This is Science in the News, in VOA Special English. I'm Bob Doughty.
And I'm Sarah Long. This week: meet Sedna the planetoid.
Learn how satellites may give early warning of disease outbreaks.
Also, a study of sexually transmitted diseases in young Americans.
And a report on World TB Day, all coming up.
|Artist's version of Sedna.
(Image - NASA/JPL-Caltech/R. Hurt)
The red object is thirteen-thousand-million kilometers from Earth. But it will get ten times farther. It is the most distant object known to orbit the sun. The discovery means that the solar system is bigger than scientists thought.
NASA, the American space agency, helped pay for the research. Michael Brown of the California Institute of Technology, Caltech, in Pasadena led the team. Chad Trujillo of Gemini Observatory in Hilo, Hawaii, also took part. So did David Rabinowitz of Yale University in New Haven, Connecticut.
|Arrow points to Sedna in this discovery photo taken from the Palomar Observatory. The planetoid is three times farther from Earth than Pluto is.
(Photo - NASA/Caltech)
But Sedna the planetoid is in a much colder place. The scientists estimate the surface temperature at about two-hundred-forty degrees below zero Celsius. When Sedna is even farther from the sun, the temperature drops close to what scientists call absolute zero. This is minus two-hundred-seventy-three degrees Celsius. In theory, this is as cold as cold can get.
So why is Sedna called a planetoid, and not our tenth planet? Mostly because of its size. The scientists measure Sedna at about one-thousand-seven-hundred kilometers around. This is about twenty-five percent smaller than the smallest planet, Pluto.
Sedna also has an unusual orbit. The shape is much more elliptical than the orbits of most of the planets. Picture a circle stretched far from two opposite points.
So how far away does Sedna get? Consider it this way: Sedna takes more than ten-thousand years to travel around the sun. Earth takes one year.
Michael Brown at Caltech says the planetoid is evidence of what scientists call the Oort Cloud. This is an area of comets that orbit the sun, at least in theory. But others think Sedna is more likely part of the Kuiper Belt. This is an area of asteroids and other objects in orbit.
Either way, the scientists all seem to agree that Sedna may tell much about the history of our solar system.
Here on Earth, NASA scientists think satellites can tell when and where diseases might appear. The idea is to look for environmental conditions that increase populations of insects like mosquitoes that spread malaria.
VOICE ONE (CONT):
Ronald Welch works at the NASA Global Hydrology and Climate Center in Huntsville, Alabama. Mister Welch says scientists and health workers are now visiting places where diseases have already appeared. They are also studying satellite images to see how these areas look from space.
NASA says a Russian scientist, E.N. Pavlovsky, first expressed such an idea in the nineteen-sixties.
Ronald Welch is working with health officials in India to develop an early warning system. They are working in an area of more than four-hundred villages south of New Delhi. Mister Welch says the hope in the near future is to provide about a one-month warning before a malaria outbreak.
Mosquitoes lay their eggs in water. Satellites would find an area with a lot of rainwater on the ground. Scientists also know that temperatures must be at least eighteen-degrees Celsius for the disease to survive in the mosquitoes. When conditions seem right for malaria to appear, workers would go to the area. They would spray chemicals to kill the young mosquitoes before they leave the water.
This is Science in the News, in VOA Special English.
Wednesday, March twenty-fourth, is World TB Day. TB is the lung disease tuberculosis. India will lead the observance this year with public health events. Health experts say a new person is infected with TB somewhere in the world every second. Then they spread the bacteria through the air when they cough or sneeze.
The problem is even more serious among refugees. The World Health Organization says half of all refugees may be infected with TB. Refugees often live in crowded conditions and do not have enough food or health care.
Many people leave refugee camps to look for work or family members, or to return home. If they start treatment in the camp, but discontinue it when they leave, the infection may stay in their bodies. Then the disease becomes harder to cure, and easier to spread.
Medicine can take six to eight months to cure TB. But doctors say a person who takes the medicine stops infecting other people in about two weeks.
The World Health Organization says refugees with TB should take a combination of four medicines for at least two to three months. Then they are close to being cured and will not spread the infection.
Tuberculosis in children may affect any part of the body. Children should be examined for TB if they are sick for more than ten days. Weight loss and a lack of energy are two possible signs. Children should also be examined if they live close to someone with TB.
Experts say mothers who are infected with TB should continue to breastfeed their babies. Mother's milk helps protect babies against disease. Babies may die from other diseases if they stop nursing.
Also, health workers urge people to cover their mouth when they cough. And people should not discontinue their medicine when they begin to feel better. They must continue to take the medicine to kill all the germs.
Now we talk about another way diseases are spread.
Researchers have just published a study of sexually transmitted diseases in the United States in two-thousand. They say there were nineteen-million new cases that year. Almost half were in people between the ages of fifteen and twenty-four. Yet people in this age group represent only twenty-five percent of what the researchers call the sexually experienced population.
Researchers from the Centers for Disease Control and Prevention wrote two reports. Both appear in Perspectives in Sexual and Reproductive Health, published by the Alan Guttmacher Institute.
Sharon Camp heads this non-profit group in New York. She says most young people are sexually active. However, she says many are poorly equipped to prevent infections or to seek testing and treatment.
The researchers say nine-million infections were reported in young people in two-thousand. They estimate the cost to treat these people over their lifetimes could reach more than six-thousand-million dollars. Most of the cost is connected to the treatment of H.I.V., the virus that causes AIDS.
But AIDS is not the only threat from sexually transmitted diseases. Three other diseases represent almost ninety percent of all new cases among people in the United States age fifteen to twenty-four.
One is the human papillomavirus. H.P.V is usually harmless and goes away. But some forms can cause cervical cancer and other conditions. The two other diseases are trichomoniasis and chlamydia. Doctors treat these with antibiotics. Yet many people never know they have a sexually transmitted disease, unless they go for a test.
Health experts and a group of young people prepared a separate report released by the University of North Carolina.
It says programs that only teach young people not to have sex until marriage will not control the spread of disease. In January, President Bush proposed a one-hundred-percent increase in federal money for programs that teach abstinence.
The report says young people need to learn about abstinence. But it says they also need realistic advice about other ways to prevent infection.
SCIENCE IN THE NEWS was written by Caty Weaver, Paul Thompson, Karen Leggett and Cynthia Kirk, who was also our producer. I'm Sarah Long.
And I'm Bob Doughty. Join us next week for more news about science, in Special English, on the Voice of America.