Episode 308 – Northern Stars You Should Know With Dave Chapman Show Notes


Stars You Should Know

(Dave Chapman, 2023)

Coming up: 

Spring (May)

Summer (July)

Fall (September)

South Polar (November)

Focussing on classic Greek-Roman names with occasional indigenous references. The classic names are used in some GoTo telescope software for sky alignment (e.g. Sky-Watcher SynScan and Celestron).

Spectral classes O B A F G K M — Annie Jump Cannon

Stars You Should Know—North Polar

About 12 bright stars —from 2nd to 4th magnitude (OK to find, even in the city)

—4 are used for celestial navigation (58 in all)  

—the first 9 are Sky-Watcher SynScan and  Celestron alignment stars

Starting with Ursa Major—usually identified as the Big Dipper

—useful in finding the North Star (Polaris)

Consult a simple north polar star chart with Polaris in the centre.

URSA MAJOR (UMa) “Great Bear”

First 2 stars are the pointer stars, Dubhe & Merak

Dubhe – alpha UMa “Back of the Bear” 

– mag. 1.8, variable multiple star, K0 orange, classic navigation star

– with the other three “bowl” stars of the Big Dipper, represents the she-bear Muin 

– Muin and the Seven Bird Hunters (Mi’kmaq sky story)

Merak – beta UMa “Loins of the Bear”

– mag 2.3, variable star, A0 white

– Merak and Dubhe are The Pointers, about 5 degrees apart

Mizar – zeta Uma “Horse and Rider” (with Alcor)

– Middle star in handle

– mag. 2.2, multiple star, A1 white

– famous vision test for Roman soldiers, 12 minutes of arc apart

– Chickadee and birchbark pot in the Muin story

More info on the Mi’kmaw sky story Muin and Seven Bird Hunters: tinyrl.com/4akte5cy 

URSA MINOR (UMi) “Small Bear”

Polaris – alpha UMi “North Star” 

– use Ursa Major The Pointers Merak & Dubhe to find Polaris (Merak—>Dubhe, 6 times the  distance)

 – mag. 2.0, delta Cepheid variable double star, F7 yellow-orange, classic navigation                 star 

– NOT the brightest star in the sky (#49 on p. 283 of the Handbook)

– brightest star within 30 degrees of the north celestial pole 

– is getting brighter and its variability is decreasing

Kochab –    beta Umi the “Guardians of the Pole” with Pherkad (not IAU) (Like Merak &  Thuban of Umi)

  • mag. 2.1, variable double star, K4 orange giant, classic navigation star
  • 500 times more luminous than Sun, 50 times bigger

CASSIOPEIA (Cas) “Queen of (Ancient) Ethiopia”

Follow a line from Mizar through Polaris and beyond to find the W shape.

Schedar – alpha Cas “Breast”

  • mag. 2.2, multiple  star, K0 orange, classic navigation star

Caph – beta Cas “Stained Hand”

  • mag. 2.3, variable double star, F2 yellow-white giant
  • varies 6% in brightness over 2.5 hour period

Navi – gamma Cas (not IAU)

  • reverse spelling of “Ivan,” middle name of astronaut Gus Grissom
  • mag. 2.2, variable double star, B0 blue-white
  • Be star—rapidly rotating, 150x the Sun

DRACO (Dra) “Dragon” (guarded the Golden Fleece)

Eltanin – gamma Dra “Serpent” or “Dragon”

  • mag. 2.2, double star, K5 orange-red, classic navigation star (brightest in Draco)
  • moving towards Earth, may be brightest star in sky in 1.5 million years

Thuban – alpha Dra “Dragon’s Tail”

  • midway between Mizar and Kochab
  • mag. 3.7, variable double star, A0 white giant—may have been brighter
  • was pole star when Egyptians built pyramids

CEPHEUS (Cep) “King of (Ancient) Ethiopia”

delta Cep – no name (not bright enough?)

  • mag. 3.5, delta Cepheid variable/double star, F5–G2 yellow supergiant
  • Henrietta Swan Leavitt discover the yardstick of the heavens: regular period correlated with absolute magnitude
  • Led to determining the distance to M31 and unlocking one of the greatest mysteries of the universe

mu Cep – Herschel’s “Garnet Star” (not IAU)

  • mag. 3.4–5.1 variable double star, M2 supergiant
  • multiple star system of 6 components
  • very large (out to Jupiter/Saturn distance) very luminous, abs. mag. -7

only dim because of large distance ~2400 light years

  • mu Cepheid irregular variable, like Betelgeuse, will probably become supernova 
  • deep red colour in telescope 


Star Tales (2018) Ian Ridpath

Star Names (1963) Richard Hinckley Allen

Sky Safari 7 Pro (star lore by Jim Kaler)

A Concise Dictionary of Astronomy (1991) Jacqueline MItton

RASC Observer’s Handbook (2023)

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