Tag Archives: Cepheus

Perseus (A Greek mythological hero)

PerseusCCThe constellation Perseus is located near several other constellations to which Perseus is related in Greek mythology: Cepheus, Andromeda, Pegasus, Cassiopeia, and Cetus. This constellation was one of the 48 constellations cataloged by 2nd century astronomer Ptolemy that remain among the 88 modern constellations. This easily spotted constellation is well placed high in the northern sky and best seen in January. It is found between Cassiopeia and the Pleiades, and Mirfak (Alpha Persei) is its brightest star Its most interesting star Algol (Beta Persei) is an eclipsing binary star. Its variable brightness, which is noticeable to the naked eye, decreases by over one degree of magnitude for about ten hours on a cycle time of just under three days. This star is also known as the Demon Star, because the ancients perceived its variability as an ominous sign. Also notable in this constellation is theNGC869NGC884 Double Cluster (NGC 869 and NGC 884), which are naked eye objects under very dark skies. Perseus is home to two Messier objects, M34 and M76, and to the Perseids meteor shower. This meteor shower, one of the most consistently prominent meteor showers each year, lasts from mid-July to late August, peaking between the 9th and 10th of August.
http://en.wikipedia.org/wiki/Perseus_(constellation)

606px-Perseus_IAU.svg
IAU Perseus chart, IAU and Sky & Telescope magazine (Roger Sinnott and Rick Fienberg), June 5, 2011.

© James R. Johnson, 2014.
jim@jrjohnson.net

Lacerta (The lizard)

Andromeda, LacertaLacerta, the lizard, is a northern hemisphere constellation that presents a slight “W” shape, and is hence sometimes referred to as “Little Cassiopeia.” It is nestled among five large and distinct constellations: Cepheus, Cygnus, Pegasus, Andromeda and Cassiopeia, and it can be found highest in the sky at nightfall in March. Most notable for telescope viewers is Roe 47, a multiple star system consisting of five gravitationally-bound components between 6th and 10th magnitude. While the brightest, 6th magnitude component can usually be seen with the unaided eye under very dark skies, a modest telescope is required to see all five components.
http://en.wikipedia.org/wiki/Lacerta

IAU Lacerta chart, IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg), June 5, 2011.
IAU Lacerta chart, IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg), June 5, 2011.

© James R. Johnson, 2014
jim@jrjohnson.net

Andromeda (Cassiopeia’s daughter)

Andromeda, CassiopeiaAndromeda, the mythological daughter of Cepheus and Cassiopeia, is located near these two constellations and among several other constellations representing the Perseus myth, to include Perseus, Pegasus, and Cetus. It is one of the 48 constellations cataloged by 2nd century astronomer Ptolemy that remain among the 88 modern constellations. It is found directly overhead at the zenith after sunset in December. Although Andromeda is not a very distinct constellation in light-polluted skies, most of its stars can be observed. It’s brightest star, Alpheratz (Alpha Andromeda), is shared with the constellation Pegasus, and marks one corner of the Great Square of Pegasus. Locate this constellation by starting with the north eastern most star of the Great Square of Pegasus, and find the remaining stars flowing north east from there.

The Andromeda Galaxy (M31), M31boboThe Milky Way’s closest galactic neighbor, is found in this constellation. M31 can be found with the unaided eye in the very darkest of dark skies, but can easily be found with a binocular or telescope under most adverse light pollution conditions. M31 and M110 are two of M31’s dwarf companion galaxies that can also be seen in most photographs of M31.
http://en.wikipedia.org/wiki/Andromeda_(constellation)

IAU Andromeda chart, IAU and Sky & Telescope magazine (Roger Sinnott and Rick Fienberg), June 4, 2011.
IAU Andromeda chart, IAU and Sky & Telescope magazine (Roger Sinnott and Rick Fienberg), June 4, 2011.

© James R. Johnson, 2014
jim@jrjohnson.net

Cassiopeia (A Greek mythological queen)

CassiopeiaCassiopeia is named after the vain Greek mythological queen of Aethiopia, the wife of Cepheus and the daughter of Andromeda. This constellation was one of the 48 constellations cataloged by the 2nd century astronomer Ptolemy that remain among the 88 modern constellations. This 25th-largest constellation appears as either a distinct “M” (fall and winter) or “W” (spring and summer) shaped asterism of bright stars that often catches the eye of novice observers who happen to gaze in the right direction. Although it is a northern circumpolar constellation that can be seen year round, it is found high above Polaris in December, which is when it is most easily viewed. This constellation is located opposite of the Big Dipper from Polaris, so try finding it by starting at the Big Dipper, and tracing a line northward (upward) through Polaris until reaching the first grouping of bright stars.

The Milky Way flows through Cassiopeia, and it contains two Messier objects, M52 and M103, both of which are open star clusters. It also contains numerous other NGC objects and two supernova remnants, including Tycho’s Star, a supernova recorded in 1572 by Tycho Brahe, and another remnant of a supernova that was seen 300 years ago. Interestingly, if our sun were observed from Alpha Centuari, our nearest solar neighbor 4 light-years away, it would appear to be located in Cassiopeia.
http://en.wikipedia.org/wiki/Cassiopeia_(constellation)

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IAU Cassiopeia chart, IAU and Sky & Telescope magazine (Roger Sinnott and Rick Fienberg), June 4, 2011.

© James R. Johnson, 2014
jim@jrjohnson.net

The Circumpolar Region of the Celestial Sphere

A circumpolar object (star, constellation, deep space object) is one that never sets below the horizon during the Earth’s daily rotation. Any point in the sky that has a declination (degrees of separation from the celestial equator) greater than the observer’s latitude (degrees of separation from the terrestrial equator) will never set below the horizon. If for some reason the Sun ceased to illuminate the sky, a circumpolar object could be seen to circle Polaris once in about every 24 hour period. Cepheus, for instance, is a circumpolar constellation that is oriented with the top of the house-like asterism nearest Polaris. In the September evening sky, Cepheus is high above Polaris, and the “house” appears to be upside down. Over the course of 24 hours, Cepheus will circle Polaris. In six hours, the “house” is horizontal with the top pointing west, in 12 hours it appears upright, but below Polaris, in 18 hours it appears vertical again, this time with the top pointing east. Six months from now in March, Cepheus’ orientation at dusk is the same upright appearance as Cepheus’ 12-hour position in September.

The circumpolar region of the celestial sphere is indicated on the annotated sky map below as the nearly circular region. Two points define this region, the north celestial pole, and the north point on the horizon. The north celestial pole is at the center of the region’s circular border, and all stars on the map circle around this central point as a result of the earth’s daily rotation about its axis. Stars near the pole make small tight circles around the pole, while those out near the drawn circle, but still within the circle, make wider sweeping circles. Those stars outside of the circle also circle the pole, but will dip below the the northern horizon, and are therefore not circumpolar stars.

Sky_Map_Celestial_Zones

© James R. Johnson, 2015.

Cepheus (The King of Aethiopia)

CepheusCCCepheus is named after the Greek mythological King of Aethiopia, who was also Queen Cassiopeia’s husband and Princess Andromeda’s father. This constellation was one of the 48 constellations cataloged by the 2nd century astronomer Ptolemy that remain among the 88 modern constellations. This 27th-largest constellation is a fairly bright and recognizable circumpolar constellation. It is a house-like asterism of fairly bright stars that can be easily found north and east of Polaris in September’s evening skies.

Cepheus is home to some interesting deep space objects. NGC 188 is the closest open star cluster to the north celestial pole, and the Fireworks Galaxy (NGC 6946) is a spiral galaxy in which nine supernova have been observed, more than in any other galaxy. Also, a quasar that is powered by a supermassive black hole is among the most powerful objects in the universe is located in Cepheus.
http://en.wikipedia.org/wiki/Cepheus_(constellation)

IAU Cepheus chart, IAU and Sky & Telescope magazine (Roger Sinnott and Frick Fienberg), June 5, 2011.
IAU Cepheus chart, IAU and Sky & Telescope magazine (Roger Sinnott and Frick Fienberg), June 5, 2011.

© James R. Johnson, 2014.
jim@jrjohnson.net

Cygnus (The swan)

Cygnus, LyraCygnus, the swan, is a bright and distinct northern constellations, and one of the 48 constellations cataloged by 2nd century astronomer Ptolemy.  It is located among Lyra, Hercules, Draco, Cepheus, Lacerta and Pegasus. Deneb (Alpha Cygni) is its brightest star, and a member of the Summer Triangle. Cygnus reaches its highest ascension in September. A gracefully flying swan can be  easily imagined while taking in this constellation. Cygnus is also known as the Northern Cross.

Cygnus lies on the Milky Way’s plane, and is thus filled with many deep space objects. Of these, two were cataloged by Charles Messier. M39 is an open cluster of about 30 stars in the north east corner of Cygnus, and M29 is a small open cluster near the crux of the Northern Cross. There are several named nebula, star clusters, and galaxies to include the Blinking Nebula (NGC 6826), the Rocking Horse cluster (NGC 6910), the Veil Nebula, the North America Nebula (NGC 7000), the Northern Coalsack nebula, the Soap Bubble nebula (PN G75.5+1.7), and the Fireworks galaxy.
http://en.wikipedia.org/wiki/Cygnus_(constellation)

IAU Cygnus chart, (IAU and Sky & Telescope magazine (Rober Sinnott & Rick Fienberg), June 5, 2011.
IAU Cygnus chart, (IAU and Sky & Telescope magazine (Rober Sinnott & Rick Fienberg), June 5, 2011.

© James R. Johnson, 2014.
jim@jrjohnson.net