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S&T News Bulletin - Feb 17



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         SKY & TELESCOPE'S NEWS BULLETIN -- FEBRUARY 17, 1995
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PLUTO AT 65

February 18th marks an important date in the history of solar-system
observations.  On that day in 1930, a young observing assistant walked
into the director's office at Lowell Observatory and announced, "Dr.
Slipher, I have found your Planet X."  With that, 24-year-old Clyde
Tombaugh made known his discovery of distant Pluto.  The planet's
existence had been predicted by turn-of-the-century astronomers based on
what they thought were perturbations in the motions of Uranus and Neptune.
 But now we know Pluto is too small to have any measurable effect.  What
it *does* have is a satellite, named Charon, which was discovered in 1978.
 That proved very fortunate, for just a few years later the orbit of
Charon and Earth lined up in a way that caused the two objects to pass
repeatedly in front of one another.  Coincidentally, the first of these
"mutual events" was detected exactly 10 years ago, on February 17, 1985. 
But they will not occur again until early in the 22nd century.

Today, Tombaugh still lives with his wife, Patsy, near Las Cruces, New
Mexico.  He still has -- and occasionally uses -- his homemade 9-inch
reflector with which he honed his keen powers of observation.  Tombaugh
turned 89 on February 4th.  And in the 65 years since he discovered Pluto,
the planet has completed only about 1/4 of an orbit around the Sun.

NOVA AQUILAE 1995

The possible nova in Aquila reported last week is the real thing.  Now
about 9th magnitude, the erupting star is at right ascension 19h 05m 27s,
declination -1 deg 42'.  That's about 3 degrees due north of the
3rd-magnitude star Lambda Aquilae.  Spectra of the nova taken within the
last week confirm that it is in the early decline stage, with gas rushing
outward from it at some 1,200 km per second.  Nova Aquilae '95 was
discovered photographically on February 7th by Japanese amateur Kesao
Takamizawa.

A COMET'S CONSEQUENCES

A report in this week's issue of the journal NATURE describes some of the
chemical compounds detected in Jupiter's atmosphere after the impact of
Comet Shoemaker-Levy 9 last summer.  According to French astronomer
Emmanuel Lellouch and his team, the impacts of fragments G and K each
generated 100 million metric tons of carbon monoxide, among other things. 
They believe the CO was not part of the comet or Jupiter, but instead was
synthesized during the heat of each blast.

SPICA OCCULTATION

On February 19th the waning gibbous Moon occults the bright star Spica,
but the event will be visible only from northeast Asia, northern Japan,
Alaska, and Hawaii.  The next Spica occultation observable from the United
States occurs on April 15th.

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   *------------------------------------------------------------*
   | Stuart Goldman         Internet: sgoldman@cfa.harvard.edu  |
   * Associate Editor                 mrastro@aol.com           *
   | Sky & Telescope                                            |
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   | Belmont, MA  02178           Magazine of Astronomy         |
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