Milky Way - Constellations

Along its way in the sky, the Milky Way touches the large number of 38 constellations, i.e. the Milky Way band of increased star density covers at least parts of these constellations; the 27 in boldface are crossed by the Galactic Equator:

And, Aql, Ara, Aur, Cam, CMa, CMi, Car, Cas, Cen, Cep, Cir, CrA, Cru, Cyg, Del, Gem, Her, Lac, Lup, Lyr, Mon, Mus, Nor, Ori, Oph, Per, Pup, Pyx, Sge, Sgr, Sco, Sct, SerCd, Tau, TrA, Vel, Vul.

It is exceptional at first glance that one great circle like the Galactic Equator crosses so many constellations (compare e.g. the zodiac which touches only 14 and crosses 13 constellations), but less peculiar when considering that the density of bright stars is much higher in low galactic latitudes, i.e. near the galactic equator, and that bright stars were always used to define constellations.

The constellations along the Galactic Equator are as follows, with longitudes given:

Const  Longitude

Sgr      0.0 -  14.9
SerCd   14.9 -  17.2
Sct     17.2 -  28.6
Aql     28.6 -  35.4
SerCd   35.4 -  36.7
Aql     36.7 -  51.5
Sge     51.5 -  54.9
Vul     54.9 -  66.3
Cyg     66.3 - 100.4
Cep    100.4 - 108.9
Cas    108.9 - 109.0
Cep    109.0 - 111.5
Cas    111.5 - 141.3
Cam    141.3 - 141.6
Per    141.6 - 141.9
Cam    141.9 - 149.3
Per    149.3 - 161.0
Aur    161.0 - 180.5
Tau    180.5 - 186.7
Gem    186.7 - 188.7
Ori    188.7 - 199.0
Gem    199.0 - 199.5
Mon    199.5 - 225.6
CMa    225.6 - 232.2
Pup    232.2 - 257.0
Vel    257.0 - 283.6
Car    283.6 - 292.1
Cen    292.1 - 296.5
Cru    296.5 - 303.7
Cen    303.7 - 316.3
Cir    316.3 - 323.5
Nor    323.5 - 336.8
Ara    336.8 - 339.4
Sco    339.4 - 358.7
Oph    358.7 - 359.3
Sgr    359.3 - 360.0

A number of constellations are entered twice, as their boundaries have edges. Some are merely touched by a short piece of the Galactic Equator (e.g. Ophiuchus), others (like Cygnus or Cassiopeia) contain long parts of it.

Hartmut Frommert
Christine Kronberg
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Last Modification: August 20, 2001