A real-time night sky map that computes the stars actually visible from your location.
Which constellations are above your head right now changes from moment to moment with the time, the date, and where you are. As Earth turns, the stars rise in the east and set in the west; as Earth orbits the Sun, the constellations on view shift with the seasons. Byulgil computes this real sky from J2000.0 astronomical data and draws the constellations visible from your location right now as a live map and in AR. No install needed — just open your browser and see tonight's sky.
Tap to see which season's constellations are up tonight.
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.
The great ladle of the northern sky, Ursa Major cradles the Big Dipper. It holds the five sibling stars, the six-star system at Mizar, and the myth of Callisto.
Read more →Leo, the king of the spring sky. It carries Regulus, its chief star riding the ecliptic, and the tale of the Nemean Lion slain by Heracles.
Read more →Boötes, the kite-shaped herdsman. Arcturus, the fourth-brightest star in the night sky and a red giant, leads the herdsman who drives the bear.
Read more →Virgo, the second-largest constellation on the ecliptic. It holds Spica, the ear of wheat, and the Virgo Cluster of some 1,300 galaxies.
Read more →Cassiopeia, the W-shaped signpost for finding the North Star. Here Tycho's nova blazed in 1572 and opened the door to modern astronomy.
Read more →Gemini, the twins of the two brothers Castor and Pollux. Here are the most spectacular Geminid meteor shower and the myth of undying brotherly love.
Read more →Orion, the hunter of the winter sky. This giant carries Betelgeuse, poised on the brink of a supernova, and the Orion Nebula, a cradle of stars.
Read more →Lyra, glowing with Vega. It is the pole star of 12,000 years hence, the lyre of Orpheus, and the Weaver Maid of the Qixi legend.
Read more →Cygnus, the swan flying over the Milky Way, the Northern Cross. Here are Cygnus X-1, the first black hole candidate, and the supergiant Deneb.
Read more →Aquila, glowing with Altair the Cowherd star. Here are a star flattened by dizzying rotation and the Cowherd of the Qixi legend.
Read more →Corvus, a small but crisp trapezoid. It holds the colliding Antennae Galaxies and the legend of the crow that Apollo turned black.
Read more →Cancer, the faintest constellation of the zodiac. It holds the Beehive Cluster (M44), visible to the naked eye, and the myth of the crab that aided the Hydra.
Read more →Scorpius, with the red heart Antares. Here are dazzling clusters toward the galactic center and the myth of the scorpion that felled Orion.
Read more →Taurus, holding the red eye Aldebaran and the Pleiades cluster. The bull into which Zeus transformed himself charges across the winter sky.
Read more →Canis Major, holding Sirius, the brightest star in the night sky. It is the faithful hunting dog that follows Orion.
Read more →The pentagon of Auriga and its sixth-brightest star, Capella. It is the inventor of the chariot, cradling a young goat in his arms.
Read more →The home of the Andromeda Galaxy, the farthest object visible to the naked eye. This is the tale of the princess nearly given to a monster.
Read more →Perseus the hero, holding the winking "Demon Star" Algol. The hero who beheaded Medusa became a constellation.
Read more →Sagittarius, aiming at the center of the Milky Way. Beyond the Teapot shape hides the supermassive black hole at the galactic center.
Read more →Aquarius, pouring water from the heavens. One of the oldest constellations of the zodiac, it is the beautiful youth who served drink to the gods.
Read more →Aries, once the starting point of the zodiac. The hide of the golden ram that rescued two children later became the goal of the Argonauts.
Read more →Ursa Minor, wearing the guiding North Star (Polaris) at the tip of its tail. Shaped like a little ladle, it is the compass of the night sky.
Read more →Draco, the great dragon coiling around the celestial pole. Here are Thuban, the pole star of 5,000 years ago, and the dragon that guarded the golden apples.
Read more →Pegasus, the winged horse that forms the "Great Square," the landmark of the autumn sky. It was born from the blood of Medusa.
Read more →Canis Minor, made of just two stars. Procyon, the eighth-brightest star, forms one vertex of the Winter Triangle.
Read more →Hercules, the fifth-largest constellation in the sky. This greatest of heroes holds the trapezoidal "Keystone" and the beautiful globular cluster M13.
Read more →Libra, the only zodiac constellation that is not a living thing. Once the claws of the scorpion, it is the "Scales of Justice."
Read more →Delphinus, the little dolphin leaping beside the Milky Way. With its dainty rhombus shape, it carries the tale of the dolphin that saved a musician.
Read more →Pisces, two fish tied to each other by a long ribbon. Its stars are faint, yet the "vernal equinox" that marks the start of spring now lies within this constellation.
Read more →Capricornus, the "sea-goat" with the upper body of a goat and the lower body of a fish. The smallest constellation of the zodiac, it carries the tale of the god Pan and his transformation.
Read more →Ophiuchus, gripping a great serpent in both hands. It is the "thirteenth constellation" the Sun truly passes through, and Asclepius, the god of medicine who raised the dead.
Read more →Cepheus, shaped like a five-sided house with a steep roof. Here lies the original of the "Cepheid" variable stars that became the measuring rod for cosmic distances.
Read more →Cetus, the fourth-largest constellation in the sky (the sea monster). It holds Mira, a remarkable variable star whose brightness changes hundreds of times over.
Read more →Centaurus, holding "Alpha Centauri," the nearest neighboring star to the Sun. It is another guise of Chiron, the wise half-man, half-horse.
Read more →Crux, the emblem of the southern sky — the smallest yet most famous constellation, the Southern Cross. It is the guide for finding the south celestial pole and the cross emblazoned on many national flags.
Read more →Hydra, the largest constellation of all, sprawling across a full quarter of the sky. It is the nine-headed monster Hydra that Heracles faced.
Read more →Corona Borealis, a crown of seven stars tracing a half-circle. Here are the "Blaze Star," which may one day suddenly flare, and the tale of a princess's wedding garland.
Read more →Triangulum, a slender triangle formed by three stars. It hides the spiral galaxy M33, one of the farthest objects visible to the naked eye.
Read more →Lepus, the hare crouching at the feet of Orion the hunter. It is the little hare of the winter sky, keeping low as the hunting dog (Canis Major) gives chase.
Read more →Eridanus, the river of the sky that begins at Orion's feet and winds down into the southern heavens. It is the river into which the boy who fell from the runaway chariot of the Sun plunged.
Read more →The neighbors of our Sun, wandering among the stars. Meet all nine worlds — from Mercury to Neptune, and on to Pluto — in pictures and stories.
Beyond our own Milky Way lie countless island universes. Tap a galaxy to see its shape and what it looks like.
Public observatories and astronomy centers around your location — plan a night under a darker sky.
On July nights the Summer Triangle climbs high overhead while the Milky Way streams along the southern horizon. Here is your guide to the must-see sights in this month's sky.
No telescope needed. With a dark sky and a few simple tricks, your naked eyes alone can reveal hundreds of stars and the Milky Way. Here are seven tips for beginners.
How bright are stars, and how do astronomers rate the magnitude of a star? A clear guide to the brightness of stars scale — from a first-magnitude star to the faintest — plus what a star's color reveals about its temperature.
A supernova is a colossal explosion in which a single star can outshine an entire galaxy. Discover how the glorious death of a massive star scatters the elements that go on to build new stars, new planets, and even our own bodies.
Mountains on the Moon, moons around Jupiter, the phases of Venus — with what he saw through his telescope, Galileo shook the age-old belief that "the Earth is the center of the universe." This is the story of the man who opened the door to modern science.
From the world's first telescope to Kepler's refractor, Newton's reflector, and on to Hubble and James Webb lofted into space. Let's follow, with diagrams, the path humankind has walked to see the universe ever farther and ever deeper.
How did people ever work out the distances to the Moon and the stars, which no ruler could ever reach? From the principle of "parallax" you can check with a single finger, to the annual parallax used to measure the distance to stars and the equation behind it — explained here with diagrams.
The Sun vanishing at midday, a full Moon staining blood-red — these are among the sky's most mysterious events. Why do solar and lunar eclipses happen, and why not every month? Let's follow the geometry of the shadows cast by the Sun, Earth, and Moon.
Some stars are red, others blue. A star's color is not mere appearance but an accurate thermometer that tells its surface temperature. This is the story of color and temperature, and of the spectral types used to classify the stars.
A black hole is an abyss of the cosmos from which not even light can escape. What makes a black hole, and how did we confirm they exist? This is that story — including how Stephen Hawking revealed that "even black holes shine."
Just how far are a light-year and an astronomical unit (AU)? Here we gather in one place the sizes, masses, speeds, and temperatures of the Earth, Sun, Moon, and our Milky Way — the reference numbers for talking about the cosmos.
Starting from the Big Dipper, follow the Spring Curve and the Spring Triangle and Leo, Boötes, and Virgo unfold in turn. Here is your guide to the quiet spring sky that opens up once winter's brilliance withdraws — and to the sea of galaxies beyond it.
From the Summer Triangle overhead to Scorpius and Sagittarius on the southern horizon, summer is the season when the Milky Way streams across the sky. Here is your journey through the summer sky — finding the stars of the Herdsman and the Weaver Girl and gazing into the heart of our galaxy.
Using the Great Square of Pegasus as your landmark, star-hop all the way to the Andromeda Galaxy, the most distant object visible to the naked eye. This is a journey through the autumn sky, where Cassiopeia and Perseus meet the myth of a royal family hung together among the stars.
At the heart of the most brilliant sky of the year — winter — stands Orion. Using Orion as your reference, trace the Winter Triangle and the Winter Hexagon, and enjoy the Orion Nebula and the Pleiades with the naked eye on this journey through the winter sky.
Before a telescope, reach for binoculars. Portable and wide-viewed, they're the best first instrument for beginners — here's how to choose and use a pair.
From the Quadrantids to the Geminids, here's a rundown of the year's major meteor showers with their peak dates and expected hourly rates (ZHR).
You don't need expensive gear to capture stars, the Milky Way, and the Moon — just a smartphone camera. Here's how to set up Pro mode and shoot the night sky.
Those hazy smudges in the night sky — how do clusters, nebulae, and galaxies actually differ? Here's how to tell deep-sky objects apart, with the story behind the Messier catalog.
The full moon always seems especially large and bright at Chuseok. Here's how the lunar calendar and Korea's seasonal festivals connect to the night sky, and the story behind the harvest moon.
What do the numbers on a star chart actually mean? Starting from the fact that the sky has its own version of latitude and longitude, here's how a star's coordinates translate into the direction you actually look.
Why are there so few stars in the city at night? Here's the Bortle scale that ranks how dark a sky is, plus practical ways to find a darker sky near you.
Why does the Moon change shape every night? Here are the eight stages from new moon to full moon, and the two different "months" you need to know for planning an observation.
Kepler overturned a 2,000-year-old belief in perfect circles and showed that planets trace ellipses instead. His three laws remain the foundation of orbital calculations to this day.
In an era when astronomers believed our galaxy was the whole universe, Hubble proved Andromeda was a separate galaxy and discovered that the universe itself is expanding. Here's his story, along with the space telescope that carries his name.
Are there planets beyond our Solar System? Since the first confirmed discovery in 1995, thousands of exoplanets have been found. Here's how they're detected, and what it would take for one to support life.
From dark blemishes on the Sun's surface to auroras painting the night sky — here's how solar activity, rising and falling on an 11-year cycle, affects Earth and our daily lives.
Trace the universe's expansion backward in time and you arrive at a single conclusion: 13.8 billion years ago, everything began in a hot, dense point. Here's the key evidence behind the Big Bang theory.
Launched in 1977, two small probes swept past the giant planets one by one on their way out of the Solar System. Here's the story of the Golden Record carrying humanity's greeting, and the journey that continues to this day.
Astronomer Carl Sagan translated a complex universe into poetic language anyone could understand. Here's the story behind the documentary "Cosmos" and the "Pale Blue Dot" photograph, and his way of holding science and wonder together.
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.