SPACE
& SCIENCE NEWS: February 2003
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& science news > space & science news: February 2003
Probing the heart of darkness
(Feb 19, 2003)
For the first time, astronomers have tracked an individual star in
orbit around the supermassive black hole that lies at the center of
our galaxy and whose location is indicated in the photo. The star
in question, known as S0-2, is 15 times as massive as the Sun, appears
to be about 10 million years old, and is orbiting the central black
hole at a distance of a mere 68 AU (just over 10 billion km - a bit
more than the Earth-Pluto distance) and an astonishing speed of 9,000
km per second. The research team, led by UCLA's Andrea Ghez, used
the Keck Observatory
on Hawaii to obtain unprecedented views of the region of space around
Sgr A*. Their data provide the best estimate yet of the mass of the
black hole and the extent of its event horizon – the surface
from within which nothing can escape back into the outside universe.
The mass comes out to three million solar masses – give or take
half a million – and the event horizon must be considerably
less than 68 AU. But as one puzzle is solved, another emerges. How
can a star as big as S0-2 have formed so close to such a gravitational
monster? Only more observations will tell.
For more, go here
(BBC). |
Mars: water, water, everywhere ...
(Feb 17, 2003)
The latest findings from the Mars Odyssey spacecraft currently in
orbit around the Red Planet suggest that there's enough water ice
on Mars, if melted, to inundate the entire planet to a depth of at
least 13 cm (5 inches) – and that includes only the ice found
within the top couple of meters of soil. This is extraordinarly good
news both for the prospects of indigenous life, either extinct or
extant, and those for future manned Mars missions. Effectively, every
kilogram of Martian soil would yield half a kilo of water if it were
baked in an oven by visiting astronauts. Localized natural melting
would also provide one of the basic requirements for microbial life.
And there are strong signs, notably in the form of gullies on the
sides of some craters and ravines (such as those shown here) that,
on occasions, water still runs across the surface of the planet.
For more on this, visit the Mars
Odyssey homepage, this
article at spacref.com, or my own encyclopedia entries, including
Mars, life
on Mars, Martian
vegetation. For more, go here
(BBC). |
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