Autumn constellations are the constellations that are best observed in the night sky from late September to late December in the northern hemisphere and from late March to late June in the southern hemisphere.
Autumn is a good time to see a number of notable constellations, including the zodiac constellations of
Aquarius
,
Aries
and
Pisces
, and the constellations in the Perseus family:
Andromeda
,
Perseus
,
Cassiopeia
,
Pegasus
,
Triangulum
,
Cetus
and
Cepheus
.
Cassiopeia’s W
, the
Great Square of Pegasus
and
Lacerta
’s zig-zag shape make it easy to find them.
Autumn constellation map
Andromeda
, located right between the W and the
Great Square
, is best known for the
Andromeda Galaxy
(M31), the nearest major galaxy to our own, the Milky Way and the most distant object visible to the unaided eye. The galaxy is so large that it appears as a small cloud in binoculars and can be observed and photographed even in small telescopes. The smaller satellite galaxies
Messier 32
and
Messier 110
require larger telescopes.
Autumn constellation map, image: Wikisky
Alpheratz
, the brightest star in
Andromeda
, is a double star that was once considered to be part of both
Andromeda
and
Pegasus
. It marks the northeastern tip of the
Great Square of Pegasus
. The asterism, which represents the main body of the celestial horse, makes
Pegasus
easy to spot. It is formed by
Alpheratz
and
Pegasus
stars
Algenib
,
Scheat
and
Markab
.
Pegasus
is the seventh largest constellation in the sky. It contains a number of notable stars and deep sky objects, among them 51 Pegasi, the first Sun-like star discovered to have an orbiting planet, the bright globular cluster
Messier 15
(Great Pegasus Cluster), the spiral galaxy
NGC 7331
and the two unusual deep sky objects, the gravitationally lensed quasar known as Einstein’s Cross and
Stephan’s Quintet
, a striking visual grouping of five galaxies.
The Great Square of Pegasus, Andromeda, the Water Jar and the Circlet of Pisces, image: Wikisky
Perseus
is home to the famous eclipsing variable star
Algol
, two Messier objects ? the bright open star cluster
Messier 34
and
Little Dumbbell Nebula
(M76) ? as well as to the famous
Double Cluster
, the
California Nebula
(NGC 1499), and many other interesting deep sky objects.
Cassiopeia
’s brightest stars form a prominent W shape, which makes the constellation very easy to find. Like
Perseus
, the constellation is located in a rich section of the Milky Way and harbours a number of notable deep sky objects. These include the Messier open clusters
M52
and
M103
, the
Owl Cluster
(NGC 457),
Caroline’s Rose Cluster
(NGC 7789), and the open cluster NGC 663, the emission nebula
NGC 281
(the Pacman Nebula), the large
Heart
and
Soul Nebula
complex, the supernova remnants
Cassiopeia A
and Tycho’s Star, and the elliptical galaxies NGC 147 and NGC 185.
Cassiopeia field, image: Wikisky
Triangulum
is one of the
smallest constellations
, but easy to find in good conditions. Located just under
Andromeda
, the constellation has the shape of a long, narrow triangle. It is best known as the home of the
Triangulum Galaxy
(M33), the third largest member of the Local Group, after
Andromeda
and the Milky Way. Like the
Andromeda Galaxy
,
M33
is one of the most distant deep sky objects visible to the unaided eye, but it requires significantly better viewing conditions to be spotted without binoculars or a telescope because it is much more diffuse than
Andromeda
.
The zodiac constellations
Pisces
and
Aquarius
are among the
largest constellations
in the sky, 14th and 10th in size respectively, and can be easily identified by two prominent
asterisms
, the Circlet of Pisces and the
Water Jar
. The Circlet of Pisces, which represents the head of the Western Fish, is located between the
Great Square of Pegasus
and
Aquarius constellation
. The nearby
Water Jar
, a Y-shaped asterism also known as the Urn, represents the cup
Aquarius
, the Water Bearer, is holding as he pours water into the mouth of
Piscis Austrinus
, the Southern Fish.
Aquarius
contains several bright Messier objects ? the asterism
Messier 73
and the globular clusters
Messier 2
and
Messier 72
? as well as the famous
Helix Nebula
,
Saturn Nebula
and Atoms for Peace Galaxy (NGC 7252).
Pisces
is home to the
Phantom Galaxy
(M74), a face-on grand design spiral galaxy visible even in large binoculars.
Piscis Austrinus
, the Southern Fish, is relatively inconspicuous, but notable for containing
Fomalhaut
, one of the
brightest stars
in the sky.
Fomalhaut
is a white main sequence star located only 25 light years from Earth. It has a visual magnitude of 1.16.
The southern constellation
Octans
is invisible to northern observers, but can be seen from southern latitudes throughout the year. The constellation is home to the Southern Celestial Pole, which is located about a degree from the star
Sigma Octantis
, also known as Polaris Australis. With a visual magnitude of 5.42, it is the pole star in name only, as it can barely be seen by the unaided eye. Instead, the much brighter
Southern Cross
is used to determine the position of the pole.
Tucana
, which cannot be seen from locations north of latitude 25°N, does not contain any particularly bright stars, but is home to several interesting deep sky objects. It contains most of the Small Magellanic Cloud, the bright (mag. 2.7) dwarf irregular galaxy which is one of the Milky Way’s closest neighbours and appears as a fuzzy patch about 8 times the Moon’s diameter that is often confused for a piece of the Milky Way.
Tucana
is also home to
47 Tucanae
, the second brightest globular cluster in the sky and one of the most massive clusters in the Milky Way. With an apparent magnitude of 4.09, it is dimmer only than
Omega Centauri
. The cluster appears adjacent to the Small Magellanic Cloud, but is in fact more than 15 times closer to us than the galaxy.
Northern autumn constellations:
Southern autumn constellations
(below) correspond to northern
spring constellations
.