Image of ocean junk washed up on Hawaii (general junk dumped or accidentally lost).
The primary ocean junk can be classified as:
"A wide variety of anthropogenic artifacts can become marine debris; plastic bags, balloons, buoys, rope, medical waste, glass bottles and plastic bottles, cigarette lighters, beverage cans, polystyrene, lost fishing line and nets, and various wastes from cruise ships and oil rigs are among the items commonly found to have washed ashore. Six pack rings, in particular, are considered emblematic of the problem." [Wikipedia]
In satellite images, much of the human-made junk can reflect light, including glass, plastics of all sizes and weights, and some metals.
As well, waveform tops reflect light, including the swell and the spray from a wave.
In the Pacific Ocean in particular now, waste continues to arrive on US shores from the Japan Earthquake & Tsunami of 2011: Scientists estimate debris could continue arriving for another decade+.
As well, some oceans (such as the Indian Ocean) have circular currents that keep circulating debris for years, occasionally kicking out pieces that end up on shorelines (eventually).
Satellite image "coloring"
I am not an expert on why black & white is often easier to search than True Color imagery.
But brains expect "real coloring" so it can take time to adjust and distinguish shapes on B&W.
Most Nodders have noticed that waters closest to shores often are more true color than out in the middle of the water where it is darker.
On B&W, shoreline images still look more like what we expect to see-- specifically because we have a shoreline as reference. Even without blue, we can see parts of the slope nearest the shore. It looks "right".
But further offshore, and with B&W images, the ocean surface can look fairly dark with grays, deeper blacks, shadows, and what I call "sparkles" from waves.
From Libya here is an overview of a section with the browser window at about 50% (to see a wider area). By the way, from what I saw of a city nearby, these images were taken during daylight hours, and were made into B&W during processing.
Notice the lighter grays that run usually in "lines". You can also see darker sections between the waves--- and these often appear to have "shapes" even when it is nothing. Here and there, you see a sparkle "dot" or white slash. Many people might think those are objects, such as boats. But if you look at the measurement on the bottom of maps, you will see that the size is very small, too small for a big boat.
Here is the same area at 100%---
Here you can see the waves more clearly, and see that the surface is not flat; each wave has some height.
Objects in the Ocean
For Libya Ghost Ship, we have been asked to tag any ships we see.
I happened to spot one tonight. This was set at 33% browser size, because I wanted to show the full ship which is crossing a "corner" of the satellite image strips (so it is on 4 tiles).
Now, people have asked about what the images would look like if we were doing a search for a missing sailboat or downed airliner. I wanted to show some images so new folks can get an idea of size(s). Look at the ship...it has white 'blocks'--- perhaps those are cargo containers. Now as you look at just one of those white blocks, try to imagine the size of a regular suitcase in comparison-- the suitcase would be very small.... Now, imagine the suitcase has ripped open at the hinges so it is 2 halves, and all the contents are spilled out.
When a catastrophic violent event happens, these items all do not float. Imagine, say half, of the contents immediately gets pulled under the water or falls because it has weight... for example, bottle of shampoo, conditioner, full medicine bottles, and other heavy items. Now the other 50% might float, but every wave jostles it, pulls it underwater, moves it by feet, yards, and miles.... As this happens, let's say half of that 50% finally submerges and becomes part of ocean junk carried by currents under the water.
We're now down to 25% in our imagined scene of what might still be floating. But nothing stays constant in ocean waves and currents. Every hour, more of it drifts, and more of it submerges....
Let's say we are now down to 5 to 10 % of that one suitcase that is still floating. But each piece is constantly being taken up and down on the waves. They do not ride on top in plain view.
Look again at the waves in the images here. Do you think you would spot an un-inflated flat life vest (remember, no colors if they do B&W imaging)? Or a shoe? A shirt? The size we're talking about is incredibly small considering the vast area of water and its wave heights.
Also, when clothing or paper objects go through an explosion or hit water and are then 'swooshed' around in a violently large 'washing machine', they rip and shred into pieces. (Nature tries to reclaim everything, so it breaks things apart. (Even seats from this latest airliner are in pieces.) One reason scientists and marine biologists complain about ocean garbage and debris is that nature cannot quickly break down some metals--- and it could take millions of years to break apart plastics and glass!) But everything else, forces act on immediately.
Our brains are immediately attracted to light and sparkles, especially in a landscape (ocean-scape) nearly devoid of recognizable shapes. But we cannot fully rely on sparkling to judge what we are seeing. We need to also consider size, shape, and other known "features"-- such as a wake following a ship that is moving. Don't worry now if you've tagged sparkles-- we ALL do it; sometimes we cannot make our brains understand that a dot is probably too small. But as you search, try to judge whether other features are / are not present. Use your best judgement and gut instincts!
As you look for ships in Libya, try to imagine how difficult it would be to spot very small objects, and objects that are no longer upright (such as a capsized sailboat... ). Imagine if the objects were torn apart or broke apart later.
As well, consider the requests Tn has received to look for missing sailors or fishermen. From this discussion, you can see that it is really, really hard to spot people in water.
I hope these images helps give perspectives about "size" and what an ocean search would "look like".