My Science School

You’ll find it 1,000 miles (1,600 km) from shore in the vast expanse of the Pacific Ocean midway between Hawaii and California. Bleach bottles and old garbage bins bob amid fishing nets tangled with rotting sea creatures. Scientists call this swirling mass of trash the Eastern Pacific Garbage Patch. Twice the size of Texas by some estimates, it’s the world’s largest dump.

The seafloor beneath the Great Pacific Garbage Patch may also be an underwater trash heap. Oceanographers and ecologists recently discovered that about 70% of marine debris actually sinks to the bottom of the ocean.

 

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Soda bottles tumble into the surf. Garbage cans fall off ships. Grocery bags blow out to sea. About 260 million tons (235.9 mt) of plastic are produced each year worldwide, and as much as 10 percent of it ends up in the ocean. Unlike food and other organic garbage, plastic doesn’t dissolve; it just breaks into smaller and smaller pieces that can stick around for centuries. Twine, toothbrushes, discarded toys, to-go bags, and less identifiable pieces of plastic drift around and around in an enormous ocean vortex created by currents, sort of like a slowly flushing toilet that never drains.

 

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Dolphins, seals, whales, sea lions, manatees – these aquatic creatures live in world of water, but their drinking habits are more in line with those of camels and other animals of the desert. Salty seawater is as toxic to marine mammals as it is to us. When they need a drink, marine mammals grab a bite to eat, sucking the moisture from fish, squid, and other aquatic entrees. Seabirds such as terns and albatrosses, meanwhile, have special glands near their eyes that absorb the salt from seawater and flush it out their beaks.

 

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Marine (our ocean) fish are stantly drinking to keep their bodies hydrated, but not all that water goes to their bellies. Some of the seawater passes over special salt-extracting cells in their gills; the rest is swallowed down. A saltwater fish’s gills and kidneys work overtime to process all the salt and flush it back into the ocean. Freshwater fish and sharks, meanwhile, don’t need to drink water. Water passing over their gills combined with the chemical makeup of the fluids in their bodies keep them hydrated.

 

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Ah, you must be thinking of the ‘’Roswell incident,’’ in which an unidentified craft crashed near the small town of Roswell, New Mexico, U.S.A., in 1947.  Conspiracy theorists claim the craft was a flying saucer and that the U.S. military whisked away the wreckage along with the bodies of its alien pilots. The U.S. government released a report on Roswell in the mid-1990s claiming the debris was actually a crashed balloon in its top-secret ‘’Project Mogul,’’ which used high-altitude sensors to monitor for enemy nuclear-missile tests. ‘’Likely story,’’ claim the conspiracy theorists.

 

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The frozen surface of Jupiter’s moon Europa hides a liquid ocean that might contain alien creatures. Enceladus, one of Saturn’s many moons, has a sea the size of Lake Superior under its icy surface. Enceladus has some very surprising features that make it very interesting to astrobiologists. It is white and reflects almost 100% of the light that strikes it. It also has geysers on its surface that shoot out jets of water with ammonia and organic compounds. The temperatures near these geysers are likely very high. And Titan, Saturn’s largest moon, has vast lakes of liquid methane. If life existed here, it would be truly alien.

 

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Astronomers peering at Mars in the 17th, 18th, and 19th centuries saw signs of life everywhere. Seas! Continents! Canals that carried water to Martian farms! But modern telescopes, probes, and NASA landers ruined the fun by revealing our planetary neighbor’s dry details: It’s just a lifeless ball of red rock. Early astronomers had confused Mars’s ancient seas and riverbeds for signs of civilization.

 

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By digging: Robotic rovers are sampling Martian soils for signs of ancient life.

By visiting: Probes are being dispatched to spots across the solar system that might harbor life today.

By looking: NASA’s Earth-and space-based telescopes have been scanning the galaxy for Earthlike exoplanets outside our solar system capable of supporting life.

By listening: In 1960, scientists began scanning the universe with special telescopes for radio signals from alien civilizations. The project is called SETI, or the Search for Extraterrestrial Intelligence. It hasn’t picked up any alien broadcasts yet, but we haven’t stopped listening.

 

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When the Viking I orbiter snapped pictures of Mars in 1976, one photo became a hit for its apparent portrayal of a mountainous Martian face resembling an Egyptian pharaoh. Eager to set the record straight on this crowd-pleasing Mars anomaly, NASA used a satellite to re-photograph the region in 1998 and 2001. The high-resolution images revealed a natural geological feature rather than a monument to Martian kind.

As the Viking 1 mission circled the red planet in search of a landing site for its sister ship, Viking 2, it snapped photos of Mars for engineers at NASA to study. On July 25, 1976, it captured the image of a pile of rocks that greatly resembled a human face. When NASA released the photograph almost a week later, they described it as a "huge rock formation in the center which resembled a human head."

 

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Not so fast, Earthling! Outer space is a big place, and one thing scientists have learned from studying life on Earth is that organisms can thrive in all sorts of harsh environments. Meanwhile, astronomers have discovered nearly 4,000 Earthlike planets beyond our solar system and are spotting more every day. Some of these ‘’exo-planets’’ orbit their stars in the ‘’Goldilocks zone,’’ a distance that’s neither too hot nor too cold to support liquid water and possibly alien life. Who knows? Maybe an alien kid somewhere up there is wondering if you exist.

 

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At first, free fall can feel like roaring down a hill in a roller coaster or one of those sudden-drop rides at amusement parks. But these rides are thrilling – and a little scary – because passengers can see the world whiz past them and the ground rush at their feet. Astronauts only see the inside of their spaceships or the distant Earth and stars outside the windows, so they don’t have any visual clues that they’re falling. To them, free fall feels as if gravity has switched off. The feeling can be disorienting – and a little sickening for some. Two-thirds of the passengers about NASA’s “Vomit Comet,’’ a plane that flies in slow dives to re-create weightlessness, toss their cookies during flight.

 

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Maybe a simple experiment in ‘’orbital mechanics’’ will help. Tie a string to a ball or stick and whirl it around your head. Notice how it travels around you in a circle? Imagine that the object is a spaceship and you are the Earth. The string represents the force of gravity. The same forces are at work when a spaceship orbits the Earth (except gravity, unlike your string, is invisible). If an orbiting ship were to speed up, it would ‘’break’’ free of gravity and travel into space. If were to slow down, it would plummet back to the Earth’s surface (which is precisely how spaceships return for a safe landing). Ships and space stations maintain orbit by ‘’falling’’ around the Earth at just the right speed. Because the astronauts are falling at the same speed as the ship around them, they experience the sensation of weightlessness – or free fall. You would experience the same thing if you were in an elevator and the cable snapped suddenly. The elevator would plummet to the ground with you falling inside it at the same speed. You’d float weightlessly inside the elevator until (hopefully) the emergency brakes kicked in and brought your free-falling experience to a slow stop.

 

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Gravity! Remember, a heavenly body’s gravitational attraction depends on its size. The larger and more tightly packed with matter an object, the stronger its gravity. And weight is really just a measurement of the force of gravity on an object’s mass. Earth is larger than Mars, for example, so our home planet has a greater gravitational tug on all Earthlings and Earth things. That’s why everything ‘’weighs’’ more here. On the smaller asteroids in the asteroid belt, you’d barely notice any gravity at all. One giant leap would launch you into space!

 

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Ah, but astronauts do experience gravity! In fact, without gravity, their ships and space stations would slip from orbit on a one-way trip out of the solar system (which, by the way, would also fly apart without gravity). Although Earth’s gravitational field is slightly less powerful hundreds of miles above the planet’s surface, it’s still more than strong enough to pluck passing space rocks or drifting satellites to the surface and hold the moon in orbit.

 

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Someday, maybe. Researchers at NASA’s Johnson Space Center are looking into ways to beat the universal speed limit with a real-life ‘’warp drive.’’ Just like the propulsion system on the Enterprise from Star Trek, this engine would bend the universe around the ship – shrinking space in front of the ship and expanding it behind – to propel the crew to place at faster-than-light speed. Using this drive, a trip to Alpha Centauri would take just a couple of weeks rather than thousands of years. Of course, this real-life warp drive is only on the drawing board for now. The researchers are trying to create a mini-model of how this could work, and they’ve already mocked up a ship, named – you guessed it – the Enterprise.

 

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