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
A blank Milky Way galaxy map to label by hand. Twelve parts wait for a name: eight on the galaxy seen from above, four on the same galaxy seen from the side.
Read the full guide
Which arm is which, from above
Two wide arms start at the ends of the bar. The one that passes under the center is the Scutum-Centaurus Arm; the one that ends up outside the small rayed dot is the Perseus Arm. Of the two narrow arms, the Sagittarius Arm runs just inside that dot and the Norma Arm ends at the lower left. The rayed dot is the Sun, on a short piece of arm of its own, the Orion Spur.
Four names from the side
The thin lens is the disk and the ball in its middle the central bulge. The wide oval round both is the halo, and the small balls scattered through it are globular clusters. The halo has no line: write its name inside the oval.
Word bank: central bar, central bulge, disk, galactic center, globular clusters, halo, Norma Arm, Orion Spur, Perseus Arm, Sagittarius Arm, Scutum-Centaurus Arm, Sun.
Questions and answers
Why is it called the Milky Way?
Seen from a really dark place, it is a milky band of light across the sky. The English name translates the Latin via lactea, from a Greek phrase meaning milky circle, and the same Greek word is the root of galaxy.
How many stars are in the Milky Way?
It is very difficult to count them from inside the galaxy. NASA Goddard's best estimate is approximately 100 billion stars; other estimates run from 100 to 400 billion.
How long does the Sun take to go around the Milky Way?
About 250 million years for one trip round the center, by NASA Goddard's figure, and the whole solar system goes with it.
What is left off the blank Milky Way galaxy map?
The short arms that lie along the bar, the Outer Arm, and the split of the disk into thin and thick. Sizes in light-years are left off too: the map is not to scale, and the real arms branch more than these plain spirals.