Stars Worth Knowing

Other Stars Worth Knowing

by John P. Pratt
©2003 by John P. Pratt. All rights Reserved.

Besides the fifteen bright (first magnitude) stars which are listed on a separate web page, there are several other stars worth knowing by name, even though they are not the brightest stars in the sky.

Dimmer Stars Worth Knowing

Name Location What to Remember

Polaris (poe-LAIR-us) Little Bear The Pole Star, so-called because it is currently within 1° of the North Celestial Pole. A second magnitude Cepheid variable. It can be found by using the stars Dubhe and Merak, the "Pointer Stars" of the Big Dipper.

Mizar (MY-zar) Big Bear The star at the bend in the handle of the Big Dipper. This star is three kinds of double stars in one. First it makes an optical double star with Alcor (AL-kor), a faint blue star that most people can see very near it in a dark sky. It is also a fine visual binary visible in a small telescope. The primary of that pair is also the first spectroscopic double which was discovered.

Kochab (KOE-cab) Little Bear The four stars in the bowl of the Little Dipper are of 2nd, 3rd, 4th and 5th magnitude, so they form a nice set of measuring standards. Kochab is the brightest of them. The name means "star" in Arabic, being short for "al Kaukab ash-Shamali" meaning "North Star," which it was from 1500 B.C. to A.D. 300.

Thuban (THOO-ban) Draco This star is easily found because it is nearly midway between Mizar and Kochab. It served as the Pole Star in ancient Egypt. Drawing a circle through it, Polaris and Vega shows the path of the North Celestial Pole over its 26,000 year cycle.

Algol (AL-gol) Head of Medusa, in Perseus Known as "The Demon Star" (from Arabic "Ras al Ghul," whence our word "Ghoul" derives). It represented the decapitated head of the snake-haired Medusa, which Perseus is carrying in a pouch. It is an eclipsing binary which dims one full magnitude in brightness about every three days when the larger dimmer star obscures the brighter.

Alcyone (al-SYE-oh-nee) in the Pleiades (the Seven Sisters) in The Bull The brightest of the Seven Sisters. This group has had great significance to many nations around the globe. The other sisters names are Maia (MAY-yuh), Electra (e-LEK-truh), Merope (MEH-ro-pay), Taygeta (tay-IH-jee-tuh), Celeno (se-LEE-NOE) and Sterope (STER-raw-pay), being the daughters of Atlas (AT-lus) and Pleione (PLEE-yah-nee). They are a nearby open cluster of about a hundred blue stars which is 2° across, a spectacular sight in binoculars.

Bellatrix (bell-LAY-triks) Shoulder of Orion The name is Latin for "The Female Warrior", and it is sometimes called the Amazon Star.

Mintaka (min-TOK-a) Orion's Belt Meaning "Belt," it is the western star of Orion's belt. All three belt stars are type O-B supergiants, being about 30,000° surface temperature; and over 10,000 times the brightness of the sun. Mintaka is almost exactly on the celestial equator.

Dubhe (DUB-bee) Big Bear The "Pointer Star" of the Big Dipper which is nearest to Polaris. The name means "Bear" in Arabic. The other pointer star is named Merak (MEE-rak). Merak is part of the nearby star cluster that most of the Big Dipper stars are in, but Dubhe is not in the cluster.

Castor (KAS-ter) Twins The name both of the other Twin (along with Pollux) as well as the star representing his head. It is a beautiful close double star, the first binary star discovered (it requires a 6" telescope). It is really a triple star, each member of which is a spectroscopic binary, so there are at least six stars in the system.

Albireo (al-BIR-ee-oh) Cygnus Perhaps the most beautiful double star, having blue and gold components. Easy to separate in any telescope.

Caph (KAF) Cassiopeia The star on the right side of the "W" of Cassiopeia. It is almost exactly on the 0 hour line of right ascension, so it culminates at 0 hours sidereal time.

Delta Cephei (DEL-ta CEF-ee-eye) Cepheus The first Cepheid variable discovered, for which they are named. Cepheids pulsate in brightness, with the period being directly related to their intrinsic luminosity. It change in brightness by nearly a full magnitude in 5 days. It is also a beautiful double star in binoculars.

Mira (MY-ra) Cetus Its name meaning "Wonderful", this "Miracle Star" is a long term variable which changes from 3rd to 10th magnitude (barely visible in binoculars) in 330 days. Its luminosity changes between 1 and 10,000 times the brightness of the sun.

Almach (AL-mak) Andromeda One of the most beautiful double stars, having yellow-orange and blue-green components.

Mirfak (MIR-fak) Perseus The brightest star in Perseus is in the center of a beautiful field of stars as seen in binoculars. They are an "association" which is like a cluster, but so loosely bound that is not held together by gravity.

Cor Caroli (CORE CARE-oe-lye) Canes Venatici A lovely double star with yellow components which can be seen in a 2" telescope.

Sheliak (SHELL-yak) Lyra Also called Beta Lyrae, this star is one of the most interesting to astronomers. It is an eclipsing binary with a 13 day period, with a half-magnitude variation which can be observed visually by comparison to the star next to it. It has bright emission lines and is expelling matter so quickly that its orbital period is changing rapidly.

Eltanin (el-TAY-nin) Draco Meaning "the serpent" in Arabic, this star is the eye of the Dragon. It and the other four stars in the head make good standards for 2nd, 3rd, 4th and 5th magnitude stars. Eltanin is useful to know because it has right ascension of 18h, and is circumpolar for many, so it can be used to tell sidereal time.

Rasalgethe (raz-ul-JEE-thee) Hercules Meaning the "head of the kneeler," it is a beautiful orange and green binary star, but it requires at least an 8" telescope to resolve it. The dimmer member is again a spectroscopic binary. The brighter member is a red giant with variaries erratically in brightness from 3rd to 4th magnitude in 50-130 days. It is ejecting great quantities of mass which envelop the entire system.

Dimmer Stars Worth Knowing
Name	Location	What to Remember
Polaris (poe-LAIR-us)	Little Bear	The Pole Star, so-called because it is currently within 1° of the North Celestial Pole. A second magnitude Cepheid variable. It can be found by using the stars Dubhe and Merak, the "Pointer Stars" of the Big Dipper.
Mizar (MY-zar)	Big Bear	The star at the bend in the handle of the Big Dipper. This star is three kinds of double stars in one. First it makes an optical double star with Alcor (AL-kor), a faint blue star that most people can see very near it in a dark sky. It is also a fine visual binary visible in a small telescope. The primary of that pair is also the first spectroscopic double which was discovered.
Kochab (KOE-cab)	Little Bear	The four stars in the bowl of the Little Dipper are of 2nd, 3rd, 4th and 5th magnitude, so they form a nice set of measuring standards. Kochab is the brightest of them. The name means "star" in Arabic, being short for "al Kaukab ash-Shamali" meaning "North Star," which it was from 1500 B.C. to A.D. 300.
Thuban (THOO-ban)	Draco	This star is easily found because it is nearly midway between Mizar and Kochab. It served as the Pole Star in ancient Egypt. Drawing a circle through it, Polaris and Vega shows the path of the North Celestial Pole over its 26,000 year cycle.
Algol (AL-gol)	Head of Medusa, in Perseus	Known as "The Demon Star" (from Arabic "Ras al Ghul," whence our word "Ghoul" derives). It represented the decapitated head of the snake-haired Medusa, which Perseus is carrying in a pouch. It is an eclipsing binary which dims one full magnitude in brightness about every three days when the larger dimmer star obscures the brighter.
Alcyone (al-SYE-oh-nee)	in the Pleiades (the Seven Sisters) in The Bull	The brightest of the Seven Sisters. This group has had great significance to many nations around the globe. The other sisters names are Maia (MAY-yuh), Electra (e-LEK-truh), Merope (MEH-ro-pay), Taygeta (tay-IH-jee-tuh), Celeno (se-LEE-NOE) and Sterope (STER-raw-pay), being the daughters of Atlas (AT-lus) and Pleione (PLEE-yah-nee). They are a nearby open cluster of about a hundred blue stars which is 2° across, a spectacular sight in binoculars.
Bellatrix (bell-LAY-triks)	Shoulder of Orion	The name is Latin for "The Female Warrior", and it is sometimes called the Amazon Star.
Mintaka (min-TOK-a)	Orion's Belt	Meaning "Belt," it is the western star of Orion's belt. All three belt stars are type O-B supergiants, being about 30,000° surface temperature; and over 10,000 times the brightness of the sun. Mintaka is almost exactly on the celestial equator.
Dubhe (DUB-bee)	Big Bear	The "Pointer Star" of the Big Dipper which is nearest to Polaris. The name means "Bear" in Arabic. The other pointer star is named Merak (MEE-rak). Merak is part of the nearby star cluster that most of the Big Dipper stars are in, but Dubhe is not in the cluster.
Castor (KAS-ter)	Twins	The name both of the other Twin (along with Pollux) as well as the star representing his head. It is a beautiful close double star, the first binary star discovered (it requires a 6" telescope). It is really a triple star, each member of which is a spectroscopic binary, so there are at least six stars in the system.
Albireo (al-BIR-ee-oh)	Cygnus	Perhaps the most beautiful double star, having blue and gold components. Easy to separate in any telescope.
Caph (KAF)	Cassiopeia	The star on the right side of the "W" of Cassiopeia. It is almost exactly on the 0 hour line of right ascension, so it culminates at 0 hours sidereal time.
Delta Cephei (DEL-ta CEF-ee-eye)	Cepheus	The first Cepheid variable discovered, for which they are named. Cepheids pulsate in brightness, with the period being directly related to their intrinsic luminosity. It change in brightness by nearly a full magnitude in 5 days. It is also a beautiful double star in binoculars.
Mira (MY-ra)	Cetus	Its name meaning "Wonderful", this "Miracle Star" is a long term variable which changes from 3rd to 10th magnitude (barely visible in binoculars) in 330 days. Its luminosity changes between 1 and 10,000 times the brightness of the sun.
Almach (AL-mak)	Andromeda	One of the most beautiful double stars, having yellow-orange and blue-green components.
Mirfak (MIR-fak)	Perseus	The brightest star in Perseus is in the center of a beautiful field of stars as seen in binoculars. They are an "association" which is like a cluster, but so loosely bound that is not held together by gravity.
Cor Caroli (CORE CARE-oe-lye)	Canes Venatici	A lovely double star with yellow components which can be seen in a 2" telescope.
Sheliak (SHELL-yak)	Lyra	Also called Beta Lyrae, this star is one of the most interesting to astronomers. It is an eclipsing binary with a 13 day period, with a half-magnitude variation which can be observed visually by comparison to the star next to it. It has bright emission lines and is expelling matter so quickly that its orbital period is changing rapidly.
Eltanin (el-TAY-nin)	Draco	Meaning "the serpent" in Arabic, this star is the eye of the Dragon. It and the other four stars in the head make good standards for 2nd, 3rd, 4th and 5th magnitude stars. Eltanin is useful to know because it has right ascension of 18h, and is circumpolar for many, so it can be used to tell sidereal time.
Rasalgethe (raz-ul-JEE-thee)	Hercules	Meaning the "head of the kneeler," it is a beautiful orange and green binary star, but it requires at least an 8" telescope to resolve it. The dimmer member is again a spectroscopic binary. The brighter member is a red giant with variaries erratically in brightness from 3rd to 4th magnitude in 50-130 days. It is ejecting great quantities of mass which envelop the entire system.