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1.VOA常速
【NASA to Launch Black Hole Hunter】
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TEXT:The U.S. space agency is set to launch a telescope into space June 13 to seek out and study black holes -- those still-mysterious celestial bodies that scientists believe lie at the heart of every massive galaxy, including our own Milky Way.
Black holes have a gravitational pull so intense that not even light can escape from them. As gas, dust and stars are sucked in, the material accelerates and heats up, generating powerful X-ray light emissions.
Only a few decades ago, scientists thought black holes were rare. But their thinking has changed in the past 20 years, and now NASA is setting out to conduct a census of the black holes in the universe.
The U.S. space agency is launching a black hole hunter, a new telescope called NuSTAR, but formally known as Nuclear Spectroscopic Telescope Array.
Paul Hertz is the director of NASA's astrophysics division.
"Stars, nebulae and black holes emit X-rays of the type that we use in medical X-rays, and these cannot be detected from the surface of the Earth," explained Hertz. "But the NuSTAR telescope will focus these X-rays onto its digital camera and send the pictures back to Earth for scientific analysis."
Current telescopes provide images that show a general glow from hundreds of massive black holes. NASA expects NuSTAR will be able to provide far better images of black holes and other high-energy events when it surveys the extra-galactic sky.
The images will be studied by people around the world, including NuSTAR's principal investigator, Fiona Harrison.
"NuSTAR will open a whole new window on the universe, by being the very first telescope to focus on high-energy X-rays. As such, it will make images that are 10 times crisper and 100 times more sensitive than any telescope that is operated in this region of the spectrum," Harrison said.
The NuSTAR telescope is about the size of a refrigerator, but it has a hidden tool. About a week after NuSTAR launches, it will deploy a 10-meter mast that will separate its mirrors from its detectors. That mast provides the distance required to focus the X-ray light into sharp images.
NASA scientists say that perhaps two out of every three black holes in the universe are hidden.
This telescope will be able to find these black holes behind their obscuring veils of dust and gas. It will also be able to tell how quickly a black hole is spinning, which will help scientists learn how black holes form.
"Like all of our NASA missions, we're going to find unexpected things out there that will lead us to questions and answers that we aren't even anticipating at this time," predicted NASA's Paul Hertz.
NASA says NuSTAR will start providing data to scientists about a month after its launch.
2.VOA慢速
【A Blog Where Foreign Students Can Get Answers】
TEXT:This is the VOA Special English Education Report.
International students have a lot of questions about studying in the United States. But what do you suppose is the most common question?
We asked an expert right here in our building. Jessica Stahl is editor of VOA's Student Union blog. Jess blogs for international students interested in American higher education.
JESSICA STAHL: "I think the number one question that I get is financial aid and scholarships. People always want to know, 'How do I get money?' I think that's everyone's biggest concern.? Unfortunately, of all the questions I get, that's the one with the most complicated answer."
The short answer is this: Financial aid programs are often just for American students. But programs for international students do exist. You just have to look for them.
Jess says probably the next most often asked question is about language skills.
JESSICA STAHL: "'How do I improve my English, TOEFL level?' Because they have to take the TOEFL exam to apply to colleges, so [there is] a lot of concern about getting up to the level they need on that exam."
Of course, one way many students improve their English is with Special English, like this program. But we like the Student Union's Glossary of Confusing Words used in education. Readers can send in suggestions.
One newly added word is "catalog."
"A university catalog (or college catalog) is an official publication that contains all the information a current or prospective student might need about academics and student services at a university."
Jess has eighteen foreign student bloggers at American schools. Even they were unsure what a catalog is. The students share their experiences studying in the United States -- for example, how they feel when they face cultural stereotypes. Simba, from Zimbabwe, recently wrote about going to lunch with a group of American students. Simba said he felt hurt when one of them was surprised to learn that Facebook is available in Zimbabwe.
Jess says the Student Union and its Facebook page get a lot of comments.
JESSICA STAHL: "I hear from a lot of Chinese students, a lot of Pakistani students -- one of our big audiences -- Nigeria, Indonesia. Pretty much all over the world."
Jess gave us a list of websites where you can research colleges and universities, financial aid and much more. We'll post the list at 51voa.com. She says the only "must-know" site for all international students is EducationUSA, from the State Department. The address is educationusa.info. And if you only know one other site it should be Study in the States, from the Department of Homeland Security. That address is studyinthestates.dhs.gov.
And that's the VOA Special English Education Report, written by Jerilyn Watson. I'm Bob Doughty.
