can systematically sweep an area of sea to find things in it. One might conduct a parallel track seach which has the advantage of being simple - or a sector search in which one methodically heads out in different directions from a starting point. The size of sea area which can be swept in one go by such manoeuvrings depends on the target size - not very big when looking for a swimmer or a boat but pretty large when looking for an island. I suspect that those methodically searching for fish have been practicing such techniques for a very long time - finding any islands would be a bi-product of this effort.
posted by rongorongo at 11:32 AM on May 28, 2012 [1 favorite]

Thing is, back in the Age of Sail, there was a huge incentive for finding islands, especially if they had a resource that your fleets/ships might use, such as food, fresh water, or natives to trade with for those things. Having read some naval books (both novels and nonfiction), if you weren't a ship of war, and sometimes even if you were, you'd stop pretty much anywhere you could to stock up on food and fresh water, perhaps clean the hull or do some maintenance, and let everyone get off the boat so they weren't quite as ready to murder each other after living in tight quarters for weeks or months on end eating old meat and hardtack.
posted by Ghostride The Whip at 12:01 PM on May 28, 2012

When Roald Amundsen discovered the Northwest Passage in 1903-1906, his expedition had limited maps. Even at that late date, the islands around Baffin Bay and northern Canada were not accurately mapped. In fact, one of Amundsen's main goals was mapping.
posted by Flood at 2:03 PM on May 28, 2012

I can't find a better reference (although it is about how Hawaii was discovered), but I remember reading somewhere that the Polynesians (or some similar Pacific Islanders) could detect land masses far away by looking at interference patterns generated by waves. All I remember is a diagram of a small wooden trellis-like structure that they used to interpret wave patterns. Vague, I know, but it's referenced in passing here:

Also here:
posted by Boobus Tuber at 2:09 PM on May 28, 2012

Disasters like the Scilly Naval Shipwrecks of 1707 (the British Navy lost four ships and over 2,000 sailors without a shot fired) prompted governments to spend large sums of money on both cartography and improvements in navigation. The HMS Beagle, for example, was chartered to do hydrographic surveys of the South American coast with new chronometers. Commercial whaling likely contributed to this.

In the 20th century, Antarctic and Arctic exploration was similar to the "space race" with countries competing to collect data. WWII and the Cold War pumped millions of dollars into oceanographic research due to the escalation of submarine warfare. By that time, sonar allowed for ships to perform broad surveys. It wouldn't surprise me if Landsat Island was identified as a hazard on military charts before officially described as an island.
posted by CBrachyrhynchos at 2:12 PM on May 28, 2012

Reading the references in your Landsat Island Wikipedia article, I don't think your statement is true. From the NASA article:

In addition to Landsat Island, Landsat images have also helped to chart previously unknown lakes, islands and even a reef in the Indian Ocean. In Miles Harvey’s book A Brief History of Cartographic Crime, he contends, “satellite technologies have led to one of the most productive periods in the history of cartography, comparable only to the golden age of mapmaking in the sixteenth and seventeenth centuries.”

So maybe Harvey's book would be a good resource.

What I actually went to read the refs for originally though was to argue that Landsat Island is in some way unusual, and that's why it hadn't been found; and indeed it's a frozen tiny snow covered lump. Plus the first person we know of to land on it got swatted off by a polar bear, so it's not exactly a hospitable isle.
posted by nat at 2:36 PM on May 28, 2012 [1 favorite]

Water vapor tends to collect over islands, so even when the land itself couldn't be seen, clouds could, from quite a long way away as well.
posted by oneirodynia at 4:36 PM on May 28, 2012

Though the article says "as of 2006", there have been many more islands found after that via satellite imagery.

I fear that the Landsat 1 page may suffer from a type of bias that I would guess is common on wikipedia:

Those who take the time to write the articles tend to overstate the importance of their subject matter.

I have no reason to believe that the author did this with malice or intent, but as the Landsat 1 page has no reference for the claim in question, I would venture to guess (and it truly is a guess at this point) that the author suffered some kind of framing bias, bandwagon effect, and/or optimism bias.

Then again, I took the time to write this response, so I may be overstating the importance of biases.
posted by cmchap at 7:00 PM on May 28, 2012 [1 favorite]

Water vapor tends to collect over islands, so even when the land itself couldn't be seen, clouds could, from quite a long way away as well.

Well it's more that landmasses heat up much more that water in sunlight, and the thermal upwelling will form clouds.

Also, observing the behaviour of seabirds can clue you in to the presence of nearby but unseen land.
posted by HiroProtagonist at 8:20 PM on May 28, 2012

I have no reason to believe that the author did this with malice or intent, but as the Landsat 1 page has no reference for the claim in question

It may have been well-intentioned, but it appears to have been a spurious interpretation of sources. I have removed the claim in question and provided a source for the discovery, cited in the thread above.
posted by dhartung at 12:27 AM on May 29, 2012

Not only did we find pretty much all of them, but we found some of them several times.

For centuries, until the development of truly reliable marine chronometers, it was considerably easier to plot your latitude reliably than it was to plot your longitude. Thus there were numerous cases of islands discovered by ships and added to the charts which didn't really exist because the ships were in fact hundreds of miles east or west of where they thought they were and were "discovering" islands or island groups that were already on the charts in different positions.

A lot of these were discovered to be errors precisely because the British Navy in particular put a lot of effort into having the best, most accurate charts of the entire world, and would go looking for islands and would try to confirm the location of reported islands.

(Not all these phantom islands were navigational errors, by the way. Some were deliberate fraud, which indicates there was value to be had in discovering a new island, which suggests there would have been a lot of ships out looking.)
posted by Naberius at 6:26 AM on May 29, 2012

It seems that oceanographic exploration was much more thorough than I had thought possible. But my reasoning wasn't completely wrong; as satellite images have revealed other islands, though they are all quite tiny.

Much as I love wikipedia I need to remember it is only as accurate as it's contributors make it (Thanks dhartung for updating that). And I really need to start reading the reference links.
posted by zinon at 6:55 AM on May 29, 2012

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