[Prev][Next][Index]

S&T News Bulletin - Apr 28

======================================================================
         SKY & TELESCOPE'S NEWS BULLETIN -- APRIL 28, 1995
======================================================================

SOUTHERN ANNULAR ECLIPSE

The Sun undergoes an annular eclipse on April 29th, visible from a track
that crosses South America from northern Peru to northern Brazil.  Like
last May's widely observed event, about 94 percent of the Sun's diameter
will be covered by the Moon at eclipse maximum, which occurs at 17:32
Universal Time.  However, little of this is visible from the U.S.  Only
Floridians will see a partial eclipse, which peaks at 2:07 p.m. EDT with
12% of the Sun's diameter covered.  See page 73 of April's SKY & TELESCOPE
for more details.

MERCURY AT DUSK

As May opens, Mercury is in the midst of its best apparition of the year.
The illusive planet can be spotted just to the left or lower left of the
Pleiades in the west-northwest after sunset, and on May 1st a slender
crescent Moon joins the grouping.

GAMMA RAYS AND SPF300

As if we don't have enough to worry about, a Princeton astronomer has
posed a new long-term threat to life on Earth.  Stephen E. Thorsett
suggests that distant collisions of co-orbiting neutron stars might
explain the enigmatic gamma-ray bursts that astronomers have been
observing for decades.  But some of these binary systems are much closer,
and one (PSR B1534 +12) is only 1,600 light-years away.  According to
Thorsett, if that binary collided, the resulting gamma-ray burst would
shower the Earth with the energy equivalent to 10,000 megatons of TNT.
This would produce enough nitric oxide and other compounds in the
atmosphere to destroy all of the planet's ozone, leaving the surface
without protection from solar ultraviolet radiation for years.  The gamma
rays would also create nitric acid, giving the world a few really bad
years of acid rain. But there's no need to stockpile the suntan lotion
just yet -- Thorsett estimates that a gamma-ray burst within 3,200
light-years of Earth may happen every 100 million years or so.

NEW SUPERLUMINAL SOURCE

Last year radio astronomers found the first object within the Milky Way
appearing to show faster-than-light motion.  Now a second such object has
been reported at radio, optical, and X-ray wavelengths.  Located some
10,000 light-years away in the direction of Scorpius, the source has
components with the unprecedented proper motion of 1 arc second every
three weeks.  The pieces appear to be flying apart faster than the speed
of light, but this is really just an illusion created by matter traveling
at relativistic speeds.  Because this source is so close and has an
optical counterpart, astrophysicists are excited about what might be
learned about the violent activity that must be taking place in such
exotic objects.

WEB SURFING THE CBAT

For those who hope to discover a comet or nova sometime soon, the
International Astronomical Union's Central Bureau for Astronomical
Telegrams (CBAT) has inaugurated a homepage on the World Wide Web.  The
site gives information about the services offered by the Bureaus, and
those who subscribe to its computer service can use it to access the CBAT
computers via telnet. The URL is
http://cfa-www.harvard.edu/cfa/ps/cbat.html.

HUBBLE ANNIVERSARY

Monday, April 24th, marked the fifth anniversary of the launch of the
Hubble Space Telescope.  It's been a struggle at times, but the orbiting
observatory now appears to be fulfilling its mission objectives
exceedingly well.

=======================================================================
The News Bulletin is provided as a service to the amateur-astronomer
community by SKY & TELESCOPE magazine.  Electronic distribution of the
News Bulletin is encouraged; however, this text may not be published
without permission of Sky Publishing Corp. At the present time, the News
Bulletin is not available via electronic mailing list.
=======================================================================
For subscription info to SKY & TELESCOPE, email: skypub@cfa.harvard.edu
=======================================================================

   *------------------------------------------------------------*
   | Stuart Goldman         Internet: sgoldman@cfa.harvard.edu  |
   * Associate Editor                 mrastro@aol.com           *
   | Sky & Telescope                                            |
   * P. O. Box 9111           Sky & Telescope: The Essential    *
   | Belmont, MA  02178           Magazine of Astronomy         |
   *------------------------------------------------------------*