MUSIC: "Our World" theme
Straight ahead on this special edition of "Our World," a look back at 2006 ... Pluto takes a fall ... 25 years of AIDS ... and challenges in international broadcasting ...
ELLIOTT: "A shortwave radio can always pull in signals from far away places, whereas [with] international television you have to have a cooperating satellite system or a cable system that's carrying the channel."
VOA's Kim Elliott, plus TV science guy Mr. Wizard, and more. I'm Art Chimes. Welcome to VOA's science and technology magazine, "Our World."
It's been an interesting year for space exploration. Unmanned craft visiting Mars continued to send back amazingly detailed pictures of the Red Planet. The U.S. announced long-range plans for a permanent base on the Moon. But maybe the biggest space story of the year was the un-discovery of our ninth planet.
In August, the International Astronomical Union, the IAU, stripped Pluto of its status as it agreed on a new definition of a planet.
The IAU vote overturned a committee recommendation that would have left Pluto as a planet. MIT Prof. Richard Binzel, a member of the committee, said expanding knowledge of the far reaches of the solar system made the existing roster of planets inconsistent.
BINZEL: "A new definition was necessary because astronomers are discovering many, many Pluto-like objects out in the outer Solar System, and we simply needed to know what to call them."
Binzel's committee recommended embracing these Pluto-like objects, sometimes called Plutons, as full-fledged planets. That would have included the asteroid Ceres, Pluto's own moon, Charon, and a recently-discovered object that was informally known as Xena, and is now officially called Eris which was hailed at the time as a 10th planet.
But the full IAU membership opted for a narrower definition of a planet, excluding Pluto and those other objects. Astronomer Mike Brown, who discovered Eris, admitted the new classification makes sense.
BROWN: "If you started from scratch, and you looked at the Solar System, if you were flying in from Outer Space, you would very quickly realize that there are eight really large objects in the Solar System, and you would put those into one category and use one word to describe them, whatever your word would be. All of the other objects in the Solar System are much smaller. So it's very clear that from any point of view, the eight planets now are these special objects."
The new definition of a planet is an object that orbits the Sun, is big enough that its gravity has pulled it into a spherical shape, and has swept its orbit clear of other objects.
That last part is what doomed Pluto, which orbits among numerous other bodies known as Trans-Neptunian Objects.
Also, a planet can not be a satellite of another body.
The new planet definition effectively divides Solar System objects into three groups: planets, of which there are now eight; dwarf planets, a group that now includes Pluto; and small Solar System bodies - asteroids and the like.
The terminology is, perhaps, a bit confusing. Dwarf planets, which sound like a subcategory of planets, are actually a completely separate category.
The new planet definition applies only to our Solar System, and doesn't deal with the 200 or so objects known to orbit around distant stars. More of these extra-solar planets, or bodies, or whatever they are, are being discovered all the time.
The AIDS epidemic turned 25 this year. In June 1981, doctors in Los Angeles reported the unusual cases of five otherwise-healthy young homosexual men with pneumocystis carinii pneumonia. It was the first mention in the scientific literature of the disease we now know as AIDS.
Dr. Anthony Fauci has been on the front lines of the battle against HIV/AIDS ever since the beginning. He now heads the National Institute of Allergy and Infectious Diseases, part of the U.S. National Institutes of Health.
In a visit to VOA in July he recalled reading the first reports and went on to recap the status of the AIDS epidemic.
FAUCI: "I was sitting in my office at the NIH up in Bethesda [MD], and from that moment I can tell you historically, although I had a very, very troubled feeling when I saw that, because I knew this was something that was not a fluke, this was something very unusual, I didn't know what it was.