Star Constellations: The Zodiac

Star Constellations the Zodiac

There are 88 modern constellations occupying different regions of the sky, with the 12 zodiac constellations situated within a 9° band either side of the ecliptic plane, an imaginary line which traces the apparent path that the Sun, Moon, and planets take over the course of a year. The ecliptic encircles the celestial sphere at an angle of 23.5° relative to the celestial equator, with all the zodiac constellations located along this plane visible to stargazers at different times of the year from latitudes between +90° and -60°.

In astronomy, the degrees of longitude marking each zodiac constellations are not equally sized, and 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 also 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)

Astrology

In astrology, the zodiac constellations familiar to us as astrological star signs are neatly divided into 12 segments of sky 30° of longitude wide, with the Sun spending around one month in each star sign as it makes its annual trek across the sky. A person’s ‘star sign’ is then determined by which zodiac constellation the Sun is in front of at the time of their birth, but 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. Due to precession, however, the zodiac constellation the Sun appears in front of during any month no longer corresponds to the horoscope dates one reads about in the newspapers, but where it would have been several thousand years ago.

Zodiac Constellations

Capricornus

CapricornusCapricornus (“sea-goat”) is the smallest of the 12 zodiac constellations, and the 40th largest constellation in the night sky overall, taking up a 1.0% area of the celestial heavens. It is visible during the summer and autumn time from northern hemisphere locations, although 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. Deep-Sky Objects (DSOs) in the constellation includes a globular cluster (Messier 30), a galaxy group (HCG 87), and some galaxies (NGC 7103, and NGC 6907). Meteor showers associated with Capricornus includes the Alpha Capricornids, Chi Capricornids, Sigma Capricornids, Tau Capricornids, and Capricorniden-Sagittarids.

Aquarius

AquariusAquarius (“water-carrier”) is the 2nd biggest zodiac constellation, and the 10th largest constellation overall, taking up a 2.4% area of the sky. It is visible during the autumn and winter time from northern hemisphere locations, although 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. Deep-Sky Objects (DSOs) in the constellation includes 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

PiscesPisces (“fishes”) is the 4th biggest zodiac constellation, and the 14th largest constellation overall, taking up a 2.2% area of the sky. It is visible in the northern hemisphere between late summer and winter, although 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. Deep-Sky Objects (DSOs) in the constellation includes 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

AriesAries (“fishes”) is the 11th biggest zodiac constellation, and the 39 largest constellation overall, taking up a 1.1% area of the sky. In the northern hemisphere, it 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. Deep-Sky Objects (DSOs) in the constellation includes 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

TaurusTaurus (“bull”) is the 6th biggest zodiac constellation, and the 17th largest constellation overall, taking up a 1.9% area of the sky. In the northern hemisphere, it is visible during the autumn and winter time, although 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. Deep-Sky Objects (DSOs) in the constellation includes 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

GeminiGemini (“twins”) is the 8th biggest zodiac constellation, and the 30th largest constellation overall, taking up a 1.2% area of the sky. It is visible during the winter to spring time from northern hemisphere locations, although 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. Deep-Sky Objects (DSOs) in the constellation includes 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

CancerCancer (“crab”) is the 9th biggest zodiac constellation, and the 31st largest constellation overall, taking up a 1.2% area of the sky. It is visible during autumn to spring from northern hemisphere locations, although 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. Deep-Sky Objects (DSOs) in the constellation 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

LeoLeo (“lion”) is the 3rd biggest zodiac constellation, and the 12th largest constellation overall, taking up a 2.3% area of the sky. It is visible during the winter to spring time from northern hemisphere locations, although 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. Deep-Sky Objects (DSOs) in the constellation 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

VirgoVirgo (“virgin”) is the largest zodiac constellation, and the 2nd largest constellation overall, taking up a 3.1% area of the sky. It is visible during the spring and summer time from northern hemisphere locations, although 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. Deep-Sky Objects (DSOs) in the constellation 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

LibraLibra (“weighing scales”) is the 7th biggest zodiac constellation, and the 29th largest constellation overall, taking up a 1.3% area of the sky. It is visible during the spring and summer time from northern hemisphere locations, although 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. Deep-Sky Objects (DSOs) in the constellation includes 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

ScorpiusScorpius (“scorpion”) is the 10th biggest zodiac constellation, and the 33rd largest constellation overall, taking up a 1.2% area of the sky. It is visible during the summer time from northern hemisphere locations, although best seen during the month of July. The brightest star in Libra is Antares (Alpha Scorpii), a red supergiant found 550 light years from Earth that shines with a visual magnitude of +0.96. Deep-Sky Objects (DSOs) in the constellation 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

SagittariusSagittarius (“archer”) is the 5th biggest zodiac constellation, and the 15th largest constellation overall, taking up a 2.1% area of the sky. It is visible during the autumn time from northern hemisphere locations, although 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 deep-sky objects (DSOs) , including 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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