This is SCIENCE IN THE NEWS in VOA
Special English. I'm Bob Doughty.
And I'm Barbara Klein. On our program this week, we will tell about
the mystery of the aurora borealis, better known as the Northern Lights. We will also tell about an archeological dig
in the southeastern United States. The
project continues to surrender secrets of some very early Americans.
many centuries, people have looked with wonder at the Northern Lights. These mysterious lights often brighten the
night sky in countries near the North Pole.
The Northern Lights are also called the aurora borealis. An aurora is a natural burst of light that
can be seen with the unaided eye. An
aurora over the South Pole is called the aurora australis, or Southern
Auroras appear as large areas of moving
light. They are often green, red or
purple in color. Some auroras can
extend across the sky for thousands of kilometers.
have long known that auroras are caused by a storm of magnetic energy high
above the Earth's surface. But
scientists have been debating exactly what forces in nature cause these storms
to create the colorful light shows.
Recently, researchers working for
the American space agency said they found the answer by using five of the
agency's satellites. The researchers say the sun's and Earth's electromagnetic fields normally move past one
another in different directions. But
when enough energy builds between the two fields, they separate and reconnect
themselves in a new shape.
This reconnection releases a huge amount
of electrical current in the Earth's magnetosphere. The researchers say the
reconnection happens about one hundred twenty-nine thousand kilometers away from the
planet. That is about one third of the
distance to the moon.
five satellites were launched last year as part of the American space agency's
THEMIS project. THEMIS is a
word the agency uses to represent Time History of Events and Macroscale Interactions During
researchers were able to directly observe the magnetic substorms using both the
satellites and twenty ground observatories.
The observatories are in Canada and the American state of Alaska.
four days, the satellites lined up half way between the North and South Poles
to record observations. Equipment on
the ground helped to identify when and where a substorm was forming. Other devices measure the auroral light from
particles moving along Earth's magnetic field.
Their observations of six months ago confirmed that magnetic
reconnection leads to substorms.
The researchers say there is still more
to be discovered about substorms. The Northern Lights are exciting
to watch. However, the forces
responsible for them can damage satellites, guidance systems and radio
communication. They are also a possible
threat to air travelers and astronauts.
Scientists hope that more investigation
will lead to better methods of predicting substorms, both to protect equipment
are listening to the VOA Special English program SCIENCE IN THE NEWS. With Barbara Klein, I'm Bob Doughty.
college student recently found two ancient stone objects in the American state of
South Carolina. He made the discovery
during an archeological dig in an area known as the Topper Site.
The student, Matthew Carey, found the
objects just a short distance from each other.
They appear to have been buried together. University of South Carolina archeologist Albert Goodyear said
the objects could be cutting tools. But
he believes they look like the heads of spears or long knives. Mister Goodyear said they seem to be about
eleven thousand years old.
archeological work at the Topper Site may have uncovered evidence of a
settlement from as early as fifty thousand years ago.
Topper Site got its name from a local man.
Years ago, David Topper told Mister Goodyear about a place he might find
interesting near the Savannah River. A
chemical company owns the land. The
company lets the scientists work on the huge site each spring. The Topper Site covers an area measuring
more than thirty thousand square meters.
begins when the local wild-turkey-hunting season ends. Each May, Albert Goodyear leads volunteers
for five weeks in uncovering the site's mysteries. The volunteers are scientists, teachers, students, and anyone else
who likes to explore the past. They dig
by hand. It is hard, painstaking work. But most scientists would say the site is
well worth the hard work it requires.
Goodyear first began working near the place that would become the Topper Site
in the nineteen eighties. He led a team
searching for objects belonging to the Clovis people. Most scientists at the time believed that these people were the
first settlers in the Americas.
The name "Clovis" came from an area near Clovis, New Mexico. Evidence of the people was found there. Scientists had long believed that human
beings first entered North America across a land bridge from what is now Russia
and Alaska. They thought these first
Americans arrived about eleven or twelve thousand years ago. But in the late twentieth century, some
researchers began to question that theory.
Several discoveries became
especially important in disputing the belief.
Among the most important ones were findings at the Monte Verde Camp in
Chile. Scientists began finding ancient
artifacts there beginning in nineteen seventy-six. The artifacts included a piece of meat that had lasted many
centuries. It might have been from an
ancient animal similar to a modern elephant.
findings at Monte Verde showed that humans were in South America about thirteen
thousand years ago. Experts said that
was about one thousand years before the Clovis people could have traveled
In nineteen ninety-eight, Mister
Goodyear and his team wanted to find more artifacts of the Clovis people. He planned a dig near the Savannah
River. But the river had flooded the
area he wanted to examine. So he
decided to start digging nearby.
Today, he remembers how much he
regretted the flood. He told V.O.A.
that did not want to move his explorations.
But the area proved a big surprise.
The archeologist described it as the best thing that ever happened to
The flood caused Mister Goodyear and his
team to dig about a meter deeper than usual for Clovis artifacts. They found evidence of tools and extremely
small stone particles or flakes. The
objects appeared older than those made or used by the Clovis people. The objects were
found during the last two weeks of the Goodyear team's yearly research project.
Digging at Topper in the following years
added to the artifact collection. The
scientists found artifacts that appear to have come from times before the
years ago, Mister Goodyear and his team found ancient plant material at the
Topper Site. Shortly before the work
was to end, they discovered black soil.
The soil provided charcoal, a material combining wood and other
substances. Charcoal can be tested for
age by a process called radiocarbon dating.
Stafford of the Stafford Research Laboratories in Colorado arrived to take
pieces of the charcoal. Months later,
the test results were announced. They
showed that the charcoal could be up to fifty thousand years old.
If correct, it would mean that the first
settlement in the Americas took place many years earlier than had been
thought. It could also mean settlers
lived in North America fifty thousand years ago.
Some experts do not accept that human
beings made or used the most ancient objects found at the Topper Site. Some believe that the weather and the ages
made these artifacts look like tools.
And experts continue to disagree about when North America was settled.
Goodyear and his team plan to continue digging. They hope to find more evidence of very early peoples in
America. When next May comes, they
will be again excavating at the Topper Site.
This SCIENCE IN THE NEWS program was
written by Jerilyn Watson and Brianna Blake, who also was our producer. I'm Bob Doughty.
Barbara Klein. You can read and
listen to our programs at voaspecialenglish.com. Join us
next week for more news about science in VOA Special English.
Correction: An earlier version of this story incorrectly said that a reconnection between the sun's and Earth's magnetic fields takes place one hundred twenty-nine kilometers from the planet. The correct distance is one hundred twenty-nine thousand kilometers.