archiv~1.txt: SETI S&T's News Bulletin for March 19, 1999

SETI S&T's News Bulletin for March 19, 1999

Larry Klaes ( lklaes@bbn.com )
Mon, 22 Mar 1999 08:36:10 -0500

>From: stargate@gte.net
>Date: Sat, 20 Mar 1999 22:24:25 -0600 (CST)
>to: lklaes@bbn.com
>subject: S&T's News Bulletin for March 19, 1999
>
>SKY & TELESCOPE'S NEWS BULLETIN
>
>MARCH 19, 1999
>
>MORE MARTIAN MICROBES?
>
>On Thursday, March 18th, NASA scientists offered new evidence that
>fossilized microbes could be present in at least three meteorites from
>Mars. Kathie L. Thomas-Keprta (NASA/Johnson) showed that the controversial
>stone known as Allan Hills 84001 contains many microscopic crystals of the
>iron-rich mineral magnetite. One-fourth of these are perfectly shaped,
>same-sized hexagonal prisms free of chemical impurities. Certain bacteria
>routinely produce such ultrapure magnetite crystals as a means of orienting
>themselves to Earth's magnetic field, and they cannot be formed by any
>known inorganic process. Of all the hints of microbial fossils seen in ALH
>84001, Thomas-Keprta says the magnetite grains provide the strongest
>evidence.
>
>David S. McKay (NASA/Johnson) raised the possibility that two other Martian
>meteorites, Nakhla and Shergotty, contain fossilized microbes. His
>scanning-electron-microscope views show a variety of round and oval forms
>found in tiny cracks within a Nakhla stone. "Are they microfossils?" McKay
>asked aloud. "We don't know." But he noted that the blobs are enriched in
>iron oxides, a common occurrence when a microbe dies and its cell becomes
>mineralized. Moreover, the suspect features are a few tenths of a micron
>across, comparable in size to many bacteria. (Many of the putative fossils
>in ALH 84001 were much smaller -- too tiny, microbiologists argue, to have
>been viable lifeforms.) The NASA team will attempt to examine the blobs'
>interiors for hints of cellular structure and to determine whether they
>resulted from terrestrial contamination. Unlike ALH 84001, which sat on the
>ice fields of Antarctica 16,000 years before its discovery, many pieces of
>Nakhla were recovered almost immediately after falling in Egypt on June 28,
>1911. McKay's sample came from a fragment with an intact "fusion crust"
>that was opened in sterile, clean-room conditions last year.
>
>McKay also showed suspicious features from the interior of Shergotty,
>though the study of those is just getting under way. Shergotty crystallized
>from molten rock a mere 165 million years ago, whereas Nakhla is about 1.3
>billion years old and ALH 84001 is 4 billion years old. Thus, if microbial
>fossils really exist in all three of these meteorites, it means that life
>has existed on Mars throughout much of the planet's history and could be
>there today. NASA hopes to obtain samples of the red planet via spacecraft
>as early as 2008, and the agency is currently wrestling with how best to
>isolate and study the Martian material once it reaches Earth.
>
>Thomas-Keprta and McKay reported their results at the 30th annual Lunar and
>Planetary Science Conference in Houston, Texas, which this year drew nearly
>1,100 researchers -- a record attendance -- from around the world.
>
>WHENCE CAME THE MOON?
>
>Other results presented at the conference include evidence that the Moon
>did indeed form from the remnants of a collision between the Earth and a
>Mars-size body early in the history of the solar system. New support for
>this scenario comes from data collected by NASA's Lunar Prospector
>spacecraft. Analysis by Alex Konopliv (Jet Propulsion Laboratory) of
>gravity measurements reveal that the Moon has a small metal-rich core,
>amounting to only 4 percent of the body's total mass (Earth's core is 30
>percent of the planet). If the Earth and Moon had coalesced from the gas
>and dust of the solar nebula at the same time, they should have similar
>compositions and core sizes. However, a large object's grazing collision
>with the proto-Earth would have blasted some of the iron-poor outer layers
>into space. Much of it would have remained in Earth orbit and then amassed
>into our satellite.
>
>HUBBLE EXAMINES GALAXIES IN INFRARED
>
>Pictures released Thursday by the Space Telescope Science Institute reveal
>where stars are being born in spiral galaxies. The images are part of a
>survey of about 100 spirals. The dust-penetrating gaze of Hubble's Near
>Infrared Camera and Multi-Object Spectrometer (NICMOS) highlighted knots of
>glowing hydrogen in the galaxies' arms, where the stellar raw material is
>being irradiated by ultraviolet light from massive newborn stars. The
>reddish knots seen in the cores of some galaxies (such as NGC 2903) could
>be from star birth or from the radiation generated by an active nucleus,
>perhaps powered by a massive black hole.
>
>DAYTIME ALDEBARAN OCCULTATION
>
>The Moon occults (covers) Aldebaran during daytime for eastern and central
>North America on March 22nd. If the sky is clear, you should be able to
>watch this event with a telescope. See the timetable in the January Sky &
>Telescope, page 115, or at
>http://www.skypub.com/sights/occultations/lunar/lunarchart.html (the times
>and dates in the table are in Universal Time).
>
>EQUINOX UPON US
>
>The Sun arrives at the March equinox at 8:46 p.m. EST on Saturday, March
>20th, crossing the equator heading north. This is the moment when spring
>begins in the Northern Hemisphere and fall begins in the Southern
>Hemisphere.
>
>
>THIS WEEK'S "SKY AT A GLANCE"
>
> Some daily events in the changing sky, from the editors of SKY &
>TELESCOPE.
>
>MARCH 21 -- SUNDAY
>
> * The crescent Moon shines high in the west this evening, far to the
>upper left of Venus and Saturn. Higher to the Moon's upper left is orange
>Aldebaran. To the Moon's right or upper right are the Pleiades.
>
>MARCH 22 -- MONDAY
>
> * The Moon occults (covers) Aldebaran during daytime for eastern and
>central North America. If the sky is clear, you should be able to watch
>this event with a telescope. See the timetable in the January Sky &
>Telescope, page 115, or at
>http://www.skypub.com/sights/occultations/lunar/lunarchart.html (the times
>and dates in the table are in Universal Time).
>
> * Early Tuesday morning the faint asteroid 120 Lachesis will occult a
>10th-magnitude star in Libra for up to 39 seconds for observers along a
>wide path from central Canada to the Southwest. The occultation should
>happen within a few minutes of 7:57 Universal Time March 23rd in Winnipeg
>and 8:04 UT in Arizona. See the finder chart in the March Sky & Telescope,
>page 106, or in the occultation section of Sky & Telescope's Web site,
>http://www.skypub.com/sights/occultations/occultations.html#menu (where
>late news and prediction updates may also be posted).
>
>MARCH 23 -- TUESDAY
>
> * The Moon shines high to the upper right of Orion in tonight's evening
>sky.
>
>MARCH 24 -- WEDNESDAY
>
> * First-quarter Moon (exact at 5:18 a.m. Eastern Standard Time).
>
>MARCH 25 -- THURSDAY
>
> * The red long-period variable star R Leporis, "Hind's Crimson Star"
>below Orion, should be at maximum brightness (7th magnitude) around this
>date.
>
>MARCH 26 -- FRIDAY
>
> * Saturn's largest moon, Titan, can be found four ring-lengths to
>Saturn's west this evening through Sunday evening. A small telescope will
>show it.
>
>MARCH 27 -- SATURDAY
>
> * Regulus is lower left of the Moon early this evening, and directly left
>of it later in the evening.
>
>
> ============================
> THIS WEEK'S PLANET ROUNDUP
> ============================
>
>MERCURY is hidden low in the glow of sunrise.
>
>VENUS is the bright "Evening Star" in the west during and after dusk. Much
>fainter Saturn appears to its lower left early in the week, and farther
>below it later in the week.
>
>MARS rises around 9 or 9:30 p.m. It's well up in the southeast by
>midnight, shining brightly in western Libra at magnitude -0.8. In a
>telescope Mars is 13 arcseconds in apparent diameter. It will reach
>opposition on April 24th and pass closest to Earth on May 1st, when it will
>appear 16.2 arcseconds wide.
>
>JUPITER is hidden low in the glow of sunset.
>
>SATURN shines to the lower left of bright Venus early this week, and
>farther below it later in the week.
>
>URANUS and NEPTUNE are just emerging from the glare of sunrise.
>
>PLUTO, magnitude 13.8, is in Ophiuchus in the south before dawn. See the
>finder chart in the March Sky & Telescope, page 103.
>
>(All descriptions that relate to the horizon or zenith are written for the
>world's midnorthern latitudes. Descriptions that also depend on longitude
>are for North America. Eastern Standard Time, EST, equals Universal Time
>minus 5 hours.)
>
>More details, sky maps, and news of other celestial events appear each
>month in SKY & TELESCOPE, the essential magazine of astronomy. See our
>enormous Web site at www.skypub.com. Clear skies!
>
>SKY & TELESCOPE, P.O. Box 9111, Belmont, MA 02478 * 617-864-7360 (voice)
>
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>
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