looking toward
SSW211°
ALT 24° · FOV 93°
🌟ByulGil
observatory
Seoul
37°33′N · 126°58′E
2026.10.22 19:07
LIVE · 24 OF 40 ABOVE
Tonight's Sky
40 CONSTELLATIONS
constellation

Aquila

독수리자리
Altair · The Eagle
Summer · rises in the east around 9 p.m. in May
✦
Science
The science

The chief star Altair (the Cowherd Star) lies just 16.7 light-years from Earth, one of the nearest of all first-magnitude stars. Its most astonishing feature is its dizzying rotation: its equator spins at about 900,000 km per hour (100 times the Sun's rate). The centrifugal force leaves the star not round but squashed flat like a pumpkin, so that its equatorial diameter is a full 20% greater than its polar diameter. It was among the first stars to have its shape imaged directly. Intriguingly, the three stars that appear in a straight line are not truly close in space at all — Tarazed is a giant red star about 20 times farther away than Altair (some 380 light-years), merely lying in the same direction as seen from Earth, an "apparent alignment."

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Mythology
The myth

In East Asia, Altair is the well-known Cowherd Star. Having fallen in love with the Weaver Maid (Vega) across the Milky Way and neglected his work, he was cast to the far bank of the river by the Jade Emperor, and the two may meet only one day a year — the seventh night of the seventh lunar month — upon a bridge of magpies who join heads to span the river. Tarazed and Alshain, on either side of Altair, are said to be the two children the Cowherd carries with him, which is why the three stars always travel together in a line. In the West, it is the sacred eagle that bore Zeus's thunderbolts, carrying the beautiful youth Ganymede up to the heavens.

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Stars
Main stars (equatorial)
AltairRA 19.85h · Dec 8.9° · m0.8
AlshainRA 19.92h · Dec 6.4° · m3.7
TarazedRA 19.77h · Dec 10.6° · m2.7
ZetaRA 19.09h · Dec 13.9° · m3.0
ThetaRA 20.19h · Dec -0.8° · m3.2
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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.