The Special Ingredients of Earth
 
March 18, 2016:  With its blue skies, puffy white clouds, warm beaches and
abundant life, planet Earth is a pretty special place.  A quick survey of the
solar system reveals . nothing else like it.
 
But how special is Earth, really?
 
One way to find out is to look for other worlds like ours elsewhere in the
galaxy.  Astronomers using NASA's Kepler space telescope and other
observatories have been doing just that.  In recent years they have been
finding other planets increasingly similar to Earth-but still none that appear
as hospitable as our home world.  For those researchers, the search goes on.
 
http://tinyurl.com/hf5g4e6
 
Another group of researchers have taken an entirely different approach.
Instead of looking for Earth-like planets, they have been looking for
Earth-like ingredients.  Consider the following:
 
Our planet is rich in elements such as carbon, oxygen, iron, magnesium,
silicon and sulfur-the stuff of rocks, air, oceans... and life.
 
Are these elements widespread elsewhere in the universe? To find out, a team
of astronomers led by Aurora Simionescu, an astrophysicist at the Japan
Aerospace Exploration Agency (JAXA) in Sagamihara, Japan, used Suzaku, a
Japanese X-ray satellite with NASA participation, to survey a cluster of
galaxies located in the direction of the constellation Virgo.
 
The Virgo cluster is a massive swarm of more than 2000 galaxies, many similar
in appearance to our own Milky Way, located about 54 million light-years
away.  The space between the member galaxies is filled with a diffuse gas so
hot that it glows in X-rays. Instruments onboard Suzaku were able to look at
that gas and determine which elements it is made of.
 
Reporting their findings in the Astrophysical Journal Letters, Simionescu and
her colleagues reported findings of iron, magnesium, silicon and sulfur
throughout the Virgo galaxy cluster.
 
Simionescu says "The elemental ratios are constant throughout the entire
volume of the cluster and roughly consistent with the composition of the sun
and most of the stars in our own galaxy."
 
When the Universe was born in the Big Bang 13.8 billion years ago, elements
heavier than carbon were rare.  These elements are present today mainly
because of supernova explosions.  Massive stars cook elements such as carbon,
oxygen, iron, magnesium, silicon and sulfur in their hot cores and then spew
them far and wide when the stars explode. According to the observations of
Suzaku, the ingredients for making sun-like stars and Earth-like planets have
been scattered far and wide by these explosions.  Indeed, they appear to be
widespread in the cosmos.
 
"The elements so important to life on Earth are available, on average, in
similar relative proportions throughout the bulk of the universe," adds
Simionescu. "In other words, the chemical requirements for life are common."
 
Earth is still special.  But according to Suzaku, there might be other special
places, too.  Suzaku recently completed its highly successful mission.  On
February 17, 2016, JAXA launched a follow-up mission to continue the survey:
Hitomi, previously named ASTRO-H before launch, is a Japanese-led observatory
carrying a key NASA instrument. The observatory will extend such studies to
clusters of galaxies far beyond Virgo.
 
For more news from the distant corners of the cosmos, stay tuned to
science.nasa.gov.
 
 
Regards,
 
Roger

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 * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)