Star Constellations | The Zodiac

Star Constellations the Zodiac

In Western tradition, the 12 zodiac constellations originate from ancient astrological practices, with their names based upon the 12 signs of a horoscope. This family of zodiac constellations includes Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces.

In total, there are 88 star constellations in the sky with the 12 zodiac constellations traveling along a roughly 20° wide region of space called the ecliptic. This is the apparent path that the Sun, Moon, and planets seems to travel throughout a one year period (as shown above).

Since the Sun appears in front of a zodiac constellation during the daytime, the sight is obscured from view. If we could see the stars during the daytime, though, we would see the Sun slowly drift from one zodiac constellation to the next over time, as it completes one full circle around the sky every year.

Zodiac Constellations in Astrology vs. Astronomy

In astrology, the zodiac constellations familiar to us as astrology signs are neatly divided into 12 segments of sky 30° of longitude wide. The Sun then spends around one month in each of the zodiac signs as it makes its one annual 360° trek across the sky.

In astronomy, however, the degrees of longitude marking each zodiac constellation are not equally sized. As such, the number of days the Sun spends in each zodiac constellation varies accordingly. This can be seen in the following list (days in brackets), which includes an unofficial thirteenth zodiac constellation called Ophiuchus, whose modern boundary also intersects the ecliptic:

Sagittarius (32), Capricornus (23), Aquarius (24), Pisces (38), Aries (25), Taurus (37), Gemini (31), Cancer (20), Leo (37), Virgo (45), Libra (23), Scorpius (7), Ophiuchus (18).

Here are some key details about each of the 12 zodiac constellations, including their size, best viewing times, brightest star, and notable deep-sky objects.


Capricornus

Capricornus

Capricornus (“sea-goat”) is the smallest of the 12 zodiac constellations. It is the 40th largest constellation in the night sky overall, taking up a 1.0% area of the celestial heavens. Capricornus is visible during the summer and autumn time from northern hemisphere locations. It is best seen during the month of September.

The brightest star in Capricornus is Deneb Algedi (Delta Capricorni), a multiple star system situated 39 light years from Earth that shines with an apparent visual magnitude of +2.85. Notable deep sky objects in Capricornus include a globular cluster (Messier 30), a galaxy group (HCG 87), and some galaxies (NGC 7103, and NGC 6907). Meteor showers associated with Capricornus include the Alpha Capricornids, Chi Capricornids, Sigma Capricornids, Tau Capricornids, and Capricorniden-Sagittarids.

 


Aquarius

Aquarius

Aquarius (“water-carrier”) is the 2nd biggest zodiac constellation. It is the 10th largest constellation overall, taking up a 2.4% area of the sky. Aquarius is visible during the autumn and winter time from northern hemisphere locations. It is best seen during the month of October.

The brightest star in Aquarius is Sadalsuud (Beta Aquarii), a yellow supergiant found 610 light years away with a visual magnitude of +2.91. Notable deep sky objects in Aquarius include globular clusters (M2, M72), nebulae (NGC 7009, NGC 7293), and galaxies (PGC 65367, NGC 7252, NGC 7727). Meteor showers associated with Aquarius includes the March Aquariids, Eta Aquariids, and Iota Aquariids.


Pisces

Pisces

Pisces (“fishes”) is the 4th biggest zodiac constellation. It is the 14th largest constellation overall, taking up a 2.2% area of the sky. Pisces is visible in the northern hemisphere between late summer and winter. It is best seen during the month of November.

The brightest star in Pisces is Kullat Nunu (Eta Piscium), a yellow giant found 294 light years from Earth with a visual magnitude of +3.62. Notable deep sky objects in Pisces include numerous galaxies and galaxy groups (Messier 74, NGC 7537, NGC 383, PGC 4798, PGC 3792, NGC 7714 and NGC 7715, NGC 474, NGC 520, NGC 7459, NGC 514, NGC 57, NGC 60). Pisces has one meteor shower associated with it called the Piscids.


Aries

Aries

Aries (“ram”) is the 11th biggest zodiac constellation. It is the 39 largest constellation overall, taking up a 1.1% area of the sky. In the northern hemisphere, Aries is visible between winter and spring, although best seen during the month of December.

The brightest star in Aries is Hamal (Alpha Arietis), an orange giant 66 light years from Earth with a visual magnitude that ranges from +1.98 to +2.04. Notable deep sky objects in Aries include a number of faint galaxies (NGC 772, NGC 1156, NGC 972, NGC 697). There are 5 meteor showers associated with Aries, the most important of which is the May Arietids, with the other weaker showers including the Autumn Arietids, Delta Arietids, Epsilon Arietids, and Daytime-Arietids.


Taurus

Taurus

Taurus (“bull”) is the 6th biggest zodiac constellation. It is the 17th largest constellation overall, taking up a 1.9% area of the sky. In the northern hemisphere, Taurus is visible during the autumn and winter time. It is best seen during the month of January.

The brightest star in Taurus is Aldebaran (Alpha Tauri), an orange giant 65.1 light years distant with a visual magnitude of +0.87. Notable deep sky objects in Taurus include nebulae (Messier 1, NGC 1555, NGC 1514), star clusters (Messier 45, Caldwell 41, NGC 1746, NGC 1647, NGC 1817, NGC 1807) and galaxies (NGC 1410 and NGC 1409. Taurus has two meteor shower associated with it called the Piscids. Meteor showers associated with Taurus includes the Taurids, and Beta Taurids.


Gemini

Gemini

Gemini (“twins”) is the 8th biggest zodiac constellation. It is the 30th largest constellation overall, taking up a 1.2% area of the sky. Gemini is visible during the winter to spring time from northern hemisphere locations. It is best seen during the month of January.

The brightest star in Gemini is Pollux (Beta Geminorum), an orange giant that is found 34 light years away with a visual magnitude of +1.14. Notable deep sky objects in Gemini include nebulae (NGC 2392, IC 443, Abell 21, NGC 2371-2), and star clusters (Messier 35, NGC 2158, NGC 2129, NGC 2355). There are two meteor shower associated with Gemini of opposite intensity, namely the prolific Geminids, and the unspectacular Rho Geminids.


Cancer

Cancer

Cancer (“crab”) is the 9th biggest zodiac constellation. It is the 31st largest constellation overall, taking up a 1.2% area of the sky. Cancer is visible during autumn to spring from northern hemisphere locations. It is best seen during the month of March.

The brightest star in Cancer is Al Tarf (Beta Cancri), an orange giant situated 290 light years away of magnitude +3.5. Notable deep sky objects in Cancer include galaxies (NGC 2775, NGC 2535 & NGC 2536, NGC 2500, NGC 2608), and star clusters (Messier 44, Messier 67). The one meteor shower associated with Cancer is called the Delta Cancrids.


Leo

Leo

Leo (“lion”) is the 3rd biggest zodiac constellation. It is the 12th largest constellation overall, taking up a 2.3% area of the sky. Leo is visible during the winter to spring time from northern hemisphere locations. It is best seen during the month of April.

The brightest star in Leo is Regulus (Alpha Leonis), a multiple system lying 77 light years distant of magnitude +1.35. Notable deep sky objects in Leo include numerous galaxies (Messier 65, Messier 66, Messier 95, Messier 96, Messier 105, NGC 3628, NGC 3607, NGC 3593, NGC 3384, NGC 3842, NGC 3596, NGC 2903, NGC 3626, NGC 3357), as well huge quasar groups (CCLQG, Huge-LQG). There are four meteor shower associated with Leo, namely the famous Leonids, and the more minor Delta Leonid, Sigma Leonid, and Leo Minorids.


Virgo

Virgo

Virgo (“virgin”) is the largest zodiac constellation. It is also the 2nd largest constellation overall, taking up a 3.1% area of the sky. Virgo is visible during the spring and summer time from northern hemisphere locations. It is best seen during the month of May.

The brightest star in Virgo is Spica (Alpha Virginis), a multiple system situated 260 light years away of magnitude +1.04. Notable deep sky objects in Virgo include numerous galaxies (Messier 49, Messier 58, Messier 59, Messier 60, Messier 61, Messier 84, Messier 86, Messier 87, Messier 89, Messier 90, Messier 104, NGC 4435 & NGC 4438, NGC 4216, NGC 4567 & NGC 4568, NGC 4526, NGC 4261), and a quasar called 3C 273. The two meteor shower associated with Virgo includes the Virginids, and the Mu Virginids.


Libra

Libra

Libra (“weighing scales”) is the 7th biggest zodiac constellation. It is the 29th largest constellation overall, taking up a 1.3% area of the sky. Libra is visible during the spring and summer time from northern hemisphere locations. It is best seen during the month of June.

The brightest star in Libra is Zubeneschamali (Beta Librae), a blue-white dwarf lying 185 light years away of magnitude +2.61. Notable deep sky objects in Libra include galaxies (NGC 5792, NGC 5890, NGC 5897, NGC 5885), and the globular cluster NGC 5897. The one meteor shower associated with Libra is called the May Librids.


Scorpius

Scorpius

Scorpius (“scorpion”) is the 10th biggest zodiac constellation. It is the 33rd largest constellation overall, taking up a 1.2% area of the sky. Scorpius is visible during the summertime from northern hemisphere locations. It is best seen during the month of July.

The brightest star in Scorpius is Antares (Alpha Scorpii), a red supergiant found 550 light years from Earth that shines with a visual magnitude of +0.96. Notable deep sky objects in Scorpius include several star clusters (Messier 4, Messier 6, Messier 7, Messier 80, NGC 6281, NGC 6124, NGC 6231), and nebulae (NGC 6334, NGC 6072, NGC 6302, NGC 6357). Meteor showers associated with Scorpius includes the Alpha Scorpiids, and the Omega Scorpiids.


Sagittarius

Sagittarius

Sagittarius (“archer”) is the 5th biggest zodiac constellation. It is the 15th largest constellation overall, taking up a 2.1% area of the sky. Sagittarius is visible during the autumn time from northern hemisphere locations. It is best seen during the month of August.

The brightest star in Sagittarius is Kaus Australis (Epsilon Sagittarii), a binary system located 140 light years distant with a visual magnitude of + 1.85. Lying in a dense part of the sky, Sagittarius is rich in astronomical objects. Notable deep sky objects in Sagittarius include nebulae (Messier 8, Messier 17, Messier 20, NGC 6565, NGC 6578, Hubble 1925 I, NGC 6818, M 1-42, NGC 6589, Henize 3-1475, Westerhout 5, NGC 6537, NGC 6559), galaxies (Sgr dSph, Sag DIG, NGC 6822), and the molecular cloud Sagittarius B2.

It also contains numerous star clusters (NGC 6530, Messier 18, Messier 21, Messier 22, Messier 23, Messier 24, Messier 25, Messier 28, Messier 54, Messier 55, Messier 69, Messier 70, Messier 75, Arches Cluster, Quintuplet Cluster, NGC 6522, NGC 6528, NGC 6723, NGC 6544, 1806-20, Terzan 7, Terzan 5, NGC 6440, NGC 6445, NGC 6638, NGC 6624, NGC 6520, NGC 6717, Hurt 2, NGC 6553, NGC 6774, NGC 6558, NGC 6569, NGC 6540). There are no meteor showers associated with Sagittarius.

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