Galactic centerThe middle of the galaxy. A supermassive black hole, Sagittarius A*, lies here.
Central barA thick bar of stars across the center. The two major arms start at its ends.
Arms and the Sun 6
Scutum-Centaurus ArmOne of the two major arms. It starts at an end of the bar.
Perseus ArmThe other major arm. It passes outside the Sun’s place.
Sagittarius ArmA minor arm, just inside the Sun’s place.
Norma ArmA minor arm, filled mostly with gas and pockets of new stars.
Orion SpurA small, partial arm between the Sagittarius and Perseus arms.
SunOur solar system, about halfway out from the center.
Seen from the side 4
DiskThe flat part of the galaxy, which holds the spiral arms.
Central bulgeA tight concentration of stars round the center.
HaloA wide cloud of old stars, star clusters and dark matter.
Globular clustersTight balls of old stars that orbit in the halo.
How this list was compiled: Every name checked on 2026-10-01 in at least two of these. (1) NASA Science: The Milky Way Galaxy, https://science.nasa.gov/resource/the-milky-way-galaxy/ (two major arms, Scutum-Centaurus and Perseus, attached to the ends of a thick central bar; the minor Norma and Sagittarius arms; the Sun near the Orion Arm or Orion Spur, between the Sagittarius and Perseus arms); Galaxy Types, https://science.nasa.gov/universe/galaxies/types/ (the disk, the central bulge, halos of old stars, star clusters and dark matter; barred spirals); Galaxies, https://science.nasa.gov/universe/galaxies/ (a disk more than 100,000 light-years across; the Sun about halfway from the center). (2) NASA Goddard, Imagine the Universe, The Milky Way Galaxy, https://imagine.gsfc.nasa.gov/science/objects/milkyway1.html (a barred spiral; the Sun about 25,000 light-years from the center; how the shape is known from inside). (3) Wikipedia, Milky Way, https://en.wikipedia.org/wiki/Milky_Way (Galactic Center and Sagittarius A*; the bar; the arms and the Orion Arm; a halo of old stars and globular clusters). Licence: own work
The drawing: Drawn for this site on 2026-10-01 from plain geometry. Own original drawing; nothing is traced or copied, and no agency image was used. Licence: own work
How it works
Label the parts of the Milky Way galaxy on two drawings: face-on, with the bar, the spiral arms and the Sun's place, and edge-on, with the disk, the bulge and the halo. Neither is to scale.
Read the full guide
Face-on: the bar and the arms
The Milky Way: a barred spiral. NASA's map shows two major arms, Scutum-Centaurus and Perseus, starting at the ends of the central bar, with the minor Norma and Sagittarius arms between them. The Sun lies on the Orion Spur, between the Sagittarius and Perseus arms, about halfway out from the center.
Edge-on: disk, bulge and halo
From the side the galaxy is a thin disk with a bulge of stars in the middle. Round both lies the halo: old stars, globular clusters and dark matter. Nobody has seen the galaxy from outside, so the arms are a best map, drawn here as simple spirals.
Orion Arm and Local Arm count as answers for the Orion Spur.
Questions and answers
What are the main parts of the Milky Way galaxy?
A central bulge with a bar of stars across it, a flat disk that holds the spiral arms, and a halo of old stars and globular clusters around them. A supermassive black hole, Sagittarius A*, lies at the center.
Where is the Sun in the Milky Way?
On the Orion Spur, a small partial arm between the Sagittarius and Perseus arms. NASA puts the solar system about 25,000 light-years from the center, roughly halfway out.
How many spiral arms does the Milky Way have?
It depends on the survey. One NASA map shows two major arms, Scutum-Centaurus and Perseus, and two minor ones, Norma and Sagittarius. Maps of young stars and gas clouds show four arms. The structure is still being worked out.
How do we know the shape if we cannot see it from outside?
From clues inside it. The band of stars across the night sky shows that the galaxy is flat, and maps of young, hot stars and gas clouds trace the arms, as they do in other spiral galaxies.