ORION (Pronounced oh-RYE-un), the Hunter

Chart showing Orion

Orion, the Hunter, has been admired throughout historical times as one of the most brilliant, recognisable and symmetrical constellations. Orion straddles the celestial equator, making it visible equally well from both hemispheres. Ptolemy assigned thirty-eight stars to it, including the nebulous one remarked about in very early times.

Many of the bright Orion stars are very hot, young and of early spectral type. This particularly applies to the multiple star θ Orionis or Trapezium where the very hot stars are radiating ultra-violet light causing the Orion nebula M 42 to fluorescence, making the glow that we see. These stars are burning hydrogen so rapidly that their lives cannot be long. In the Orion nebula stars are still being formed from the huge gas and dust cloud.

Two huge star associations that are too large to be telescopic objects have been identified. One is in the region of Orion's belt, and is surrounded by a large, very faint nebula known as Barnard's Loop. The other is associated with faint nebulosity around l Ori.

To find Orion, look towards the north late evening. Find the "Pot".

Chart showing Orion as seen high in the sky to the north mid evening in January.

Constellation Orion

Constellation Eridanus Constellation Lepus Constellation Canis Major Constellation Monoceros Constellation Gemini Constellation Taurus

Details of some of the objects shown in the chart.

The Great Nebula in Orion M42 (NGC 1976) is one of the most attractive objects in the sky. It can be seen with the unaided eye, looks beautiful in binoculars, and is stunning through a telescope. Visually, it appears different from pictures, since photographs cannot cope with the large brightness range between the Trapezium stars and the fainter nebula. In three dimensions the nebula is like an apple with a bite taken out, exposing the pips (the Trapezium stars). The Trapezium stars have blown out the "bite" from the apple (the gas and dust cloud).

α Ori, Betelgeuse (pronounced BET'l-jooz) (Armpit of the Central One) is an irregular variable star of low density that pulsates in and out. Its diameter is about 800 times the diameter of the Sun or 7.5 times the diameter of Earth's orbit. It lies 310 light years away.

β Ori, Rigel (pronounced RYE-j'l) (Giant's leg) at magnitude 0.1 is the brightest star in Orion. It is a blue-white supergiant 910 light years away.

γ Ori, Bellatrix (pronounced beh-LAY-trix) (the conqueror) magnitude 1.70 is a blue giant star 360 light years away.

κ Ori, Saiph (the sword) is a magnitude 2.20 blue supergiant 1,300 light years away.

The "Belt" stars are three bright stars of similar brightness. They are:

δ Ori, Mintaka (pronounced min-TARK-ah) (the belt), at magnitude 2.50, is a complex multiple star.

ε Ori, Alnilam (pronounced al-NIGH-lam) (string of pearls), magnitude 1.80 is a blue supergiant 1200 light years away.

ζ Ori, Alnitak (pronounced al-NIGH-tak) (the girdle), magnitude 2.00 is a blue white star 1100 light years away with a close 4.2 magnitude companion.

Visibility

The three bright stars forming the line of Orion's belt, with the four bright stars at the corners of a tall near rectangle, make Orion possibly the most recognisable of the constellations. From New Zealand it is visible to the northwest in the late evening by the end of November. By mid January it is to the north and at its highest.

With the lengthening dark evenings, the constellation remains visible in the early evening into May. By the end of May, as the evening sky darkens Orion is visible low to the west, lying on its side with Rigel to the left, Betelgeuse to the right and the belt nearly vertical.

In the pre-dawn morning sky, Orion is first visible about the beginning of July a little to the north of east. Rigel is then uppermost and the belt almost horizontal.

OPHIUCHUS, pronounced OFF-ee-YOO-kuss and SERPENS pronounced SUR-penz

Chart showing the constellations.

Ophiuchus is an ancient constellation representing a man coiled by a serpent (the constellation Serpens). Ophiuchus is identified by some as Aesculapius a mythical healer and forerunner of Hippocrates. Aesculapius served as ship's doctor on the Argo of Jason and the golden fleece legend. Another interpretation sees this constellation as Enkidu, the companion of Gilgamesh, who circles head-to-head with Ophiuchus in the sky, in the form of the constellation Hercules. The most celebrated star in Ophiuchus is a 9th magnitude red dwarf star, too faint to be seen with the unaided eye.

Barnard's Star at 6 light years away is the 2nd closest star to the Sun. Barnard found in 1916 that it has the greatest proper motion of any star; it appears to covers a distance equal to the diameter of the Moon every 180 years. The southern regions of Ophiuchus extend into the rich star fields of the Milky Way, looking towards the centre of the Galaxy. Ophiuchus was the site of the last supernova seen to erupt in our Galaxy in 1604.

Serpens represents the serpent wound round Ophiuchus. Serpens is split into two halves: Serpens Caput, the head; and Serpens Cauda, the tail.

To find Ophiuchus and Serpens look towards the North about half way between the horizon and the zenith. Ophiuchus is suppose to look like a teapot but to us that object will be upside-down.

Chart showing Ophiuchus and Serpens as seen in the sky to the north mid evening in August.

Ophiuchus and Serpens

Constellation Libra Constellation Scorpius Constellation Sagittarius Constellation Scutum Constellation Aquila Constellation Hercules

Some stars and interesting objects in the Constellation

α Ophiuchi (Ras Alhague, head of the serpent charmer) is a magnitude 2.1 white star 62 light years away.

α Serpentis (Unakalhai, serpent's neck) is a magnitude 2.7 orange giant star 85 light years distant.

M 10 (NGC 6254) is a 7th magnitude globular cluster about 19,000 light years away, visible in binoculars and small telescopes. Larger telescopes will begin to resolve individual stars in the cluster, showing two straight rays of four or five stars to the north.

M 12 (NGC 6218) is another 7th magnitude globular cluster slightly closer than M 10. It appears slightly larger than M 10 and has a more loosely scattered appearance.

M 5 (NGC 5904) is a 6th magnitude globular cluster 27,000 light years away, visible in binoculars or small telescopes. It is regarded as one of the finest globular clusters in the northern sky. Reasonable sized telescopes reveal a brilliant condensed centre and apparent chains of stars radiating outwards. Close by is 5 Serpentis, a 5th magnitude star with a 10th magnitude companion.

M 16 (NGC 6611) is an irregular, hazy looking cluster about 8,000 light years away. It consists of about 50 stars of 8th magnitude and fainter in an area about the apparent diameter of the Moon, embedded in a nebula known as the Eagle. The Eagle nebula is a famous Hubble telescope picture showing star formation from a dusty cloud. The Eagle nebula while faint, is made more visible with an OIII or other nebula filter.

NGC 6633 is a bright irregular scattered cluster of about 65 stars about 1,600 light years away, visible in binoculars, or even the unaided eye from a dark sky site.

IC 4665 is a loose and irregular cluster of a dozen or so stars of magnitude 7 or fainter, about 1,000 light years away requiring a wide field, such as binoculars. There is a "Y" shaped asterism in the north-eastern portion of the cluster.

NGC 6572 is a 10th magnitude planetary nebula, 2,500 light years away, visible in a telescope as a tiny blue-green ellipse.

Alya, θ Serpentis is an elegant pair of white stars magnitude 4.1 and 5.0, 100 light years away. There is an orange star slightly (7') north east, contrasting with the attractive wide pair.

Visibility

Ophiuchus and Serpens are visible to the north from New Zealand at about 9.30 pm NZST on August 1, 8.30 pm August 16 and 7.30 pm August 31.
During July the two constellations are to the north-east in the early evening, moving to be to the north by about 11.30 pm July 1 and 10.30 pm mid July.
During September and early October the constellations will be to the north-west shortly after the sky gets dark in the evening.  They are low to the west in the evening twilight by mid October and are lost in the evening twilight by the end of the month.

OCTANS, the OCTANT, Pronounced OCK-tanz

Chart showing the constellations.

Octans (originally Octans Hadleianus) was established by Nicolas Louis de Lacaille in 1752 to commemorate the invention of the octant (a navigational instrument before the sextant) by John Hadley in 1730. It occupies the rather barren region around the south celestial pole - the point in the sky about which the stars appear to rotate. The stars are not designated in magnitude sequence, for the brightest is the magnitude 3.8 orange-yellow ν Octantis, while α Oct is only magnitude 5.1.

Unlike the northern hemisphere, there is no bright star like Polaris to mark the present position of the south Celestial Pole. The nearest star is the dim magnitude 5.5 σ Octantis, which is just over 1° from the pole.

To find Octans look towards the south half way up the sky. Octans is about half way from the Pointers to the Southern Cross and Achernar (the bright star that the Cross appears to point to). Or alternatively extent the long arm of the Cross about three times.

Chart showing Octans, and Constellations round the S Pole - as seen about 9.00 pm mid August.

Octans. 10.6 kb

Constellation Grus Constellation Indus Constellation Pavo Triangulum Australe Constellation Apus Constellation Circinus Constellation Centaurus Constellation Crux Constellation Musca Constellation Vela Constellation Carina Constellation Volans Constellation Chamaeleon Constellation Mensa Constellation Dorado Constellation Hydrus Constellation Horologium Constellation Reticulum Constellation Eridanus Constellation Tucana Constellation Phoenix

Some stars in the Constellation

α Octantis is a magnitude 5.1 white star 148 light years away.

β Oct is a magnitude 4.2 white star 140 light years away.

δ Oct is a magnitude 4.3 orange giant star 112 light years away.

θ Oct is a magnitude 4.8 orange giant star 221 light years away.

λ Oct is a pair of stars 36 light years away shining at magnitudes 5.5 and 7.6, individually visible in small telescopes. It appears to be a long period binary, with the only change being slow retrograde motion since John Herschel's measures in 1836. The system lies 435 light years away.

ν Oct is a magnitude 3.8 orange giant star 69 light years away. It is the brightest star in the constellation.

σ Oct (Polaris Australis) with a magnitude 5.4 is the rather faint Pole Star for Southern skies.

Visibility

Being the pole constellation, Octans is visible all year in the Southern hemisphere. Its orientation in the sky will gradually rotate throughout the year. The main part of the constellation is highest in mid evening during August and September.

MUSCA (Pronounced MUS-Ka)

Chart showing the constellation.

Musca, the Fly, was originally Apis the Bee, made by Bayer about 1603. Later Edmund Halley of comet fame called it Musca Apis and later still Lacaille called it Musca Australis, since simplified to Musca.

To find Musca look south late evening and find Crux, the Southern Cross. Look underneath and find the Trapezium shape of Musca. The long axis of the Southern Cross almost points at it

The most prominent feature from a dark site with a transparent sky is the Coalsack, which lies in part of Crux, Musca and Centaurus. Since the constellation lies near a bright part of the Milky Way it renders conspicuous a large irregular dark nebula called the Coal Sack. This cloud of gas and dust lies about 600 light years away. Because there are no bright hot stars nearby it does not fluoresce and glow but absorbs light. To the aborigines of Australia the Coalsack is the head of the "Emu". There is a dark rift in the Milky way going north from the Coalsack, making the neck. Look on a dark night at the dark areas, rather than the stars and bright areas.

Chart showing Musca as seen to the south at about 10 pm early May or 8 pm at the end of May.

Musca constellation

Constellation Crux Constellation Vela Constellation Carina Constellation Volans Constellation Chamaeleon Constellation Lupus Constellation Octans Constellation Apus Trianglum Australe Constellation Circinus Constellation Centaurus

Some stars and interesting objects in Musca

α Muscae is a magnitude 2.7 blue-white star 330 light years away.

β Mus is a long period binary pair of bright white stars (magnitudes 3.9 and 4.2) in a starry field. A telescope of 12.5 cm. will separate the stars on a night with good seeing.

δ Mus is a magnitude 3.6 orange giant star 180 light years away.

θ Mus is an elegant white pair, in a field sown with stars. The bright star is the second brightest Wolf-Rayet (pronounced Volf Ray-eh) binary in the sky. These rare stars have hot surfaces and appear to eject gas. Deep photographs show a faint ring nebula surrounding the star.

NGC 4372 is a globular cluster partially obscured by a long lane of dark absorbing matter, similar to the Coalsack. It is a large globular about 16,000 light years distant.

NGC 4833 was recorded by Lacaille in 1752 as resembling a small faint comet. It is, however a beautiful well resolved and fairly compact globular cluster, with small outliers scattered over and beyond it in small curved lines. It lies about 17,000 light years away.

NGC 5189 is a remarkable planetary nebula discovered by John Herschel in 1835 and described by him as 'a very strange object'. The appearance in a beautiful starry field is strongly reminiscent of a barred spiral galaxy, leading to its popular name: the "Spiral Planetary".

Visibility

Musca is nearer the celestial south pole than Crux, so, like Crux, is circumpolar, that is always above the horizon, for New Zealand. The constellation is not visible from places with a latitude north of about 20° north.

The constellation is highest and due south at about 9.30 pm, NZST, in mid May.

MONOCEROS (pronounced moh-NOSS-er-us), the Unicorn

Chart showing Monoceros

Monoceros, the unicorn, has been attributed to Jakob Bartsch, a German mathematician, and son-in-law of Johannes Kepler, who brought it into general use on his star charts of 1624. However, it seems to have been formed much earlier, Scaliger having found it on a Persian sphere in the previous century. Its location in the Milky Way ensures that it is well stocked with nebulae and clusters.

To find Monoceros look towards the north to find the "Pot" of Orion. Find the bright stars Sirius and Procyon and look at the area between them.

Chart showing Monoceros as seen to the northwest about 10 pm towards the end of March.

When Monoceros is due north, rotate the chart clockwise so that Monoceros looks like an upright capital M.

Monoceros and surrounding constellations

Constellation Canis Major Constellation Puppis Constellation Hydra Constellation Canis Minor Constellation Cancer Constellation Gemini Constellation Orion Constellation Lepus

Details of some of the objects shown in the chart.

α Monocerotis is a magnitude 3.9 orange giant star 180 light years away.

β Mon is a beautiful white triple star. William Herschel discovered it in 1781 and thought it 'one of the most beautiful sights in the heavens'.

The smallest of telescopes should separate the three components of magnitudes 4.5, 5.2,and 5.6, on a good night. They form a curving arc of blue-white stars, the faintest two being closest together. There is evidence that one component is a spectroscopic binary, and as well a close speckle companion was discovered to another component in 1988. This is probably a quintuple star system.

δ Mon is a magnitude 4.2 blue-white star 210 light years away. It has a wide unrelated unaided eye companion of magnitude 5.5.

ε Mon is an easy double star for small telescopes, consisting of yellow and blue components of magnitude 4.3 and 6.7, 180 light years away.

M 50 (NGC 2323) is a large splendid open cluster of about 100 stars, visible in binoculars and small telescopes. Many of the stars are in pairs, triplets and small groups, while a bright orange star is close to the centre of the group.

NGC 2232 is a scattered irregular open cluster surrounding the 5th magnitude blue-white star 10 Mon. It is visible in binoculars and small telescopes.

NGC 2244 is a bright scattered cluster, lying mostly in a dark space around which is a large band of luminosity - the Rosette Nebula (NGC 2237/46). The cluster is visible in binoculars or small telescopes. Large apertures or an OIII filter are needed to be able to see the Rosette Nebula.

NGC 2261 is a fan shaped nebula known as Hubble's variable nebula. It has the variable star R Mon at the apex. Changes in its form have been observed for more than a century. These are partly caused by the variability of the star which varies between magnitudes 9.5 to 12

NGC 2301. This bright open cluster in a beautiful field is well suited for binoculars or small telescopes. There is an orange star in the roughly round central region.

NGC 2264 is a combination of star cluster and nebula. The cluster is visible in binoculars or small telescopes, contains about 20 members, including the 5th magnitude star S Mon - an intensely blue-white slightly variable star with a close companion. The nebula is known as the cone nebula, because of its tapered shape. It shows up well on long exposure photographs, but is visually very difficult to see, requiring a Hb filter

Visibility

Monoceros straddles the celestial equator and can be viewed in the evening from the beginning of the year until early June. It is due north at about 11.30 pm in mid February and 2 hours earlier mid March. When due north, Monoceros is to the right of Orion and below Canis Major.


LYRA, the Lyre. (Pronounced LIR-rah)

Chart showing the constellation.

This is one of the very old constellations, which represents the stringed musical instrument invented by Hermes in the Homeric myth. Hermes half-brother Apollo gave this harp like instrument, to Orpheus. The Greek astronomer Ptolemy in 150 AD assigned ten stars to the constellation. Lyra contains Vega, the fifth brightest star in the sky. Vega forms one corner of the northern hemisphere's famous "Summer Triangle" together with the bright stars Deneb and Altair.

Our Sun's motion around the Milky Way Galaxy is carrying it and the Solar System in the direction of Vega at a velocity of 20 km per second. Because of a slow wobble in Earth's axis called precession, Vega will be the northern pole star instead of the present Polaris in around 14,000 years.

To find this constellation look low to the north in the evening sky, and find the bright star Vega.

Chart showing Lyra and surrounding constellations, looking north at about 9.30 pm (NZST) mid August.
The horizon shown is for central New Zealand, latitude about 41.5°S.

Lyra chart

Constellation Hercules Corona Borealis Constellation Cygnus Constellation Aquila Constellation Aquarius Vulpecula & Sagitta Ophiuchus & Serpens Delphinus & Equuleus Constellation Scutum

Some stars and interesting objects in the Constellation

α Lyrae (Vega) is a close brilliant blue-white star 25 light years away, varying in brightness between magnitudes -0.02 and 0.07.

β Lyr (Sheliak) is a remarkable multiple star 882 light years away. Small telescopes easily resolve it as a double star with cream and blue components. The fainter blue star is of magnitude 7.8; the brighter star is an eclipsing binary that varies between magnitudes 3.4 and 4.3 every 12.93 days. The stars are very close, egg shaped from the mutual tidal action, and hot gas spirals off from them into space.

γ Lyr is a magnitude 3.22 blue-white star 635 light years away.

δ Lyr is a wide unaided eye, or binocular double, consisting of two unrelated stars. One is a magnitude 5.56 blue-white star 1080 light years away, while the other is a red giant star 899 light years away. This star varies between magnitudes 4.22 and 4.33. Both stars are also actual double stars as well.

ε Lyr is a celebrated quadruple star commonly called the double double, though speckle interferometry has shown that one of the pairs has a close companion, so this is actually a quintuple system. It is easily separated into two stars (magnitudes 4.7 and 5.1) by binoculars, or even keen eyesight, but in a telescope with high magnification, each star is seen to be double. The double systems are 160 and 162 light years away.

ζ Lyr is a pair of stars of magnitudes 4.32 and 5.59, 154 and 150 light years away. It is easily split in small telescopes or good binoculars.

η Lyr is a magnitude 4.5 blue-white star with a wide magnitude 11.1 companion, visible in small telescopes. It lies 1042 light years away.

RR Lyr is giant star 745 light years away, the prototype of an important class of variable stars used as 'Standard Candles' for measuring distances in space. It varies from magnitudes 7.06 to 8.12 every 0.57 days.

M 57 (NGC 6720) the Ring Nebula was described by John Herschel as 'gauze stretched over a hoop'. A comet passed by this planetary nebula in 1779 and led to its discovery by Messier. Long exposure photographs with large telescopes show it as a looking like a celestial smoke ring, but small telescopes show it as a noticeably elliptical misty disc. It is one of the brightest planetary nebula, appearing larger in the sky than the planet Jupiter.

Visibility

Lyra is well north of the celestial Equator and so is always low from New Zealand. The entire constellation is visible from the North Island and the extreme north of the South Island. South of latitude 42° 24' south (Kaikoura and Greymouth), the most northerly parts of the constellation do not rise above the horizon. From Auckland, Vega culminates at 14° above the northern horizon. From Invercargill, the star has a maximum altitude of 4.5°.

From the latitude of New Zealand, Lyra can be seen to the north from early April to late September. In April it will be visible about an hour before sunrise, in September about an hour after sunset.

LYNX "The Lynx"; pronounced LINKS

Chart showing the constellation.

LYNX was made by Johannes Hevelius, the Polish astronomer about 1660 from 19 stars to fill a gap between Auriga and Ursa Major. He named it Lynx, because only the lynx-eyed would be able to see it. It is rather low in the northern sky, and not all the constellation is visible from New Zealand. On the chart the horizon is for Auckland; residents of Christchurch would see from the constellation name up; while Invercargill viewers may just see 31 Lyncis on the horizon.

Apart from α Lyncis, all the named stars are referred by Flamsteed numbers instead of Greek letters. These numbers are from a catalogue of 2935 stars Historia Coelestis Britannica compiled by the first British Astronomer Royal, John Flamsteed (1646-1719). This catalogue was published posthumously in 1725, and listed the stars in each constellation in order of right ascension. The numbers, now known as Flamsteed numbers, were not given by him, but were added later by other astronomers.

To find Lynx look very low to the north, away from city lights under an area between the Gemini twins Castor and Pollux, and Regulus.

Chart showing the constellation as seen to the north at about 11.00 pm NZDT in mid March.

The chart is also valid for about 8pm NZST mid April and 7pm at the beginning of May.

Constellation Lynx.

Constellation Cancer Constellation Leo Constellation Leo Minor Constellation Gemini Constellation Auriga Constellation Canis Minor Constellation Hydra Constellation Ursa Major

Details of some of the objects shown in the chart.

α Lyncis is a magnitude 3.1 red giant star 222 light years away.

31 Lyn is another red giant star, magnitude 4.2 and about 400 light years away.

38 Lyn is a fine bright pair of 4th and 6th magnitude stars, difficult in small telescopes because of their closeness. In 1988, the less bright star was found by speckle interferometry to be a close pair, making this a triple star system. The system lies 122 light years away.

41 Lyn is really over the border in Ursa Major. It is a magnitude 5.4 yellow star, but small telescopes revel a magnitude 7.8 wide companion star. A 10th magnitude star nearby forms a triangle, making this an apparent triple star 288 light years away.

Visibility

α Lyncis has a maximum altitude of about 18° from Auckland, 12° from Christchurch and 9° from Invercargill. The parts of the constellation which are visible from New Zealand are only above the horizon for a few hours at the most.

LUPUS "The Wolf" (pronounced LOO-puss)

Chart showing the constellation.

This ancient constellation was designated in the Almagest of Ptolemy in the second century AD as a wild beast, held in the grasp of Centaurus as an offering to the gods. The unspecified wild beast seems to have become a wolf in Renaissance times.

To find this constellation look high to the north in the evening sky, find the red star Antares in Scorpius the Scorpion and the Pointers to Crux, the Southern Cross. Lupus lies in the Milky Way between them.

View facing north with Lupus overhead, at about 9.00 pm at the beginning of July.

Lupus constellation

Constellation Crux Constellation Centraurus Constellation Ophiuchus Constellation Circinus Triangulum Australe Constellation Norma Constellation Ara Constellation Telescopum Constellation Scorpius Constellation Libra Constellation Hydra Constellation Virgo

Some stars and interesting objects in the Constellation

α Lupi is a pulsating blue giant star varying between magnitudes 2.29 and 2.34. It lies 548 light years away.

β Lup is a magnitude 2.62 blue-white star 524 light years away.

γ Lup is a magnitude 2.97 blue-white star 567 light years away.

ε Lup is a multiple star system 504 light years away. The blue-white primary star is magnitude 3.37, while the secondary star is magnitude 4.85. The primary is also a spectroscopic double star.

η Lup is white and ashy pair of stars of magnitudes 3.4 and 7.7 lying 493 light years away. This double is not easy to see in small telescopes because of the magnitude difference.

κ Lup is an easy double star for small telescopes. A bright pale yellow pair of stars of magnitudes 3.88 and 5.70 dominate a striking field. The system lies 182 light years away.

μ Lup is a multiple star with three components. The close pair needs a telescope of 10.5 cm aperture or more to resolve them. The wider companion looks slightly reddish. The field is sown with stars making the effect very attractive. The primary star is reasonably bright with magnitude 3.88.

ξ Lup is a beautiful pair of stars in a field of scattered stars. This is well seen in small telescopes. The stars are of magnitudes 5.14 and 5.59 and lie 199 light years away.

π Lup is clearly resolved into a pair of stars with moderate apertures. The magnitudes of the two similar blue-white stars is around 4.5 and they lie 497 light years away.

NGC 5822 is a large loose cluster of stars needing a large field to be seen plainly. Small apertures show patterns of lines of stars. It is estimated as 2,000 light years away.

NGC 5986 is a globular cluster, seen as a hazy spot in smaller telescopes. It lies about 35,000 light years away.

NGC 5927 is a broadly compressed globular cluster in a fine starry field, lying about 25,000 light years away.

Visibility

Lupus passes overhead as seen from New Zealand, with the more southerly parts of the constellation being cicumpolar, that is not setting, as seen from the South Island. The constellation is overhead at about 10pm in mid June and 8 pm mid July.

Because of its southerly declination, Lupus is visible for at least part of the night throughout the year.

LIBRA, the SCALES, pronounced LEE-brah

Chart showing the constellation.

Libra the Scales or Balance is the seventh zodiacal constellation. The ancient Greeks knew it as the "Claws of the Scorpion", an extension of neighbouring Scorpius, but the Romans made it into a separate constellation in the time of Julius Caesar. Since then the Scales of Libra have become regarded as the symbol of justice, held aloft by the goddess of justice, Astraea. One legend identifies Astraea with the neighbouring figure of Virgo.

The four principal stars of Libra form a trapezium preceding the head of Scorpius.

To find Libra look towards the north in the evening sky and find orange Antares the heart of Scorpius, the scorpion. Libra is to the left of the head of Scorpius.

Chart showing the constellation as seen to the north just before 8 pm mid July.

Libra constellation

Constellation Centaurus Constellation Hydra Constellation Lupus Constellation Scorpius Constellation Sagittarius Constellation Scutum Constellation Serpens Constellation Ophicuhus Constellation Serpens Constellation Virgo

Some stars and interesting objects in the Constellation

α Librae (Zubenelgenubi, the southern claw), is a wide binocular double consisting of a blue-white magnitude 2.8 star with a white companion of magnitude 5.2. It is 77 light years away.

β Lib (Zubeneschamali, northern Claw), is a magnitude 2.6 star, celebrated as one of the few bright stars with a greenish tinge. It lies 160 light years away.

γ (Zubenelakrab, scorpion's claw), is a magnitude 3.9 yellow giant star 152 light years away.

δ Lib is a white eclipsing variable star of the Algol type 304 light years away. It varies between magnitudes 4.8 and 5.9 every 2.327 days. Here the eclipse of the brighter star by the larger but fainter star is only partial.

ι Lib is a multiple star 377 light years away. Its main blue-white magnitude 4.5 component star has a 10th magnitude faint equal pair accompanying it. The bright star is a close binary and there is spectroscopic evidence for another component to the bright star, so the system is probably quintuple.

μ Lib is a pair of pale yellow stars 235 light years away shining at magnitudes 5.8 and 6.7.

48 Lib is a magnitude 4.9 shell star. It is a blue giant 513 light years away, with an abnormally high speed of rotation that causes it to throw off a ring of gas from its equator.

NGC 5897 is a large irregularly round globular cluster 42,000 light years away. It appears loosely scattered and unspectacular in small telescopes.

Visibility Libra is to the north in New Zealand at 9 pm early in July. It is visible at this time of night from early April, when it will have just risen, to early October when it will be close to setting.

LEO (pronounced LEE-oh)

Chart showing Leo and Leo Minor

Leo, the Lion is one of the few constellations that looks like the figure it is supposed to represent - in this case, a crouching lion, though this is upside-down to us in the southern hemisphere. The lion's head is outlined by a sickle shape of six stars with the body stretching out to the left. The tail is marked by β Leonis.

This lion is the one slain by Hercules as the first of his twelve labours. Ptolemy assigned 27 stars to the ancient constellation. Every year around November 17th, the Leonid meteors appear to come from a point near γ Leonis. Usually the numbers are low, but on occasions spectacular storms are recorded. These usually happen around each 33 years.

Leo Minor was introduced by Johannes Hevelius, the Polish astronomer, in the late 17th Century. There is little of interest, and the labelling of its stars is very fragmentary, testimony to the cavalier treatment by successive generations of celestial cartographers.

To find Leo look towards the north to find bright Regulus and the backward "sickle" shape below. Leo Minor is below.

Chart showing Leo and Leo Minor as seen to the north at about 10 pm on April 15 or 8 pm on May 15.

Leo and Leo Minor.

Constellation Hydra Constellation Sextans Constellation Crater Constellation Virgo Coma Berenice Canes Venatici Ursa Major Constellation Lynx Constellation Gemini Constellation Cancer

Details of some of the objects shown in the chart.

α Leonis (Regulus) is a magnitude 1.4 blue-white star 85 light years away. It has an orange-red companion magnitude 7.6, visible in binoculars or small telescopes. This companion is also binary but its faint companion is difficult to see.

β Leo (Denebola, lion's tail) is a magnitude 2.1 white stars 42 light years away.

γ Leo (Algeiba, lion's mane) at 100 light years away, is a beautiful pair of stars easily seen in small telescopes, with a period of about 600 years. The stars are golden-yellow giants of magnitudes 2.3 and 3.5. In binoculars, an unrelated 5th magnitude yellow star is visible nearby.

δ Leo (Zosma) is a magnitude 2.6 blue-white star 52 light years away.

ζ Leo (Adhafera) is a magnitude 3.4 white star 120 light years away. Binoculars show an unrelated orange background star nearby of magnitude 5.8. A 3rd star of magnitude 6.0 and also unrelated can be seen father off in binoculars, making this an optical triple.

ι Leo is a close double star with components revolving round each other every 192 years. The magnitude 4.1 and 7.0 yellow-white stars lie 78 light years away.

M65 (NGC 3623) is an edgewise spiral with a bright central region. It has a long dark absorption lane near the eastern edge.

M66 (NGC 3627) is a spiral galaxy shining at magnitude 8. It can be detected in large binoculars and small telescopes, although larger instruments are need to see its spindle shape.

M95 (NGC3351) is photographically a beautiful spiral galaxy, but it appears as a 10th magnitude hazy spot in amateur telescopes. It forms a group of galaxies with M96, M105, and NGC 3384 at about 33,000,000 light years away.

M96 (NGC 3368) is a fine spiral galaxy with a bright inner region, shining at 9th magnitude.

M105 (NGC3379) is a round bright elliptical galaxy forming a triangle with M95 and M96. This galaxy is used as a photometric standard for extended objects.

Visibility

Leo lies on and to the north of the equator. Regulus is to the north at 10 pm at the beginning of April and at 8 pm and the end of the month. The constellation is visible early evening up to late July, when Regulus will set soon after 6 pm.

During 2009 the planet Saturn will be about 16° from Regulus and moving near the stars σ Leo, mag 4.0 and χ Leo, mag 4.6.