SETI public: Fw: S&T's Weekly News Bulletin for April 9

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From: LARRY KLAES (ljk4_at_msn.com)
Date: Mon Apr 12 2004 - 07:34:41 PDT

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----- Original Message -----
From: bulletins_at_SkyandTelescope.com<mailto:bulletins_at_SkyandTelescope.com>
To: ljk4_at_msn.com<mailto:ljk4_at_msn.com>
Sent: Friday, April 09, 2004 8:05 PM
Subject: S&T's Weekly News Bulletin for April 9

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* * * SKY & TELESCOPE's WEEKLY NEWS BULLETIN - April 9, 2004 * * *

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Welcome to S&T's Weekly News Bulletin. Images, the full text of stories
abridged here, and other enhancements are available on our Web site,
SkyandTelescope.com, at the URLs provided below. (If the links don't work,
just manually type the URLs into your Web browser.) Clear skies!

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BUILDING PLANETS IN PLASTIC BAGS

Last year astronaut Donald R. Pettit (NASA/Johnson Space Center) was
aboard the International Space Station preparing his weekly Saturday
Morning Science program, in which he performed various experiments
highlighting the fun things one can do in microgravity. Before him were
plastic bags containing salt, sugar, and coffee grounds. The demonstration
he had planned that morning was fairly mundane -- shake the bags and watch
what happens. Little did Pettit know he might be about to solve
experimentally one of most perplexing paradoxes surrounding the formation
of planets.

For decades theorists have had trouble growing planets starting from small
dust grains in a protoplanetary gas-and-dust disk. Given a turbulent disk
environment with high winds and high-velocity (100 meters/second) impacts
between objects, small, millimeter-size clumps should have difficulty
growing to centimeter size and larger without breaking back into
millimeter fragments. No one had ever seen it work experimentally.

Pettit proceeded to take the bags of particles and shake them in front of
the camera....

> http://SkyandTelescope.com/news/article_1236_1.asp>

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HUBBLE SERVICING: ROBOT TO THE RESCUE?

While astronomers and politicians continue to debate NASA's decision to
cancel further shuttle missions to the Hubble Space Telescope, engineers
are looking for other ways to keep the orbiting observatory alive as long
as possible. Already they're changing how they operate the telescope to
circumvent or delay inevitable hardware failures. And they're looking at
the possibility of dispatching an advanced robot to perform some, if not
all, of the servicing tasks that were originally to be carried out by
space-walking astronauts....

> http://SkyandTelescope.com/news/article_1233_1.asp>

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STAR FORMATION PEAKED LATER THAN THOUGHT

We see lots of stars forming in the universe today, but in fact the most
frenzied action has already occurred. Astronomers agree that the
star-formation rate all across the cosmos peaked many billions of years
ago. But exactly how long ago did this milestone occur, and what was the
maximum birth rate of stars compared to today's? Determining this rate is
critical to understanding how the universe evolved and took on its
present-day character.

A new study by Alan Heavens (University of Edinburgh, Scotland) and three
colleagues finds that starbirth peaked about 5 billion years ago, when gas
clouds were churning out stars at a clip 6 to 8 times faster than now.
Previous studies put the peak 8 billion years ago.

Heavens's team obtained a different result because it used a novel method
for determining the universe's star-formation history....

> http://SkyandTelescope.com/news/article_1235_1.asp>