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Astronomers dream of nights where thousands of stars dazzle in pitch-black skies with the band of the Milky Way flowing like a great river from one side to another. Alas for most of us this is often just a dream. We live in towns and cities polluted by artificial lighting from streets, building and factories that significantly diminish our view of the night sky.
However, it's not all that bleak as things do seem to be improving. Recently more efficient street lights have been installed in many areas, significantly reducing the amount of light beamed up to the heavens rather than down on the ground. Of course there are always out of town regions, especially forests and mountainous areas, away from the bulk of civilisation where the beauty of the night sky still rules. But have you ever wondered, how dark are your night skies? One way to check is by looking towards the constellation of Pegasus.
Pegasus is the 7th largest constellation in the sky covering an impressive 1,121 square degrees. For Northern Hemisphere observers, it's easily recognisable during the autumn months. The prominent asterism known as "Great Square of Pegasus" dominates the constellation. It's made up of reasonably bright stars between 2nd and 3rd magnitude:
Scheat (β Peg) - mag. 2.44
Markab (α Peg) - mag. 2.49
Algenib (γ Peg) - mag. 2.83
Alpheratz (α And) - mag. 2.07
Aries
Arietis
Ari
The Ram
Introduction
Aries is a medium-sized northern constellation of the zodiac that lies in a rather barren part of the sky. It contains mostly inconspicuous faint stars and is bordered by Taurus to the east, Perseus and Triangulum to the north, Pisces to west and Cetus to the south. The constellation was one of the original 48 constellations plotted by second century astronomer Ptolemy and remains today as one of the modern 88 constellations defined by the IAU (International Astronomical Union).
In Greek mythology, Aries represents the golden ram that was sent to rescue Phrixos and Helle, the children of King Athamus of Boeotia and his first wife Nephele. The King's second wife, Ino, was resentful and wanted the children, in particular, Phrixos killed. She induced a famine in the Kingdom and then falsified a message to the King, indicating Phrixos must be sacrificed in order to save the land. Athamus was about to sacrifice his son, when Aries - sent by Nephele - arrived. The ram managed to rescue Phrixos, but Helle didn't survive. Phrixus then sacrificed the ram to Zeus with its Golden Fleece presented to King Aeëtes of Colchis. In a later myth, Jason and the Argonauts who actively sought the fleece eventually managed to steal it. In ancient Egyptian astronomy, Aries was associated with the god Amon-Ra, who was depicted as a man with a ram's head and represented fertility and creativity. The Arabs knew Aries as a sheep and the Chinese as a dog.
The constellation contains a single second magnitude star, one third magnitude star, three fourth magnitude stars and over a dozen fifth magnitude stars. It contains no Messier objects and no bright deep sky objects. However, its boundaries contain numerous faint galaxies within the range of medium / large size amateur scopes. For small scopes, there are a handful of nice double stars, including some bright ones.
Two thousand or so years ago Aries contained the vernal equinox, the point where the Sun annually passes from south to north across the celestial equator. This occurs on or about March 20th and signals the start of spring in the Northern Hemisphere and autumn in the Southern Hemisphere. Due to precession the vernal equinox has now moved into neighbouring Pisces.
Aries covers 441 square degrees of sky, ranking it 39th in overall size. It's best seen from Northern Hemisphere locations during the months of October, November and December. There are several meteor showers that radiate from Aries, including the Daytime Arietids and the Delta Arietids.
NGC 2261 is a curious reflection nebula in Monoceros that's known as Hubble's Variable Nebula. It was discovered by William Herschel in 1783 and is illuminated by variable star R Monocerotis (R Mon). The nebula is unusual in that it changes shape over a period of just days and can vary by up to 2 magnitudes in brightness. The variations are believed to be due to periodic changes in the amount of dust surrounding R Mon, thus affecting the amount of light that reaches us. With an apparent magnitude of +9.0, it can be spotted with binoculars under dark skies.
The variability of R Mon (between magnitudes +10 and +12) was discovered at the Athens Observatory in 1861, but it wasn't until 1916 when Edwin Hubble realised that the nebula also changes in brightness. The variations are such that even on images taken only days apart, structural changes can be seen.
NGC 2261 was chosen as the "first light" photograph on January 26, 1949 for the 200-inch (5.1 m) Hale reflecting telescope under the direction of American astronomer Edwin Powell Hubble. At the time, the newly constructed Hale telescope was the largest telescope in the world and remained so until 1976. NGC 2261 is number 46 in the Caldwell catalogue.
NGC 4755, also known as the Jewel Box or Kappa Crucis Cluster, is one of the finest open clusters in the sky. It's located in the small southern constellation of Crux and at magnitude +4.2 is bright enough to be seen with the naked eye. It contains over 100 stars, mostly blue or red, spread over 10 arc minutes of apparent sky. This cluster is one of a handful of night time objects that offers something for all observers of all telescope sizes.
NGC 4755 is located 6,440 light-years distant and is best seen from southern latitudes during the months of March, April and May. It's circumpolar from locations south of 30S and can also be seen from the tropics, although for many Northern Hemisphere observers it never rises above the southern horizon.
NGC 891 is a tenth magnitude unbarred spiral galaxy located in Andromeda. Also known as the Silver Sliver, it's one of the best examples of an edge-on galaxy in the sky although a challenging object for small scopes. Due to its attractiveness and scientific appeal, NGC 891 was selected on October 12, 2005 to be the first light image of the Large Binocular Telescope at Mount Graham International Observatory in Arizona. In 2012, it was again selected as first light image, this time for the Discovery Channel Telescope (DCT) Large Monolithic Imager at the Lowell Observatory in Happy Jack, Arizona.
The Silver Sliver was discovered by William Herschel on October 6, 1784 and is best seen from the Northern Hemisphere during October, November and December. Astronomers think our Milky Way galaxy would look remarkably similar, if viewed edge-on.
Finder Chart for NGC 891 - pdf format (credit:- freestarcharts)
The Silver Sliver is located in eastern Andromeda close to the Perseus border. It's positioned 3.5 degrees east of beautiful double star Almach (γ And - mag. +2.1) with naked-eye open cluster M34 (mag. +5.5) a further 3.5 degrees to the east.
Vega is a brilliant magnitude +0.03 blue-tinged white main sequence star located in the constellation of Lyra. It's marginally brighter than Capella and slightly fainter than Arcturus, making it the second brightest star in the northern section of sky. With a declination of 38 degrees north, Vega appears high in the sky and sometimes overhead from many northern temperate locations. This star can be seen anywhere north of 51 degrees south and therefore is visible from the majority of the Southern Hemisphere, including all of Australia, New Zealand, South Africa and most of Argentina and Chile.
Vega is a dazzling beacon of light in the relatively faint, but prominent constellation of Lyra. It was originally named Wega from a derivative of the Arabic phrase "Al Nasr al Waqi" or Swooping Eagle. Around 12,000 BC, Vega was the North Pole star and it will once again return there around 13,700 AD. It's probably unsurprising, given its brilliance and prominent northern declination, that Vega is one of the most investigated stars. It was one of the first stars to have its distance determined by parallax, the first star other than the Sun to be photographed and the first to have its spectrum evaluated. Vega, along with Altair (α Aqr - mag. +0.77) and Deneb (α Cyg - mag +1.25), is a member of the well-known Summer Triangle. This bright asterism was popularised, in the 1950's, by American author H.A. Rey and British astronomer Sir Patrick Moore.
Vega is a class A0Va star that's positioned within the main sequence of the Hertzsprung-Russell diagram. It's a nearby star, only 25 light-years distant, and relatively young at 455 million years. This is about 1/10 the age of the Sun. However, Vega is burning through its hydrogen fuel at a fast rate and is expected to become an M class red giant in approx. 500 million years time. For comparison, the same scenario will not affect the Sun for another 5 billion years. Even though it's more than twice as massive and over 40 times more luminous than the Sun, Vega is still not large enough to explode as a supernova and will end its life, just like our star, as a white dwarf.
Canopus is a brilliant star in the southern constellation of Carina and the second brightest in the night sky. At magnitude -0.72, it's about half as bright as Sirius but appearances can be deceptive; Canopus is far the more powerful star and Sirius only appears brighter because it's much closer to us. With a declination of -52 degrees, Canopus is best seen from southern latitudes. It can appear high in the sky from Australia, New Zealand, South Africa and much of South America. Indeed from such locations, the star is either circumpolar or only sets briefly.
Canopus can't be seen from most of Europe and many parts of the United States. For observers north of 38 degrees latitude, it never rises above the horizon. However, those living in southern Spain, southern Portugal, southern Florida, southern Texas and Hawaii can glimpse the star during the winter months. It's also visible from India, Pakistan and much of China and Japan.
From a historical perspective, Canopus can be seen from Alexandria but not from Athens. This provided early proof that the Earth is a globe and not a flat disk.
NGC 3195 is a planetary nebula of mag. +11.5, located in the southern constellation of Chamaeleon. At a declination of -81 degrees, it's the closest bright planetary to the South Celestial Pole and therefore circumpolar from almost the entire Southern Hemisphere. Theoretically, it can also be seen from northern latitudes but only from south of +9 degrees. Even then, from such locations this planetary only scraps above the horizon and is an incredibly difficult, if not impossible, object to spot.
John Herschel discovered NGC 3195 on February 24, 1835. It's number 109 and the final object in the Caldwell catalogue.
NGC 4559 is a spiral galaxy located in the constellation Coma Berenices. At mag. +10.0 it can be spotted with binoculars, but is challenging, requiring dark skies and patience. However, its high surface brightness does somewhat help. The galaxy is a nice telescope target that offers something for all sizes of backyard instruments.
NGC 4559 was discovered by William Herschel on April 11, 1785 and is estimated to be 30 million light-years distant. It's best seen from northern locations during the months of March, April and May.