The Messier 55 globular cluster is shown in a freshly published picture by
NASA's Hubble Space Telescope, which is ablaze with stars.
A stunning new picture from NASA's Hubble Space Telescope shows an old star
cluster in the distance.
Only a small portion of Messier 55 (M55), a globular cluster in the
constellation Sagittarius (The Archer) that is home to about 100,000 stars,
is visible in the stunning Hubble image. According to astronomers, some of
these stars, particularly in the middle of M55, twinkle with varying
luminosity.
M55's star cluster has a spherical form thanks to the gravitational force
of its many stars, which is a characteristic shared by more than 150 other
spherical objects in the Milky Way galaxy.
M55's star cluster has a spherical form thanks to the gravitational force
of its many stars, which is a characteristic shared by more than 150 other
spherical objects in the Milky Way galaxy.
About 17,000 light-years away from Earth, the enigmatic M55 is a mystery to
astronomers. The cluster has a circumference of 100 light-years and, as seen
from Earth, is roughly two-thirds the breadth of a full moon. Although M55
is reasonably bright, the atmosphere of the Earth makes it difficult for
viewers in the Northern Hemisphere to see the cluster's stars.
Messier 55 is big and brilliant, but it lacks a dense center, and many of
its stars are quite faint, making it difficult to view in less-than-ideal
circumstances, according to NASA officials in a
picture description released on Friday (March 17).
M55 was
found
in 1752 by French astronomer Nicolas Louis de Lacaille, who observed that
the cluster "resembles an indistinct nucleus of a large comet." Charles
Messier, a French scientist and the creator of the renowned Messier
collection of 110 deep-sky objects, one of which is M55, soon began the
search.
When Messier eventually located the cluster in 1778 from his telescope in
Paris, it had taken him 26 years. He
characterized
it as "a nebula which is a whitish spot, of about 6′ extent, its light is
even, and does not appear to contain any star."
However, the Hubble Space Telescope doesn't experience any of the
difficulties those Earth-based viewers experienced. The telescope can
capture the best views of M55 from its orbit above the Earth's atmosphere
and can even discern its individual stars.
At least 93 of the 110 Messier objects have been captured in stunning
images by the observatory, which was put into orbit around the Earth in 1990
and is still operating today.
