1.
Three Ways To End Life As We Know It
2008 November 3. Astronomers
hunt for Earth-bound killer rocks. By Charles Burress, San Francisco
Chronicle. Excerpt: ...Giant rocks from space
are hurtling toward us, on track to clobber
our planet. But don't panic. Scientists say
the next killer asteroid - unlike those that
pummeled us in the past - can be deflected if
we know about it far enough in advance.
So while many of us sleep, two Bay Area astronomers
have recently begun standing sentinel against
the cosmic cannonballs that could smash into
Earth. Their big eye is "Nellie," the
36-inch reflecting telescope at the Chabot Space & Science
Center in the Oakland hills.
"We've not discovered anything," said
asteroid-tracker Gerald McKeegan, a member of
the Eastbay Astronomical Society, which is affiliated
with Chabot. "A lot of what we do is follow-up
work."
..."You've got a rock, and now we have
to figure out where that rock is going," said
Chabot staff astronomer Conrad Jung. "We
play a small but important role in trying to
figure it out."
The Chabot center recently became the only Bay Area facility on active duty in the Earth-threatening asteroid search when it was selected to join an official worldwide network of observatories tracking potentially catastrophic "NEOs," - space talk for near Earth objects.
...Chances are small that Earth will be hit
by an asteroid soon, but the consequences would
be so enormous that the U.S. government and
many experts around the world say we must begin
to prepare. NASA's goal is to locate 90 percent
of asteroids that could cause global disasters
- those that come close to Earth's orbit and
are larger than 1 kilometer in diameter - by
the end of this year....
2008 Apr 15. Gauging
a Collider's Odds of Creating a Black Hole.
By DENNIS OVERBYE, NY Times. Excerpt:
... the Large Hadron Collider... starts smashing
protons together this summer at the European
Center for Nuclear Research, or Cern, outside
Geneva, in hopes of grabbing a piece of the
primordial fire, forces and particles that may
have existed a trillionth of a second after
the Big Bang.
Critics have contended that the machine could
produce a black hole that could eat the Earth
or something equally catastrophic.
To most physicists, this fear is more science
fiction than science fact. ...In a paper published
in 2000 with the title "Might a Laboratory
Experiment Destroy Planet Earth?" Francesco
Calogero, a nuclear physicist at the University
of Rome and co-winner of the 1995 Nobel Peace
Prize for his work with the Pugwash conferences
on arms control, deplored a tendency among his
colleagues to promulgate a "leave it to
the experts" attitude. ...society has never
agreed on a standard of what is safe in these
surreal realms when the odds of disaster might
be tiny but the stakes are cosmically high.
In such situations, probability estimates are
often no more than "informed betting odds," said
Martin Rees, a Cambridge University cosmologist,
the astronomer royal and the author of "Our
Final Hour." ...the random nature of
quantum physics means that there is always
a minuscule, but nonzero, chance of anything
occurring, including that the new collider
could spit out man-eating dragons.
...Next year will see the release of the film
version of "Angels and Demons," ...in
which the bad guys use a Cern accelerator
to gather antimatter for a bomb to blow up
the Vatican, and it includes scenes at Cern.
...Neither Dr. Calogero nor Dr. Rees say they
are losing sleep over the collider. Some risk
is acceptable, even inevitable, in the pursuit
of knowledge, they say, and they trust the physicists
who have built it....
2007 September 20. Meteorite
likely caused crater in Peru. By MONTE
HAYES Associated Press Writer. The Associated
Press Excerpt: Peruvian
astronomers said Thursday that evidence shows
a meteorite crashed near Lake Titicaca over
the weekend, leaving an elliptical crater
and magnetic rock fragments in an impact powerful
enough to register on seismic charts….
The Earth is constantly bombarded with objects
from outer space, but most burn up in the
atmosphere and never reach the planet's surface.
Only one in a thousand rocks that that people
claim are meteorites turn out to be real,
according to Jay Melosh, an expert on impact
craters and professor of planetary science
at the University of Arizona….
Such impacts are rare, and astronomists still
want to do other tests to confirm the strike….
Meteorites are actually cold when they hit
Earth, astronomists say, since their outer
layers burn up and fall away before impact…..
More details emerged when astrophysicist Jose
Ishitsuka of Peru's Geophysics Institute reached
the site about 6 miles from Lake Titicaca.
He confirmed that a meteorite caused a crater
42 feet wide and 15 feet deep, the institute's
president, Ronald Woodman, told The Associated
Press on Thursday.
Ishitsuka recovered a 3-inch magnetic fragment
and said it contained iron, a mineral found
in all rocks from space. The impact also registered
a magnitude-1.5 tremor on the institute's
seismic equipment - that's as much as an explosion
of 4.9 tons of dynamite, Woodman said….
Peasants living near the crater said they
had smelled a sulfurous odor for at least
an hour after the meteorite struck and that
it had provoked upset stomachs and headaches….
Meteor expert Ursula Marvin said that if people
were sickened, "it wouldn't be the meteorite
itself, but the dust it raises...."
2007 March 16. The
Sky Is Falling. Really. By RUSSELL L.
SCHWEICKART (a former
Apollo astronaut, is the chairman of the B612
Foundation, which promotes efforts to alter
the orbits of asteroids). Tiburon, Calif.
Americans who read the papers or watch Jay
Leno have been aware for some time now that
there is a slim but real possibility - about
1 in 45,000 - that an 850-foot-long asteroid
called Apophis could strike Earth with catastrophic
consequences on April 13, 2036. What few probably
realize is that there are thousands of other
space objects that could hit us in the next
century that could cause severe damage, if
not total destruction.
2007 January 6. What
Landed in New Jersey? It Came From Outer Space.
By KAREEM FAHIM. Excerpt:
The object that tore through the roof of a
house in the New Jersey suburbs this week
was an iron meteorite, perhaps billions of
years old and maybe ripped from the belly
of an asteroid, experts who examined it said
yesterday. ...it landed - and ruined a second-floor
bathroom - the meteorite is only the second
found in New Jersey, said Jeremy S. Delaney,
a Rutgers University expert who examined it.
...from looking at it, Dr. Delaney and other
experts were able to tell that the object
it had been part of - perhaps an asteroid
- cooled relatively fast. It is magnetic,
and reasonably dense, they determined. The
leading edge - the one that faced forward
as it traveled through the earth's atmosphere
- was much smoother, while the so-called trailing
edge seemed to have caught pieces of molten
metal. ..."The worth of a meteorite like
this is almost completely determined by where
it fell," said Eric Twelker, a geologist
and a dealer in meteorites, who buys and sells
perhaps a hundred of them a month on http://meteoritemarket.com,
his Web site. He was speaking of the premium
placed on meteorites with a compelling back
story, like the football-size rock that crashed
into a parked Chevrolet in Peekskill, N.Y.,
in 1992.
2006 November 14 Ancient
Crash, Epic Wave. By SANDRA BLAKESLEE,
NY Times. Excerpt:
Did catastrophe fall from above in 2807 B.C.?
Mega-tsunamis following meteor impacts left
their mark, researchers say. At the southern
end of Madagascar lie four enormous wedge-shaped
sediment deposits, called chevrons, that are
composed of material from the ocean floor.
Each covers twice the area of Manhattan with
sediment as deep as the Chrysler Building
is high. On close inspection, the chevron
deposits contain deep ocean microfossils that
are fused with a medley of metals typically
formed by cosmic impacts. And all of them
point in the same direction - toward the middle
of the Indian Ocean where a newly discovered
crater, 18 miles in diameter, lies 12,500
feet below the surface. The explanation is
obvious to some scientists. A large asteroid
or comet, the kind that could kill a quarter
of the world's population, smashed into the
Indian Ocean 4,800 years ago, producing a
tsunami at least 600 feet high, about 13 times
as big as the one that inundated Indonesia
nearly two years ago. The wave carried the
huge deposits of sediment to land. Most astronomers
doubt that any large comets or asteroids have
crashed into the Earth in the last 10,000
years. But the self-described "band of
misfits" that make up the two-year-old
Holocene Impact Working Group say that astronomers
simply have not known how or where to look
for evidence of such impacts along the world's
shorelines and in the deep ocean. ...Peter
Bobrowski, a senior research scientist in
natural hazards at the Geological Survey of
Canada, said "chevrons are fantastic
features" but do not prove that megatsunamis
are real. There are other interpretations
for how chevrons are formed, including erosion
and glaciation... It is up to the working
group to prove its claims, he said. ...Bruce
Masse, an environmental archaeologist at the
Los Alamos National Laboratory in New Mexico
...thinks he can say precisely when the comet
fell: on the morning of May 10, 2807 B.C.
Dr. Masse analyzed 175 flood myths from around
the world, and tried to relate them to known
and accurately dated natural events like solar
eclipses and volcanic eruptions. ...14 flood
myths specifically mention a full solar eclipse,
which could have been the one that occurred
in May 2807 B.C. Half the myths talk of a
torrential downpour, Dr. Masse said. A third
talk of a tsunami. Worldwide they describe
hurricane force winds and darkness during
the storm. All of these could come from a
mega-tsunami. Of course, extraordinary claims
require extraordinary proof, Dr. Masse said, "and
we're not there yet."
Weather
Photography has
images of many types of weather/atmospheric
phenomena.
Archive
of Past Articles for Chapter 1
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Chapters
- Three
Ways to End Life
- Astronomers'
Tools
- Cosmic
Engines
- Fathoming
Huge Distances
- Color,
Temperature, and Age
- Dramatic
Change in Stars
- Planet-Star
Systems
- Search
for Habitable Planets
- Cosmos
Begins...and Ends?
Archive
of Past Articles for All Chapters
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9.
Cosmos Begins ... and Ends?
2008 Aug 18. The
Struggle to Measure Cosmic Expansion. By DENNIS
OVERBYE, NY Times. Excerpt:
Hoping to understand why the universe
seems to be coming apart at its seams,
a young astronomer and his colleagues
have embarked on one of the oldest
quests in cosmology, to measure how
fast the universe is growing, how
big it is and how old it is. That
information is encoded in the value
of an elusive number known as the
Hubble constant that has led astronomers
on a merry chase for three-quarters
of a century. "It is the most
fundamental number in cosmology," said
Adam Riess, 38, an astronomer at
the Space Telescope Science Institute
and Johns Hopkins University, and
one of the discoverers 10 years ago
that some kind of "dark energy" is
speeding up the expansion of the
universe.
This spring, in what he called "a
triumph of metrology," Dr. Riess
announced that he and his comrade,
Lucas Macri of Texas A&M University,
had used the Hubble Space Telescope
to make the newest and most precise
measurement yet of this parameter.
Expressed in the quaint terms astronomers
favor, the Hubble constant, Dr. Riess
reported, is 74 kilometers per second
per megaparsec. It means that for
every additional million parsecs
(about 3.26 million light-years)
a galaxy is from us, it is going
74 kilometers per second faster.
... with...an uncertainty of only
4.3 percent.
Only 30 years ago, distinguished
astronomers could not agree within
a factor of two on the value of Hubble's
constant, leaving every other parameter
in cosmology uncertain by at least
the same factor and provoking snickers
from other fields of science.
...Dr. Riess's distance ladder has
only three rungs and one telescope,
leaping from the Milky Way's neighborhood
to supernova explosions as distant
as a billion light-years.
It starts with a galaxy known as
NGC 4258 (a k a Messier 106 in Ursa
Major), where astronomers have found
clouds emitting radio waves at a
frequency characteristic of water
vapor circling the center of the
galaxy, as well as the all-important
Cepheid stars. By tracking the speeds
and motion across the sky of these
clouds with high resolution radio
observations, a team led by James
Herrnstein of the National Radio
Astronomy Observatory in Socorro,
N.M., in 1999 determined its distance
as 23.5 million light-years.
Knowing the distance to that galaxy
allowed Dr. Riess and his team to
calibrate the Cepheids, which they
then used to calibrate supernovas....
2008 May. Underground
Astronomy. By Kathleen M. Wong,
ScienceMatters@Berkeley. Excerpt:
Most scientists who study the cosmos
keep their eyes fastened firmly
on the sky. Not so Bernard Sadoulet.
A Berkeley professor of physics,
Sadoulet is stalking dark matter,
the elusive material that forms
the scaffolding of the universe.
And the place he's laid his traps
is just as shadowy-a former iron
mine more than 2,300 feet underground.
Speculations about dark matter's identity range from the side
effects of additional dimensions to ultralight particles known
as neutrinos. But several lines of thinking have converged on
heavy particles known as WIMPs (weakly interacting massive particles).
"If these particles are the dark matter, they form a dark
halo around the galaxy. We are in this halo, and there are billions
of these particles going through us all the time," Sadoulet
says.
Sadoulet leads an experiment to find these particles within Minnesota's
Soudan Mine. His Cryogenic Dark Matter Search employs detectors
made of silicon or germanium crystals cooled to nearly absolute
zero.
"Within five years, three totally different approaches to
catching WIMPS should be in operation, and we may be at the brink
of a discovery" says Sadoulet. "It's an interesting
time to be searching for dark matter."
2008 Jan 4. NASA
Scientists Identify Smallest Known
Black Hole. NASA Release No.
08-28. Excerpt:
GREENBELT, Md. - Using a new technique,
two NASA scientists have identified
the lightest known black hole.
With a mass only about 3.8 times
greater than our Sun and a diameter
of only 15 miles, the black hole
lies very close to the minimum
size predicted for black holes
that originate from dying stars.
"This black hole is really pushing the limits. For many
years astronomers have wanted to know the smallest possible size
of a black hole, and this little guy is a big step toward answering
that question," says lead author Nikolai Shaposhnikov of
NASA's Goddard Space Flight Center in Greenbelt, Md.
...lowest-mass known black hole belongs to a binary system named
XTE J1650-500...
Archive
of Past Articles for Chapter 9
|
|
Chapters
- Three
Ways to End Life
- Astronomers'
Tools
- Cosmic
Engines
- Fathoming
Huge Distances
- Color,
Temperature, and Age
- Dramatic
Change in Stars
- Planet-Star
Systems
- Search
for Habitable Planets
- Cosmos
Begins...and Ends?
Archive
of Past Articles for All Chapters
|
