Cygnus Arm
Encyclopedia
The Norma Arm is a minor spiral arm of the Milky Way
galaxy extending from and around the central hub region of the Milky Way Galaxy. The inner portion of the Arm is called Norma Arm in narrow meaning. The outer part of it is identified either with Cygnus Arm, which lies outside the Perseus Arm
, or Outer Arm, which is located further away from the center of the Galaxy than Cygnus Arm. Norma Arm has a radius of 15.5 ± 2.8 kpc. It is named for the Norma constellation, through which the Arm as seen from Earth passes.
The Milky Way
Galaxy
in which the Sun
dwells, in common with many other galaxies of similar type, consists of a large mass of star
s drawn by gravitational forces into the form of a relatively flat disc. The disc is rotating, with the dense central body of stars moving at greater speeds than those towards the rim of the disc. As a result, the pattern of stars within the Galaxy as viewed from directly above or below the disc has formed into a spiral.
Because of localised gravitational variations, the spiral pattern has itself formed several distinct 'spiral arms', where particularly large numbers of stars can be found.
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy extending from and around the central hub region of the Milky Way Galaxy. The inner portion of the Arm is called Norma Arm in narrow meaning. The outer part of it is identified either with Cygnus Arm, which lies outside the Perseus Arm
Perseus Arm
The Perseus Arm is one of two major spiral arms of the Milky Way galaxy. The second major arm is called Scutum–Centaurus Arm. Perseus Arm begins from the distal end of the long Milky Way....
, or Outer Arm, which is located further away from the center of the Galaxy than Cygnus Arm. Norma Arm has a radius of 15.5 ± 2.8 kpc. It is named for the Norma constellation, through which the Arm as seen from Earth passes.
The Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
Galaxy
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
in which the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
dwells, in common with many other galaxies of similar type, consists of a large mass of star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
s drawn by gravitational forces into the form of a relatively flat disc. The disc is rotating, with the dense central body of stars moving at greater speeds than those towards the rim of the disc. As a result, the pattern of stars within the Galaxy as viewed from directly above or below the disc has formed into a spiral.
Because of localised gravitational variations, the spiral pattern has itself formed several distinct 'spiral arms', where particularly large numbers of stars can be found.