DECEMBER, 1996
Water on the Moon
Scientists may have found ice on the surface of the Moon. If so,this water could be used in the future to produce oxygen for a Moon colony or rocket fuel for space travel.
In 1994, a spacecraft named Clementine was launched. It orbited the Moon for 4 months, and mapped its surface using radar. Scientists believe they discovered ice in a huge, deep crater at the Moon's south pole. Sunlight never reaches much of the south pole. Temperatures in the shadows there may be as low as minus 233 degrees Celsius (minus 387 degrees Fahrenheit.) Scientists think the ice came from comets, and became trapped in the cold, dark crater. On other parts of the Moon, any water in direct sunlight evaporated into space long ago.
Although scientists think the material is probably water ice, they can not be sure. Especially since the ice is mixed with dirt and rock, and is not pure. Another spacecraft, the Lunar Prospector, will be sent to the Moon next September. Maybe then we will learn more.
More about Mars
Eleven meteorites from Mars have been found so far here on Earth, and there may be others. A Cornell University astronomer says that rocks from Mars head towards Earth all the time. Most of them miss, and most of the rest are so small that they burn up completely in the Earth's atmosphere. Of the few that reach the surface, most splash into the ocean and dissappear. But there may be others around just waiting to be discovered.
One of the known meteorites, ALH 84001, made the news last summer. (See Science in the News, August, 1996, below.) NASA scientists announced that it may show signs of ancient life on Mars. That meteorite is about 3.6 billion years old. British scientists now believe that another meteorite, called EETA 79001, may also have held ancient life. It is much younger, only 180 million years old. Studies of these meteorites are continuing, and scientists hope future Mars missions will give us more information.
NASA plans to send many new spacecraft to Mars over the next decade. Two will be launched every 26 months, during the "launch window," when the positions of the planets are favorable. The final mission, in 2003 or 2005, will bring samples of Martian rocks back to Earth.
The first U.S. spacecraft, the Mars Global Surveyor, was launched on November 7 and will reach Mars next September. It will orbit the planet to study its atmosphere, map the surface and identify interesting areas to explore.
The second U.S. craft, the Mars Pathfinder, was launched on December 5, two days late due to bad weather and a computer problem. It will land on the rocky surface next July 4. This will be the first time a lander will go directly to the surface without going into orbit first. The lander will be slowed by a parachute as it descends through the Martian atmosphere. Then the parachute will fall off, and giant air bags will inflate to soften the landing. The bags will deflate, the ship will open, and two ramps will pop out. A six-wheeled rover, named Sojourner, will drive down to explore the surface. It will sample the soil and rocks, and send back information and pictures. The pictures will be available on the Internet.
A Russian spacecraft, launched in November, crashed back to Earth after one of the booster rockets failed. It carried four landing vehicles, and equipment and experiments from many different countries, including the U.S. It also carried about 200 grams of radioactive plutonium, sealed in strong containers, which would have been used to power the landers. The plutonium is believed to have landed in the Southern Pacific Ocean, but there is some concern over its possible release into the environment.
NOVEMBER, 1996
Birds do badly after oil spills
You may have seen pictures of sea birds caught in an oil spill, and covered with black goo. Many of these birds are captured and cleaned. When they seem healthly again, they are released back to the wild. Helping the birds is very expensive. After the huge Exxon Valdex oil spill in Alaska in 1989, it cost $41 million to help 800 birds and a few hundred sea otters. Many other animals could not be helped. An estimated 36,000 birds and 3000 otters died.
It makes us all feel better to see some of these animals being helped. But recent studies show that the birds do not do well after returning home. Even though they seem healthy when released, most die within several months. Many die within days. The scientists who did the study now wonder if cleaning the birds is worth the cost, or whether the money should be spent instead on preventing oil spills. Other scientists say the cleanups are worth it. They hope to keep improving the birds' care so that more of them can survive.
Feathered dinosaurs?
Chinese scientists recently discovered the fossil of a small dinosaur that looks like it had feathers. The feathers were short, like down, and ran in a stripe along its back and tail. The animal lived between 120 million and 140 million years ago, in what is now northeast China. Fossils of ancient birds, clearly showing impressions of their feathers, were found in the same area last year. Finding a fossil with feathers is very rare because feathers are so fragile and usually break down quickly.
Scientists are now studying the new fossils, which may raise more questions than they answer.
The theory that birds evolved from dinosaurs has been around since the 1860's. Many scientists now accept this theory. Studies beginning in the 1970's show similar body structure (anatomy) between archaeopteryx, one of the first known birds, and a group of dinosaurs called coelurosaurs.
Other scientists do not believe birds came from dinosaurs. It's possible the impressions on the dinosaur fossil came from something else, like the remains of frayed scales. Also, there are problems with the time lines. Archaeopteryx lived 145 million to 150 million years ago. The dinosaurs most like archaeopteryx lived 75 million years later. Newly discovered fossils show birds, about 140 million years old, which looked much more modern than archaeopteryx. This leads some scientists to believe that birds and dinosaurs both came from an earlier ancestor, some pre-dinosaur reptile. The debate is likely to continue for a long time.
OCTOBER, 1996
Some Good News About Chocolate
You certainly can't call chocolate a "health food," but it may not be all bad, either.
Many high-fat foods spoil unless they are refrigerated. At room temperature, these fats "oxidize" and quickly become rancid. Chocolate, a fatty food, can stay fresh at room temperature for a long time. Scientists have discovered that cocoa contains chemicals called antioxidants, which slow down oxidation of the fats. The same antioxidants which preserve the food, also help us. Some of the symptoms and diseases of aging are caused by unwanted oxidation of molecules in our body. The antioxidants in many fruits and vegetables, and vitamin tablets, help protect us from the effects of oxidation. The antioxidants in chocolate may do the same.
Three New Reports on Cigarette Smoking
1) You may have heard warnings that smoking cigarettes stunts your growth. Now, a new study proves it really does stunt the growth and development of your lungs. More than 10,000 young people, ages 10-18, were included in the 15 year study. Those who smoked suffered far more respiratory illness than those who did not. The problems included bronchitis, wheezing, chronic coughing and reduced breathing capacity. The more cigarettes smoked each day and the longer smoking continued, the greater the lung damage. The study was reported in "The New England Journal of Medicine."
2) Scientists have discovered how a chemical in cigarette smoke can cause cancer. The chemical, benzo(a)pyrene, damages an important cancer-preventing gene. This gene, called p53, normally helps control cell growth. When the gene mutates (or changes), cells can grow and divide out of control. About 60% of lung cancers have mutations in the p53 gene. Although there are many strong links between smoking and cancer, this is the first laboratory evidence of how tobacco can cause cancer in humans. The study was published in the journal "Science."
3) Two other new studies now link smoking to blindness. Heavy smokers are twice as likely as non-smokers to develop macular degeneration. It is the leading cause of vision loss in older people.
In spite of information on the dangers of tobacco, more than 3,000 young people begin smoking each day in the United States alone.
SEPTEMBER, 1996
Total Eclipse of the Moon
On the night of September 26-27, people in much of the world will see a total lunar eclipse. If you live in North America, this is your last chance for quite awhile; the next total eclipse will be January 20, 2000.
A partial lunar eclipse occurs when part of the Moon passes through the shadow of the Earth. During a total eclipse, the Moon is completely in the Earth's shadow.
This event begins at 8:12 pm (all times are EDT), when the Moon enters the penumbra (the very edge of the Earth's shadow.) Nothing will be visible from Earth until about 8:40 pm, when a faint shadow may appear and begin crossing the Moon's surface. The partial eclipse will begin at 9:12 pm. As time passes, more and more of the Moon will be eclipsed, until the beginning of the total eclipse at 10:19 pm. At 11:29 pm, the total eclipse will end and the Moon will begin moving out of the Earth's shadow. The partial eclipse will end at 12:36 pm.
During a total eclipse, the appearance of the Moon can vary from a bright orange or reddish color, to darker red, grey or brown. Sometimes it appears so dark that it is almost invisible.
The Moon produces no light of it's own. "Moonlight" is actually sunlight that has been reflected from the Moon's surface. During a total eclipse, the only sunlight to reach the Moon has been scattered through the Earth's atmosphere. The color and brightness of the eclipsed moon can tell us how much dust is in the upper atmosphere. During last April's eclipse, the Moon appeared a bright reddish orange. There was little dust in the air. In 1992 and 1993, the Moon appeared dark reddish-brown during eclipses. At that time, the atmosphere was full of particles and dust, which had come from the 1991 volcanic eruption of Mt. Pinatubo.
As an added treat, Saturn will be brightly visible very close to the Moon during this eclipse. Its position will depend on the time, and your location. In North America, look for Saturn to the lower right of the Moon.
Third Branch of Life on Earth?
Until recently, scientists divided all life on Earth into two main groups - the Prokarya (bacteria) and the Eucarya (all fungi, plants and animals.) Now it seems that there is a third group, called Archaea. The archaea microbes were first found in extreme environments, like the hot springs in Yellowstone National Park. Now scientists are finding these microbes are much more common than they had thought. Some believe that half of the Earth's biomass may belong to the archaea group. (Biomass is the weight of living things.)
Why do some scientists believe that archaea is a third main branch of life and not just a part of the procarya? In 1982, microbes called Methanococcus jannaschii were discovered living near volcanic vents, deep on the ocean floor. Scientists have now mapped out all the genes of M. jannaschii. Some of the genes are similar to those of eucaryotes while others are more like the genes of bacteria. Suprisingly, two thirds of the genes were different from anything the scientists had seen before.
Many people are now working to map out the genes of other organisms. Most scientists are waiting for more information before agreeing that archaea belongs in a separate group.
AUGUST, 1996
Ancient Life on Mars?
Don't look for little green men, but NASA scientists have found evidence that simple life may have existed on Mars 3.6 billion years ago. Much more work needs to be done before they can be sure. There may be other explanations for what they see.
The evidence was found in a meteorite, discovered in 1984 in Antarctica. Why do scientists believe the meteorite is from Mars? In 1976, the Viking spacecraft landed on Mars and took samples of the planet's atmosphere. Gas trapped in small holes inside this meteorite matches the gas in the Martian atmosphere.
What makes the scientists think there may have been ancient life on Mars?
(1) The meteorite contains very tiny tube and egg-shaped objects. These look very
similar to fossils of ancient Earth bacteria.
(2) There were certain kinds of organic chemicals in the rock, called PAHs
(polycyclic hydrocarbons.) On Earth, PAHs are often formed when plants die and decay.
(3) Chemicals called carbonates were found. These may have formed when water,
containing dissolved carbon dioxide, flowed through cracks in the rocks. Liquid water is
necessary for life as we know it on Earth.
(4) Two other chemicals, iron sulfide and magnetite, were also found. Many
bacteria on Earth produce these.
Separately, each of these things could have causes other than living organisms. However, they were all found very, very close to each other. When taken together, NASA scientists believe that the most likely cause is ancient life.
Three spacecraft are scheduled to launch this fall, headed for Mars. Maybe one of them will help give us an anwer. In the meantime, the debate will continue.
JULY, 1996
Keep Your Eye On The Ball
A recent study by British psychologists may help improve your performance. The study found that, in games where a player must intercept a moving ball, it is not necessary to predict exactly where the ball will land. Instead, successful fielders run at a speed which keeps their view of the ball at a constant angle. That angle should be somewhere between 0° (straight ahead) and 90° (straight up). The player will miss the ball if the angle reaches either 0° or 90°. So, keep your eye on that ball!
More Hours In Your Day
Have you ever been so busy that you wished for more hours in the day? Well, you probably haven't noticed, but the days are actually getting slightly longer all the time!
For many years, physicists thought that tides caused by the moon have been slowing the Earth's rotation and increasing the length of our day. As the Earth slows, its momentum (or energy) is transferred to the moon, which speeds up and moves farther away. Measurements have shown that the distance between the moon and Earth is actually growing by 3.8 cm (1.5 inches) per year.But getting proof that the Earth's rotation has slowed down is much harder.
Now, scientists studying rare sedimentary rocks, called tidal rhythmites,
believe they have found that proof. The rhythmites were formed when tides
deposited alternating layers of light and dark colored sediments along ancient
shorelines. By measuring the layers, the scientists calculated that 900 million
years ago, there were 18.2 hours in each day,and 481 days in a year.
(I don't
know about you, but I can't wait a billion years for a 30 hour day. I could use
the extra time now.)
JUNE, 1996
Once In A Blue Moon? - It Will Happen In June!
It only happens once in a blue moon! We use this expression for something that happens so rarely, it almost never occurs. But just what is a "blue moon," and how often does it really happen?
A blue moon is simply the second of two full moons that occur in a single calendar month. How can there be more than one full moon in a month? A lunar month is 29.53 days, so there is a full moon every 29.53 days. There are 365.24 days in a year. If you divide 365.24 days per year by 29.53 days per lunar month, you see that there are 12.37 full moons each year. So, once every 2.72 years, there is a blue moon. Since the number of days in calendar months varies from 28 to 31, we get a blue moon once every 2 years and 7, 8, 9 or 10 months.
The blue moon of June will occur on June 30, at 11:58 pm EDT.
What Could Possibly Be Scarier Than T. Rex?
Tyrannosaurus rex, the huge meat-eater that lived in North America 65 million years ago, may soon be displaced as king in the hearts and minds of dinosaur lovers. In the Sahara desert of southeastern Morocco, paleontologists have discovered the gigantic skull of a carnivorous dinosaur called Carcharodontosaurus saharicus. The name means "shark-toothed reptile from the Sahara." The skull was 5 feet 4 inches long, with 5 inch long teeth, and the dinosaur was about 45 feet long. It lived 90 million years ago.
As if that was not frightening enough, try to imagine meeting these other recent discoveries in real life. Deltadromeus agilis, a new species also found in Morocco, was 25 feet long. It was a fast, fierce and very agile hunter, with a running stride of up to 9 feet. In Argentina, scientists found fossils which may belong to an even larger predator than Carcharodontosaurus. It was named Giganotosaurus carolinni.
