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
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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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Созвездия над вами прямо сейчас

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Ночное небо в реальном времени

Карта созвездий ночного неба в реальном времени

Какие созвездия сейчас у вас над головой, меняется от мгновения к мгновению — в зависимости от времени, даты и вашего местоположения. Пока Земля вращается, звёзды восходят на востоке и заходят на западе; пока Земля обращается вокруг Солнца, видимые созвездия меняются с временами года. Byulgil вычисляет это реальное небо по астрономическим данным J2000.0 и рисует созвездия, видимые из вашего местоположения прямо сейчас, в виде живой карты и в режиме AR. Ничего не нужно устанавливать — просто откройте браузер и посмотрите на сегодняшнее небо.

Созвездия по временам года

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Constellation Stories

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Tap a constellation in the sky above to fly to it. Each one comes with the science modern astronomy has uncovered, alongside the myths people have written into those stars.

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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.