Collision Course of MILKY WAY
AND ANDROMEDA GALAXIES.....Which Destiny for Earth?
Using one of the most powerful computers on the planet, scientists have found
more evidence that our Milky Way galaxy,
with about 400 billion stars including the sun, is on a collision course with a
somewhat larger galaxy, Andromeda. The two galaxies are more than 13
million-trillion miles apart right now, but they are zipping toward each other
at about 310,000 miles per hour. That should put Andromeda on our celestial
doorstep in about 3 billion years, according to John Dubinski, professor of
astronomy at the University of Toronto. The sun and its group of planets,
including the one most dear to our hearts, will face two fates. Either it will
spin completely out of the galaxy, traveling on a long, lonely journey with very
few other stars visible in the sky, or it could plunge into the center of the
new galaxy, the so-called incubator where new stars are formed.
The aftermath of two galaxies merging a per John Dubinski, University of Toronto
will be: Since the sun is expected to burn for about another 5 billion years, if
there’s anyone here to watch they will see it all unfold, although at a very
slow pace. It should all take about a billion years. Stick around for
about 3 billion years, and you should be in for a spectacular show. You can read
more on this by clicking on
ABC NEW.COM....
Learn about your home of MILKY WAY
GALAXY by clicking on the next line.......
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MILKY
WAY, the large, disk-shaped aggregation of stars, or
galaxy,
that includes the
sun and
its
solar system. Its name is derived from its appearance as a faintly luminous
band that stretches across earth’s sky at night. This band is the disk in which
the solar system lies. Its hazy appearance results from the combined light of
stars too far away to be distinguished individually by the unaided eye. The
individual stars that are distinct in the sky are those in the Milky Way galaxy
that lie sufficiently close to the solar system to be discerned separately.
From the middle northern latitudes, the Milky Way is best seen
on clear, moonless, summer nights, when it appears as a luminous, irregular band
circling the sky from the northeastern to the southeastern horizon. It extends
through the constellations Perseus, Cassiopeia, and Cepheus. In the region of
the Northern Cross it divides into two streams: the western stream, which is
bright as it passes through the Northern Cross, fades near Ophiuchus, or the
Serpent Bearer, because of dense dust clouds, and appears again in Scorpio; and
the eastern stream, which grows brighter as it passes southward through Scutum
and Sagittarius. The brightest part of the Milky Way extends from Scutum to
Scorpio, through Sagittarius. The center is in the direction of Sagittarius and
is about 26,000 light-years (= 152,508 trillion year as 1 light year = 5.56
trillion miles) from the sun.
The Milky Way has been determined to be a large spiral galaxy,
with several spiral arms coiling around a central bulge about 10,000 light-years
(58,656 trillion miles) thick. The stars in the central bulge are closer
together than those in the arms, where more interstellar clouds of dust and gas
are found. The diameter of the disk is about 100,000 light-years. It is
surrounded by a larger cloud of hydrogen gas, warped and scalloped at its edges,
and surrounding this in turn is a spheroidal or somewhat flattened halo that
contains many separate, globular clusters of stars mainly lying above or below
the disk. This halo may be more than twice as wide as the disk itself. In
addition, studies of galactic movements suggest that the Milky Way system
contains far more matter than is accounted for by the known disk and attendant
clusters—up to 2000 billion times more mass than the sun contains. Astronomers
have therefore speculated that the known Milky Way system is in turn surrounded
by a much larger corona of undetected matter. Another speculation is that the
Milky Way is a barred spiral galaxy. In April 1997 scientists discovered a
“fountain” of antimatter erupting from the center of the galaxy, raising new
questions about the structure of the Milky Way.
The Milky Way contains both the young, brilliant blue, so-called
type I stars; and the older, giant red, type II stars. The central Milky Way and
the halo are composed of the type II population. Most of this region is obscured
behind dust clouds, which prevent visual observation. Radiation from the central
region has been recorded by use of such special devices as photoelectric cells,
infrared filters, and radio telescopes. Such studies indicate compact objects
near the galactic center, possibly starburst remnants or a massive black hole.
Surrounding the central region is a fairly flat disk comprising
stars of both type II and type I; the brightest members of the latter category
are luminous, blue supergiants. Imbedded in the disk, and emerging from opposite
sides of the central region, are the spiral arms, which contain a majority of
the type I population together with much interstellar dust and gas. One arm
passes in the vicinity of the sun and includes the Great Nebula in Orion.
The Milky Way rotates around an axis joining the galactic poles.
Viewed from the north galactic pole, the rotation of the Milky Way is clockwise,
and the spiral arms trail in the same direction. The period of rotation
decreases with the distance from the center of the galactic system. In the
neighborhood of the solar system the period of rotation is more than 200 million
years. The speed of the solar system due to the galactic rotation is about 270
km/sec (about 170 mi/sec).
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