Quarks to Quasars

For every person there are roughly 170 million insects.

(Source: news.discovery.com)

One third of the world’s population has never made a telephone call.

(Source: )

Jimmy Carter was the first U.S. president to have been born in a hospital.

(Source: news.discovery.com)

The largest recorded tsunami was a wave 1,720 feet tall – over a quarter mile high. It struck Lituya Bay, Alaska, in 1958.

(Source: news.discovery.com)

When you take one step, you are using up to 200 muscles.

(Source: news.discovery.com)

Top Ten Mysteries of the Universe

What are those burning questions about the cosmos that still baffle astronomers today?

1. What Are Fermi Bubbles?

No, this is not a rare digestive disorder. The bubbles are massive, mysterious structures that emanate from the Milky Ways center and extend roughly 20,000 light-years above and below the galactic plane. The strange phenomenon, first discovered in 2010, is made up of super-high-energy gamma-ray and X-ray emissions, invisible to the naked eye. Scientists have hypothesized that the gamma rays might be shock waves from stars being consumed by the massive black hole at the center of the galaxy.

2. Rectangular Galaxy

“Look, up in the sky! It’s a…rectangle?” Earlier this year, astronomers spotted a celestial body, roughly 70 million light-years away, with an appearance that is unique in the visible universe: The galaxy LEDA 074886 is shaped more or less like a rectangle. While most galaxies are shaped like discs, three-dimensional ellipses or irregular blobs, this one seems to have a regular rectangle or diamond-shaped appearance. Some have speculated that the shape results from the collision of two spiral-shaped galaxies, but no one knows for now.

3. The Moon’s Magnetic Field

One of the moon’s greatest mysteries—why only some parts of the crust seem to have a magnetic field—has intrigued astronomers for decades, even inspiring the buried mythical “monolith” in the novel and film 2001: A Space Odyssey. But some scientists finally think they may have an explanation. After using a computer model to analyze the moon’s crust, researchers believe the magnetism may be a relic of a 120-mile-wide asteroid that collided with the moon’s southern pole about 4.5 billion years ago, scattering magnetic material. Others, though, believe the magnetic field may be related to other smaller, more recent impacts.

4. Why Do Pulsars Pulse?

Pulsars are distant, rapidly spinning neutron stars that emit a beam of electromagnetic radiation at regular intervals, like a rotating lighthouse beam sweeping over a shoreline. Although the first one was discovered in 1967, scientists have for decades struggled to understand what causes these stars to pulse—and, for that matter, what causes pulsars to occasionally stop pulsing. In 2008, though, when one pulsar suddenly shut off for 580 days, scientists’ observations allowed them to determine that the “on” and “off” periods are somehow related to magnetic currents slowing down the stars’ spin. Astronomers are still at work trying to understand why these magnetic currents fluctuate in the first place.

5. What Is Dark Matter?

Astrophysicists are currently trying to observe the effects of dark energy [link to Fast Forward], which accounts for some 70 percent of the universe. But it’s not the only dark stuff in the cosmos: roughly 25 percent of it is made up of an entirely separate material called dark matter. Completely invisible to telescopes and the human eye, it neither emits nor absorbs visible light (or any form of electromagnetic radiation), but its gravitational effect is evident in the motions of galaxy clusters and individual stars. Although dark matter has proven extremely difficult to study, many scientists speculate that it might be composed of subatomic particles that are fundamentally different from those that create the matter we see around us.

6. Galactic Recycling

In recent years, astronomers have noticed that galaxies form new stars at a rate that would seem to consume more matter than they actually have inside them. The Milky Way, for example, appears to turn about one sun’s worth of dust and gas into new stars every year, but it doesn’t have enough spare matter to keep this up long-term. A new study of distant galaxies might provide the answer: Astronomers noticed gas that had been expelled by the galaxies flowing back in to the center. If the galaxies recycle this gas to produce new stars, it might be a piece of the puzzle in solving the question of the missing raw matter.

7. Where Is All the Lithium?

Models of the Big Bang indicate that the element lithium should be abundant throughout the universe. The mystery, in this case, is pretty straightforward: it doesn’t. Observations of ancient stars, formed from material most similar to that produced by the Big Bang, reveal amounts of lithium two to three times lower than predicted by the theoretical models. New research indicates that some of this lithium may be mixed into the center of stars, out of view of our telescopes, while theorists suggest that axions, hypothetical subatomic particles, may have absorbed protons and reduced the amount of lithium created in the period just after the Big Bang.

8. Is There Anybody Out There?

In 1961, astrophysicist Frank Drake devised a highly controversial equation: By multiplying together a series of terms relating to the probability of extraterrestrial life (the rate of star formation in the universe, the fraction of stars with planets, the fraction of planets with conditions suitable for life, etc.) he surmised that the existence of intelligent life on other planets is extremely likely. One problem: Roswell conspiracy theorists notwithstanding, we haven’t heard from any aliens to date. Recent discoveries of distant planets that could theoretically harbor life, though, have raised hopes that we might detect extraterrestrials if we just keep looking.

9. How Will the Universe End? [Warning, Potential Spoiler Alert!]

We now believe the universe started with the Big Bang. But how will it end? Based on a number of factors, theorists conclude that the fate of the universe could take one of several wildly different forms. If the amount of dark energy is not enough to resist the compressing force of gravity, the entire universe could collapse into a singular point—a mirror image of the Big Bang, known as the Big Crunch. Recent findings, though, indicate a Big Crunch is less likely than a Big Chill, in which dark energy forces the universe into a slow, gradual expansion and all that remains are burned-out stars and dead planets, hovering at temperatures barely above absolute zero. If enough dark energy is present to overwhelm all other forces, a Big Rip scenario could occur, in which all galaxies, stars and even atoms are torn apart.

10. Across the Multiverse

Theoretical physicists speculate that our universe may not be the only one of its kind. The idea is that our universe exists within a bubble, and multiple alternative universes are contained within their own distinct bubbles. In these other universes, the physical constants—and even the laws of physics—may differ drastically. Despite the theory’s resemblance to science fiction, astronomers are now looking for physical evidence: Disc-shaped patterns in the cosmic background radiation left over from the Big Bang, which could indicate collisions with other universes.


Giraffes and humans have the same number of bones in their necks: seven.

(Source: news.discovery.com)

Top 10 Amazing Moon Facts

1. The Big Whack

The moon formed as a result of a collision known as the Giant Impact or the Big Whack, scientists figure. It went like this: A giant Mars-sized object hit Earth 4.6 billion years ago shortly after the birth of the sun and the solar system. A cloud of vaporized rock was kicked up (a mix of Earth and the other object) and went into orbit around Earth. The cloud cooled and condensed into a ring of small, solid bodies, which then gathered together, forming the moon.

2. Earth makes the moon rise

Each day, though not at the same time, the moon comes up in the East and goes down in the West — much like the sun and other stars and for the same reason Earth rotates, on its axis, toward the East, pulling celestial objects into view and then forcing them to slip away. The moon also makes an orbital trip around Earth once every 29.5 days. In the sky, this gradual movement is eastward, though it’s not perceptible during any given observing session. It is, however, why the moon rises later each day, by about 50 minutes on average. That also explains why the moon sometimes rises in the evening and us up during the night, while at other times it’s up only or mostly during the day.

3. No dark side

Contrary to what you might have heard, there is no “dark side” of the moon. There is, however, a “far side” that we can’t see from Earth. Here’s why: Long ago, the Earth’s gravitational effects slowed the moon’s rotation about its axis. Once the moon’s rotation slowed enough to match its orbital period (the time it takes the moon to go around Earth) the effect stabilized. So the moon goes around the Earth once and spins on its axis once, all in the same amount of time, and it shows us just one face the whole time.

4. Gravity is much weaker

The moon is about 27 percent the size of Earth and far less massive. Gravity on the moon is only about 1/6 of that on Earth. If you drop a rock on the moon, it falls more slowly (and astronauts can hope much higher). If you weigh 150 pounds on Earth, you’d weigh 25 pounds on the moon. 

5. Bigger and smaller full moons

The moon’s orbit around Earth is an oval, not a circle, so the distance between the center of Earth and the moon’s center varies throughout each orbit. At perigee (PEHR uh jee), when the moon is closest to Earth, that distance is 225,740 miles (363,300 kilometers). At apogee (AP uh jee), the farthest position, the distance is 251,970 miles (405,500 kilometers).

6. Pockmarked history

The craters on the moon reveal its violent history. Because there is almost no atmosphere and little activity inside the moon, the crater trace a record of impacts back billions of years (unlike Earth, which would have been just as violent back then, but the craters have all been weathered away or folded back into the planet). By dating the moon’s many craters, scientists figured out that the moon (and Earth) underwent a Late Heavy Bombardment around 4 billion years ago. The latest thinking on this pummeling is that life may have survived it, if biology had gotten a foothold that early.

7. Not round

The moon is not round (or spherical). Instead, it’s shaped like an egg. If you go outside and look up at the moon, one of the small ends is pointing right at you. And the moon’s center of mass is not at the geometric center of the satellite; it’s about 1.2 miles (2 kilometers) off-center. Earth, likewise, bulges in its midsection.

8. Caution! Moonquakes

Apollo astronauts used seismometers during their visits to the moon and discovered that the gray orb isn’t a totally dead place, geologically speaking. Small moonquakes, originating several miles (kilometers) below the surface, are thought to be caused by the gravitational pull of Earth. Sometimes tiny fractures appear at the surface, and gas escapes.

9. Tugging on the oceans

Tides on Earth are caused mostly by the moon (the sun has a smaller effect). Here’s how it works: The moon’s gravity pulls on Earth’s oceans. High tide aligns with the moon as Earth spins underneath. Another high tide occurs on the opposite side of the planet because gravity pulls Earth toward the moon more than it pulls the water.

10. Ciao, Luna!

As you read this, the moon is moving away from us. Each year, the moon steals some of Earth’s rotational energy, and uses it to propel itself about 1.6 inches (4 centimeters) higher in its orbit. Researchers say that when it formed about 4.6 billion years ago, the moon was about 14,000 miles (22,530 kilometers) from Earth. It’s now more than 280,000 miles, or 450,000 kilometers away. Meanwhile, Earth’s rotation rate is slowing down — our days are getting longer and longer. Eventually, our planet’s tidal bulges will be assembled along an imaginary line running through the centers of both Earth and the moon, and our planetary rotational change will pretty much cease. Earth’s day will be a month long. When this happens, billions of years from now, the terrestrial month will be longer — about 40 of our current days — because during all this time the moon will continue moving away.;

(Source: livescience.com)

Top 10 Biggest Brain Damaging Habits

1. No Breakfast

People who do not take breakfast are going to have a lower blood sugar level.This leads to an insufficient supply of nutrients to the brain causing brain degeneration.

2. Overreacting

It causes hardening of the brain arteries, leading to a decrease in mental power.

3. Smoking

It causes multiple brain shrinkage and may lead to Alzheimer disease.

4. High Sugar consumption

Too much sugar will interrupt the absorption of proteins and nutrients causing malnutrition and may interfere with brain development.       

5. Air Pollution

The brain is the largest oxygen consumer in our body. Inhaling polluted air decreases the supply of oxygen to the brain, bringing about a decrease in brain efficiency.

6. Sleep Deprivation

Sleep allows our brain to rest. Long term deprivation from sleep will accelerate the death of brain

7. Head covered while sleeping

Sleeping with the head covered, increases the concentration of carbon dioxide and decrease concentration of oxygen that may lead to brain damaging effects.

8. Working your brain during illness

Working hard or studying with sickness may lead to a decrease in effectiveness of the brain as well as damage the brain.            

9. Talking Rarely

Intellectual conversations will promote the efficiency of the brain.

10. Lacking in stimulating thoughts

Thinking is the best way to train our brain, lacking in brain stimulation thoughts may cause brain shrinkage.

20 Things You Didn’t Know About Fire

1  Fire is an event, not a thing. Heating wood or other fuel releases volatile vapors that can rapidly combust with oxygen in the air; the resulting incandescent bloom of gas further heats the fuel, releasing more vapors and perpetuating the cycle.

2  Most of the fuels we use derive their energy from trapped solar rays. In photosynthesis, sunlight and heat make chemical energy (in the form of wood or fossil fuel); fire uses chemical energy to produce light and heat.

3  So a bonfire is basically a tree running in reverse.

4  Assuming stable fuel, heat, and oxygen levels, a typical house fire will double in size every minute.

5  Earth is the only known planet where fire can burn. Everywhere else: Not enough oxygen.

6  Conversely, the more oxygen, the hotter the fire. Air is 21 percent oxygen; combine pure oxygen with acetylene, a chemical relative of methane, and you get an oxyacetylene welding torch that burns at over 5,500 degrees Fahrenheit—the hottest fire you are likely to encounter.

7  Oxygen supply influences the color of the flame. A low-oxygen fire contains lots of uncombusted fuel particles and will give off a yellow glow. A high-oxygen fire burns blue.

8  So candle flames are blue at the bottom because that’s where they take up fresh air, and yellow at the top because the rising fumes from below partly suffocate the upper part of the flame.

9  Fire makes water? It’s true. Place a cold spoon over a candle and you will observe the water vapor condense on the metal…

10 …because wax—like most organic materials, including wood and gasoline—contains hydrogen, which bonds with oxygen to make H2O when it burns. Water comes out your car’s tailpipe, too.

11  We’ve been at this a long time: Charred bones and wood ash indicate that early hominids were tending thefirst intentional fires more than 400,000 years ago.

12  Nature’s been at it awhile, too. A coal seam about 140 miles north of Sydney, Australia, has been burning by some estimates for 500,000 years.

13  The ancient Greeks started fire with concentrated sunlight. A parabolic mirror that focuses solar rays is still used to ignite the Olympic torch.

14  Every 52 years, when their calendar completed a cycle, the Aztecs would extinguish every flame in the empire. The high priest would start a new fire on the ripped-open chest of a sacrificial victim. Fires fed from this flame would be distributed throughout the land.

15  Good burn: The 1666 Great Fire of London destroyed 80 percent of the city but also ended an outbreak of bubonic plague that had killed more than 65,000 people the previous year. The fire fried the rats and fleas that carried Yersinia pestis, the plague-causing bacterium.

16  The Peshtigo Fire in Wisconsin was the second deadliest blaze in United States history, taking 1,200 lives—four times as many as the Great Chicago Fire. Both conflagrations broke out on the same day: October 8, 1871.

17  America’s deadliest fire took place April 27, 1865, aboard the steamship Sultana. Among other passengers were 1,500 recently released Union prisoners traveling home up the Mississippi when the boilers exploded. The ship was six times over capacity, which helps explain the death toll of 1,547.

18  The Black Dragon Fire of 1987, the largest wildfire in modern times, burned some 20 million acres across China and the Soviet Union, an area about the size of South Carolina.

19  Spontaneous combustion is real. Some fuel sources can generate their own heat—by rotting, for instance. Pistachios have so much natural oil and are so prone to heat-generating fat decomposition that the International Maritime Dangerous Goods Code regards them as dangerous.

20  Haystacks, compost heaps, and even piles of old newspapers and magazines can also burst into flame. A good reason to recycle DISCOVER when you are done.

10 Fascinating Facts about the Brain

protagonistdjphaw:

1. The average brain weighs around 3lbs.

2. Our skin weighs roughly twice as much as our brain.

3. The brain is the fattiest organ we have (It is made up of 60% fat).

4. We can’t feel pain in our brain as there are no pain receptors.

5. When we’re awake, our brain generates enough energy to power a light bulb.

6. High levels of stress can alter our brain functioning and structure.

7. Every time we have a new thought we’re creating a new pathway in the brain.

8. Scent has the strongest emotional connection of any trigger in the brain.

9. The average person is believed to have around 70,000 thoughts a day.

10. The brains of people known as supertasters are more sensitive to taste in foods and drinks.

(Source: onlinecounsellingcollege)


The Freakiest Places in the Solar System

1. WEIRDEST ROTATION

The Saturnian moon Hyperion is a lumpy thing, measuring about 255 x 163 x 137 miles in diameter along its three axes. Since moons of this size typically have enough gravity to pull them into a spherical shape, astronomers suggest that it may be a fragment of a larger moon that was shattered by an impact. The planet’s odd shape explains why the planet is, as Baker and Ratcliff put it, “a tumbling chaotic mess.” Most large moons are tidally locked, meaning that the same face of the moon always faces its planet. But Hyperion’s bizarre shape prevents such locking, because the gravitational torques from Saturn and the moon Titan tug at it unevenly.

2.GRANDEST CANYON

Picture a canyon that stretches from San Francisco to Washington DC, and you’ll have an idea of the scope of Valles Marineris on Mars. 

This enormous gorge was first spotted by the NASA spacecraft Mariner 9 in 1972, and the canyon was named in the spacecraft’s honor. It stretches 2,485 miles across the planet’s surface, and reaches depths of 6.2 miles (for comparison, our Grand Canyon plunges 1.1 miles down at its deepest point). Valles Marineris is thought to be a rift valley, formed by uplift when hot material from the Mars’s mantle bubbled up and stretched the planet’s crust.


The result: A rotation that’s impossible to predict. “The days are never the same,” the authors write. “Not only does the rotation rate (the length of day) vary erratically, but Hyperion’s north pole continually points to a different location in space.” Astronomers know the equation to predict the moon’s rotational motion, but small uncertainties in measurements of the moon’s initial location or velocity turn into large uncertainties over time. For Hyperion, the authors say, “it is completely impossible to predict the direction of its spin axis after about 300 days—it could be pointed anywhere!”

3.STINKIEST PLACE

The Jovian moon Io is fascinating from a planetary science perspective—it’s the most volcanically active place in our solar system, and its surface is pockmarked with volcanic craters. But it wouldn’t be much fun to visit. Baker and Ratcliff write that “Jupiter’s moon Io smells like a jumbo rotten egg.” The stink is due to hydrogen sulfide on Io’s surface and in its upper atmosphere, and the moon owes its distinctive yellow and red coloration to sulfur compounds. 

Volcanic eruptions are quite common on Io, and they constantly refresh the atmosphere’s supply of sulfur gas. The moon is highly active because it travels around Jupiter in a slightly elliptical orbit. As the moon repeatedly dances closer to and farther from the giant planet, Jupiter’s gravity produces tidal flexing in the moon’s interior that heats its mantle and causes violent explosions. In 2007 NASA’s New Horizons spacecraft flew by Io and observed a volcanic eruption with sulfur plumes that stretched 180 miles above the surface. The largest volcanic eruptions on Earth reach about 12 miles high.

4.LONGEST-LIVED STORM

This storm shows no inclination of blowing itself out. Jupiter’s Great Red Spot was first observed by the Italian astronomer Giovanni Cassini in 1665; while observations were sporadic in the 18th and early 19th centuries, many astronomers think the storm has been roaring for the 345 years since it was first seen. The immense storm is the size of three Earths, and the winds reach speeds topping 400 miles per hour. 

How has it kept churning through the centuries? Baker and Ratcliff explain that its energy comes from Jupiter’s interior and smaller vortices. “Remarkably, Jupiter’s interior supplies 70 percent more energy to the cloud tops than the planet receives from the Sun,” they write. “Like a giant air compressor, gravitational contraction generates intense pressures and heat deep inside the planet. Powerful thunderstorms in Jupiter’s atmosphere channel much of this heat to the cloud tops.” Smaller storms are devoured by the Great Red Spot, which allows it to roar on.

(Source: discovermagazine.com)

20 Things You Didn’t Know About Time

1  “Time is an illusion. Lunchtime doubly so,” joked Douglas Adams in The Hitchhiker’s Guide to the Galaxy. Scientists aren’t laughing, though. Some speculative new physics theories suggest that time emerges from a more fundamental—and timeless—reality.

2  Try explaining that when you get to work late. The average U.S. city commuter loses 38 hours a year to traffic delays.

3  Wonder why you have to set your clock ahead in March? Daylight Saving Time began as a joke by Benjamin Franklin, who proposed waking people earlier on bright summer mornings so they might work more during the day and thus save candles. It was introduced in the U.K. in 1917 and then spread around the world.

4  Green days. The Department of Energy estimates that electricity demand drops by 0.5 percent during Daylight Saving Time, saving the equivalent of nearly 3 million barrels of oil.

5  By observing how quickly bank tellers made change, pedestrians walked, and postal clerks spoke, psychologists determined that the three fastest-paced U.S. cities are Boston, Buffalo, and New York.

6  The three slowest? Shreveport, Sacramento, and L.A.

7  One second used to be defined as 1/86,400 the length of a day. However, Earth’s rotation isn’t perfectly reliable. Tidal friction from the sun and moon slows our planet and increases the length of a day by 3 milli­seconds per century.

8  This means that in the time of the dinosaurs, the day was just 23 hours long.

9  Weather also changes the day. During El Niño events, strong winds can slow Earth’s rotation by a fraction of a milli­second every 24 hours.

10  Modern technology can do better. In 1972 a network of atomic clocks in more than 50 countries was made the final authority on time, so accurate that it takes 31.7 million years to lose about one second.

11  To keep this time in sync with Earth’s slowing rotation, a “leap second” must be added every few years, most recently this past New Year’s Eve.

12  The world’s most accurate clock, at the National Institute of Standards and Technology in Colorado, measures vibrations of a single atom of mercury. In a billion years it will not lose one second.

13  Until the 1800s, every village lived in its own little time zone, with clocks synchronized to the local solar noon.

14  This caused havoc with the advent of trains and timetables. For a while watches were made that could tell both local time and “railway time.”

15  On November 18, 1883, American railway companies forced the national adoption of standardized time zones.

16  Thinking about how railway time required clocks in different places to be synchronized may have inspiredEinstein to develop his theory of relativity, which unifies space and time.

17  Einstein showed that gravity makes time run more slowly. Thus airplane passengers, flying where Earth’s pull is weaker, age a few extra nano­seconds each flight.

18  According to quantum theory, the shortest moment of time that can exist is known as Planck time, or 0.0000000000000000000000000000000000000000001 second.

19  Time has not been around forever. Most scientists believe it was created along with the rest of the universe in the Big Bang, 13.7 billion years ago.

20  There may be an end of time. Three Spanish scientists posit that the observed acceleration of the expanding cosmos is an illusion caused by the slowing of time. According to their math, time may eventually stop, at which point everything will come to a standstill.


6 Weird Facts About Gravity

Gravity: You don’t know what you’ve got ‘til it’s gone

Here on Earth, we take gravity so for granted that it took an apple falling from a tree to trigger Isaac Newton’s theory of gravitation. But gravity, which draws objects together in proportion to their mass, is about much more than fallen fruit. Read on for some of the strangest facts about this universal force.

1. It’s all in your head

Gravity may be pretty consistent on Earth, but our perception of it isn’t. According to research published in April 2011 in the journal PLoS ONE, people are better at judging how objects fall when they’re sitting upright versus lying on their sides.

The finding means that our perception of gravity may be less based on visual cues of gravity’s real direction and more rooted in the orientation of the body. The findings may lead to new strategies to help astronauts deal with microgravity in space.

2. Coming down to Earth is tough

Speaking of astronauts, their experience has shown that a switch to weightlessness and back can be tough on the body. In the absence of gravity, muscles atrophy and bones likewise lose bone mass. According to NASA, astronauts can lose 1 percent of their bone mass per month in space.

When astronauts come back to Earth, their bodies and minds need time to recover. Blood pressure, which has equalized throughout the body in space, has to return to an Earthly pattern in which the heart must work hard to keep the brain nourished with blood. Occasionally, astronauts struggle with that adjustment. In 2006, astronaut Heidemarie Stefanyshyn-Piper collapsed at a welcome-home ceremony the day after returning from a Space Shuttle mission to the International Space Station.

The mental readjustment can be just as tricky. In 1973, Skylab 2 astronaut Jack Lousma told Time magazine that he’d accidentally smashed a bottle of aftershave in his first days back from a month-long sojourn in space. He’d let go of the bottle in mid-air, forgetting that it would crash to the ground rather than just float there

3. For weight loss, try Pluto

Pluto may no longer be a planet, but it’s still a good bet for lightening up. A 150-pound (68 kilogram) person would weigh no more than 10 pounds (4.5 kg) on the dwarf planet. The planet with the most crushing gravity, on the other hand, is Jupiter, where the same person would weigh more than 354 pounds (160.5 kg).

The planet humans are most likely to visit, Mars, would also leave explorers feeling light-footed. Mars’ gravitational pull is only 38 percent that of Earth’s, meaning a 150-pound person would feel like they weigh about 57 pounds (26 kg).

4. Gravity is lumpy

Even on Earth, gravity isn’t entirely even. Because the globe isn’t a perfect sphere, its mass is distributed unevenly. And uneven mass means slightly uneven gravity.

One mysterious gravitational anomaly is in the Hudson Bay of Canada (shown above). This area has lower gravity than other regions, and a 2007 study finds that now-melted glaciers are to blame.

The ice that once cloaked the area during the last ice age has long since melted, but the Earth hasn’t entirely snapped back from the burden. Since gravity over an area is proportional to the mass atop that region, and the glacier’s imprint pushed aside some of the Earth’s mass, gravity is a bit less strong in the ice sheet’s imprint. The slight deformation of the crust explains 25 percent to 45 percent of the unusually low gravity; the rest may be explained by a downward drag caused the motion of magma in Earth’s mantle (the layer just beneath the crust), researchers reported in the journal Science.

5. Without gravity, some bugs get tougher

Bad news for space cadets: Some bacteria become nastier in space. A 2007 study published in the journal Proceedings of the National Academy of Sciences found that salmonella, the bacteria that commonly causes food poisoning, becomes three times more virulent in microgravity. Something about the lack of gravity changed the activity of at least 167 salmonella genes and 73 of its proteins. Mice fed the gravity-free salmonella got sick faster after consuming less of the bacteria.

In other words, Michael Crichton’s “The Andromeda Strain” had it wrong: The danger of infection in space may not come from space bugs. It’s more likely our own bugs grown stronger would strike us.

6. Black holes at the center of galaxies

Named because nothing, not even light, can escape their gravitational clutches, black holes are some of the most destructive objects in the universe. At the center of our galaxy is a massive black hole with the mass of 3 million suns. Scarier thought? It might be “just resting,” according Kyoto University scientist Tatsuya Inui.

The black hole isn’t really a danger to us Earthlings — it’s both far away and it’s remarkably calm. But sometimes it does put on a show: Inui and colleagues reported in 2008 that the black hole sent out a flare of energy 300 years ago. Another study, released in 2007, found that several thousand years ago, a galactic hiccup sent a small amount of matter the size of Mercury falling into the black hole, leading to another outburst.

The black hole, named Sagittarius A*, is dim compared with other black holes.

“This faintness implies that stars and gas rarely get close enough to the black hole to be in any danger,” Frederick Baganoff, a researcher at the Massachusetts Institute of Technology who was involved with the 2007 study, told LiveScience’s sister site SPACE.com. “The huge appetite is there, but it’s not being satisfied.”

20 Things You Didn’t Know About Water

1  Water is everywhere—there are 332,500,000 cubic miles of it on the earth’s surface. But less than 1 percent of it is fresh and accessible, even when you include bottled water.

2  And “fresh” can be a relative term. Before 2009, federal regulators did not require water bottlers to remove E. coli.

3  Actually, E. coli doesn’t sound so bad. In 1999 the Natural Resources Defense Council found that one brand of spring water came from a well in an industrial parking lot near a hazardous waste dump.

4  Cheers! The new Water Recovery System on the International Space Station recycles 93 percent of astronauts’ perspiration and urine, turning it back into drinking water.

5  Kurdish villages in northern Iraq are using a portable version of the NASA system to purify water from streams and rivers, courtesy of the relief group Concern for Kids.

6  Ice is a lattice of tetra­hedrally bonded molecules that contain a lot of empty space. That’s why it floats.

7  Even after ice melts, some of those tetrahedrons almost always remain, like tiny ice cubes 100 molecules wide. So every glass of water, no matter what its temperature, comes on the rocks.

8  You can make your own water by mixing hydrogen and oxygen in a container and adding a spark. Unfortunately, that is the formula that helped destroy the Hindenburg.

9  Scientists have a less explosive recipe for extracting energy from hydrogen and oxygen. Strip away electrons from some hydrogen molecules, add oxygen molecules with too many electrons, and bingo! You get an electric current. That’s what happens in a fuel cell.

10  Good gardeners know not to water plants during the day. Droplets clinging to the leaves can act as little magnifying glasses, focusing sunlight and causing the plants to burn.

11  Hair on your skin can hold water droplets too. A hairy leg may get sunburned more quickly than a shaved one.

12  Vicious cycle: Water in the stratosphere contributes to the current warming of the earth’s atmosphere. That in turn may increase the severity of tropical cyclones, which throw more water into the stratosphere. That’s the theory, anyway.

13  The slower rate of warming in the past decade might be due to a 10 percent drop in stratospheric water. Cause: unknown.

14  Although many doctors tell patients to drink eight glasses of water a day, there is no scientific evidence to support this advice.

15  The misinformation might have come from a 1945 report recommending that Americans consume about “1 milliliter of water for each calorie of food,” which amounts to 8 or 10 cups a day. But the report added that much of that water comes from food—a nuance many people apparently missed.

16  Call waterholics anonymous: Drinking significantly more water than is needed can cause “water intoxication” and lead to fatal cerebral and pulmonary edema. Amateur marathon runners have died this way.

17  Scientists at Oregon State University have identified vast reservoirs of water beneath the ocean floor. In fact, there may be more water under the oceans than in them.

18  Without water, ocean crust would not sink back into the earth’s mantle. There would be no plate tectonics, and our planet would probably be a lot like Venus: hellish and inert.

19  At the other end of the wetness scale, planet GJ 1214b, which orbits a red dwarf star, may be almost entirely water.

20  Recent evidence suggests that when the solar system formed 4.5 billion years ago, comets had liquid cores. If so, life may have started in a comet.

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