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SW214°
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🌟ByulGil
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Seoul
37°33′N · 126°58′E
2026.10.22 18:51
LIVE · 24 OF 40 ABOVE
Tonight's Sky
40 CONSTELLATIONS
constellation

Cepheus

세페우스자리
The pentagonal king · The King
Circumpolar · low in the north at night in May
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Science
The science

Cepheus is shaped like a five-sided "house" topped with a steep roof, a circumpolar constellation that wheels near the North Star all year round. Its Delta star (Delta Cephei) is a star that changed all of astronomy. It is a "pulsating variable" whose brightness rises and falls in a regular cycle of 5.4 days, and when Henrietta Leavitt discovered early in the 20th century the law that "the longer such a star's cycle, the truly brighter it is," Cepheids became the "standard candles" for measuring distances to galaxies. It was thanks to these very Cepheid variables that Hubble proved Andromeda to be another galaxy beyond our own Milky Way.

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Mythology
The myth

Cepheus was the king of ancient Ethiopia, husband of Queen Cassiopeia and father of Princess Andromeda. When the queen's boast that her daughter's beauty outshone the sea nymphs brought a sea monster's threat upon the kingdom, an oracle made the cruel demand that Andromeda be offered as a sacrifice. The king who loved his daughter fell into despair, but to save his kingdom he had at last to bind her to a seaside rock. Later, when the hero Perseus rescued Andromeda, Cepheus and his whole family became constellations set side by side in the autumn sky.

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Stars
Main stars (equatorial)
AlderaminRA 21.31h · Dec 62.6° · m2.5
AlfirkRA 21.48h · Dec 70.6° · m3.2
ErraiRA 23.66h · Dec 77.6° · m3.2
IotaRA 22.83h · Dec 66.2° · m3.5
ZetaRA 22.12h · Dec 58.2° · m3.4
DeltaRA 22.49h · Dec 58.4° · m4.1
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Ang mga konstelasyong nasa itaas ng iyong ulo ngayon ay nagbabago bawat sandali ayon sa oras, petsa, at kung nasaan ka. Habang umiikot ang Earth, sumisikat ang mga bituin sa silangan at lumulubog sa kanluran; habang umiikot ang Earth sa Araw, nagbabago ang mga konstelasyong nakikita ayon sa panahon. Kinakalkula ng Byulgil ang tunay na kalangitan mula sa datos ng astronomiyang J2000.0 at iginuguhit ang mga konstelasyong nakikita mula sa iyong lokasyon ngayon bilang isang live na mapa at sa AR. Walang kailangang i-install — buksan lang ang iyong browser at tingnan ang langit ngayong gabi.

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40 Kuwento ng Konstelasyon

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What is Byulgil?

Byulgil is a stargazing web app that computes the real night sky for your location, anywhere in the world, in real time. Byulgil means "Star Loads", in Korean. Use your current location (GPS) or pick a major city — Seoul, Tokyo, New York, Sydney — to see the sky exactly as it appears there, right now. Star positions come from real J2000.0 equatorial coordinates, converted to horizontal coordinates for your time and place. On mobile, AR mode lets you point your phone at the sky to overlay the constellations in that direction.