October

Tuesday 19 September 2017 - 23:01:59 Posted by  Bobby

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 The Night Skies of October

 The Andromeda Galaxy, M31, is almost over head for observers in the northern latitudes, although for those in the southern hemisphere it remains disappointingly low. There are few bright stars on display at this time of year, but the Great Square of Pegasus is easy to see from both hemispheres.

 Top 3 Constellations For October

 Cepheus (The King)

cepheus2

 Mythology of Cepheus

Cepheus is a far-northern constellation, adjoining Cassiopeia and extending almost to the north celestial pole, representing the mythical King Cepheus, the husband of the vain Queen Cassiopeia and father of Andromeda. Its brightest star is Alpha Cephei, of magnitude 2.5.

 The Facts

  • Depiction: The King
  • Pronounced: SEE-fee-us
  • Genitive: Cephei
  • Abbreviation: Cep
  • Highest in the Sky: September to October
  • Size Ranking: 27th
  • Coverage Area: 588 Sq. Degrees
  • Right Acension: 22 hours
  • Declination: 70°
  • Visibility: 90°N to 8°S

 Notable Objects

  • Delta Cephei: Variable star
  • Mu Cephei: Herschel's Garnet Star
  • NGC 40: Planetary nebula
  • NGC 188: Open cluster
  • NGC 6939: Open cluster
  • NGC 6946: Spiral galaxy
  • Struve 2873: Double star

 Named Stars

  • Alderamin, Alpha Cephei
  • Alfirk, Beta Cephei
  • Alrai, Gamma Cephei
  • Erakis (Garnet Star), Mu Cephei
  • Alkurhah, Xi Cephei
  • Alkalb, Rho Cephei

 Best Viewed Objects/Stars

Beta Cephei

 A double and variable star. The brighter component is a blue giant of magnitude 3.2, about 600 light-years away. It is a pulsating variable star (the prototype of a group called Beta Cephei stars), although its variations are so small that they are barely perceptible to the eye. A small telescope shows a companion of magnitude 7.9.

Delta Cephei

 A double star and a famous variable, is the prototype of so-called Cepheid variables, which astronomers use for finding distances in space. Such stars change in brightness as they pulsate in size. Delta Cephei itself varies between magnitudes 3.5 and 4.4 every 5 days 9 hours. It lies about 1,000 light-years away. A small telescope shows a wide companion of magnitude 6.3.

Mu Cephei (The Garnet Star)

 A variable star with a strong red color, hence its popular name, which is noticeable through binoculars or a small telescope. It is a red supergiant that pulsates in size, varying from magnitude 3.4 to 5.1 about every 2 years.

 Cassiopiea (The Queen)

cassiopeia2

 Mythology of Cassiopeia

 This attractive constellation represents the mythical Queen Cassiopeia. Her husband and daughter are represented by the adjacent constellations Cepheus and Andromeda. Cassiopeia was notoriously vain and is depicted sitting on a throne, fussing with her hair. Cassiopeia's brightest stars form a distinctive W-shape. Epsilon Cassiopeiae, at one end of the W, marks the queen's ankle while Beta, at the other end, lies in her shoulder.

 The Facts

  • Depiction: The Queen
  • Pronounced: kass-ee-oh-PEE-aah
  • Genitive: Cassiopeiae
  • Abbreviation: Cas
  • Highest in the Sky: October to December
  • Size Ranking: 25th
  • Coverage Area: 598 Sq. Degrees
  • Right Acension: 1 Hour
  • Declination: 60°
  • Visibility: 90°N to 21°S

 Notable Objects

  • M52: Open Cluster
  • NGC 281: Pac-Man Nebula
  • NGC 7789: Open cluster
  • NGC 457: ET Cluster
  • NGC 663: Open cluster
  • NGC 654: Open cluster
  • NGC 659: Open cluster

 Named Stars

  • Schedir, Alpha Cassiopeiae
  • Caph, Beta Cassiopeiae
  • Cih, Gamma Cassiopeiae
  • Ruchbah, Delta Cassiopeiae
  • Segin, Epsilon Cassiopeiae
  • Achird, Eta Cassiopeiae
  • Marfak, Theta Cassiopeiae
  • Marfak, Mu Cassiopeiae

 Best Viewed Objects/Stars

Gamma Cassiopeiae

 A variable star, currently about magnitude 2.2. Its rapid spin causes rings of gas to be thrown off its equator, changing its brightness temporarily.

Eta Cassiopeiae

 A double star. It consist of a yellow star of magnitude 3.5 and an orange companion of magnitude 7.5 that can be seen with a small telescope. The two stars lie 19 light-years away, forming a genuine binary pair with an orbital period of 480 years.

Rho Cassiopeiae

 A highly luminous yellow supergiant. As a result of pulsations in its size, it varies between about 4th and 6th magnitudes in a cycle that lasts just under a year.

M52

 An open cluster. It is visible with binoculars, covering an area about one-third the apparent size of the full Moon, although a telescope is needed to show its individual stars. It lies 5,200 light-years away. A 5th magnitude star that appears to be a member of the cluster actually lies much closer to us.

NGC 457

 An elongated open cluster, about one-third the apparent size of the full Moon and visible through binoculars or a small telescope. The cluster's appearance has been compared to an owl, with its two brightest stars marking the owl's eyes. The brightest star is the 5th magnitude Phi Cassiopeiae, a luminous supergiant.

 Perseus (The Hero)

perseus2

 Mythology of Perseus

Perseus represents the mythological Greek hero who decapitated the fearsome Medusa, whose gaze could turn men to stone. On his way back from this exploit, Perseus rescued Andromeda from the jaws of a sea monster. In the sky, Perseus lies next to Andromeda and her mother, Cassiopea, forming part of a great tableau depicting this most famous of Greek myths. Perseus is represented by brandishing his sword in his right hand, marked by the twin star clusters NGC 869 and NGC 884, while in his left hand he holds the head of Medusa, marked by the star Beta Persei, better known as Algol. A rich part of the Milky Way runs through Perseus, making it an attractive constellation for binocular users.

 The Facts

  • Depiction: The Hero
  • Pronounced: PURR-see-us
  • Genitive: Persei
  • Abbreviation: Per
  • Highest in the Sky: November to December
  • Size Ranking: 24th
  • Coverage Area: 615 Sq. Degrees
  • Right Acension: 3 hours
  • Declination: 45°
  • Visibility: 90°N to 29°S

 Notable Objects

  • Double Cluster: Double open clusters
  • M34: Open cluster
  • M76: Cork Nebula
  • NGC 1499: California Nebula

 Named Stars

  • Mirfak, Alpha Persei
  • Algol, Beta Persei
  • Miram, Eta Persei
  • Misam, Kappa Persei
  • Menkib, Xi Persei
  • Atik, Omicron Persei

 Best Viewed Objects/Stars

Alpha Persei

 A yellow-white super giant of magnitude 1.8, the brightest star in the constellation. It is a prominent member of a large and loose cluster of stars known as Melotte 20, visible with binoculars, which lies about 600 light-years away.

Beta Persei (Algol)

 A famous eclipsing binary star consisting of a close pair of stars in orbit around each other. When the brighter star is eclipsing the fainter one, every 2 days and 21 hours, the magnitude drops from 2.1 to 3.4 for about 10 hours.

Rho Persei

 A variable red giant. Due to changes in size, it varies from magnitude 3.3 to 4.0 in a cycle lasting about 7 weeks.

M34

 An open cluster about 1,500 light-years away. It is visible with binoculars or a small telescope and appears about the same size as the full Moon. The cluster's brightest stars are of 7th magnitude.

NGC 869 and NGC 884 (The Double Cluster)

 Two open clusters just visible to the naked eye; an excellent sight through binoculars or a small telescope. Each cluster covers about the same area of sky as the full Moon.

 Features of Interest (September/October)

 Andromeda Galaxy

andromeda
 The most distant object visible to the naked eye is a spiral galaxy similar to our home galaxy. Also called the Andromeda galaxy, it can be seen with the naked eye in rural skies, but its full extent is better appreciated through binoculars. M31 is about 2.5 million light-years away, so the light by which we now see it left when mankind's ancestors still roamed the plains of Africa.

 NGC 869, NGC 884

ngc869
 Two open clusters known as the Double Cluster, mark the hand of Perseus. When seen with the naked eye, the pair resembles a knot that appears brighter than the surrounding Milky Way. They are easy to see through binoculars.

 The Great Square of Pegasus

pegasussquare
 The corners of this huge square are marked by three stars in Pegasus and one in Andromeda. Despite the figures considerable size (about 15 degrees to a side, large enough to enclose 900 full Moons, it contains few naked-eye stars.

 Meteor Shower Activity

October Meteor Showers
(The Orionids)
 Radiating from northern Orion, near the border with Gemini, the Orionids reach a peak of about 25 meteors an hour around October 21. Since this area of sky does not rise until late, the shower is best viewed after midnight. The Orionids are fast moving but faint. Like the Eta Aquarids of May, they are caused by dust from Halley's Comet.

 Also Visible This Month

 Where to?

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