Stars & constellations · Science & history
Cool Star Facts
Bright stars and the patterns people see in them: where to look, what you are looking at, and the stories told about them. Part of Cool Moon Facts.
What’s above me?
Choose a place and a time and the sky finder works out which bright stars and constellations should be up, which way to face and how high to look. It runs in your browser for any night from 2000 to 2050, and nothing you enter leaves it.
Featured
Sirius is the brightest star in the night sky and one of the closest: its light takes about 8.6 years to reach us. It belongs to Canis Major, the Great Dog, and NASA's headlines still call it the Dog Star.
Sirius: the guide · NASA Science, Astronomers Use Hubble to 'Weigh' Dog Star's Companion (2005) (opens in a new tab)
Polaris is the North Star: the star nearest the point that the northern sky turns around. Because it barely moves, it shows the direction of north at night to anyone in the Northern Hemisphere. It is not, despite its fame, a particularly bright star.
Polaris: the guide · NASA Science, Skywatching FAQ (2024) (opens in a new tab)
Vega is the brightest star in the small constellation Lyra, the Lyre, and the brightest corner of the Summer Triangle. It is 25 light-years away: the light you see left it about 25 years ago.
Vega: the guide · NASA JPL, Tiny Particles, So Far Away (PIA07218, 2005) (opens in a new tab)
Betelgeuse is the reddish star at Orion's shoulder: a red supergiant so large that, put in place of the Sun, its surface would reach beyond the orbit of Jupiter. In 2019 and 2020 it faded so much that people noticed with the naked eye.
Betelgeuse: the guide · Ian Ridpath, Star Tales: Orion (opens in a new tab)
Rigel marks Orion's foot. It is a blue-white supergiant and usually the brightest star in Orion, even though it carries the second Greek letter, beta.
Rigel: the guide · Jim Kaler, Rigel, STARS (University of Illinois) (opens in a new tab)
Arcturus is the brightest star north of the celestial equator, a warm orange star in Boötes, the herdsman. It is easy to find, it is moving faster across the sky than almost any other bright star, and it once turned on the lights of a World's Fair.
Arcturus: the guide · ESA, Hipparcos: The 50 Brightest Stars (opens in a new tab)
Capella is the brightest star in Auriga, the Charioteer, and the first-magnitude star nearest the north celestial pole. What looks like one yellowish star is two giant stars circling each other every 104 days.
Capella: the guide · Jim Kaler, Capella, STARS (University of Illinois) (opens in a new tab)
Antares is the reddish star at the heart of Scorpius, a red supergiant about 700 times the Sun's diameter. Its name compares it to Mars, and it is easy to see why.
Antares: the guide · ESO, Best Ever Image of a Star's Surface and Atmosphere (eso1726, 2017) (opens in a new tab)
Canopus is the second-brightest star in the night sky, in the southern constellation Carina. From much of the Northern Hemisphere it never rises at all, which is why many people have never heard of it.
Canopus: the guide · ESA, Hipparcos: The 50 Brightest Stars (opens in a new tab)
Alpha Centauri is the nearest star system to the Sun: three stars a little over four light-years away. To the naked eye the two bright ones merge into a single point, the third-brightest in the night sky.
Alpha Centauri: the guide · NASA Science, Our Nearest Celestial Neighbor? An Exotic 3-Star System (opens in a new tab)
Orion is one of the few star patterns almost anyone can pick out: a bright rectangle with three stars in a row across its middle. Red Betelgeuse marks his shoulder, blue-white Rigel his foot.
Orion: the guide · Ian Ridpath, Star Tales: Orion (opens in a new tab)
Ursa Major, the Great Bear, is the third-largest constellation. Its seven brightest stars, the Big Dipper or Plough, form only the bear's back and tail; the rest of the animal is made of fainter stars.
Ursa Major: the guide · Ian Ridpath, Star Tales: Ursa Major (opens in a new tab)
Ursa Minor, the Little Bear, holds Polaris at the tip of its tail. Its seven main stars make a smaller, fainter ladle, the Little Dipper, that turns around the pole all night.
Ursa Minor: the guide · Ian Ridpath, Star Tales: Ursa Minor (opens in a new tab)
Cassiopeia's five brightest stars make a W, or an M, depending on the time of night. From mid-northern latitudes the queen circles the pole and never sets.
Cassiopeia: the guide · Ian Ridpath, Star Tales: Cassiopeia (opens in a new tab)
Cygnus, the swan, flies down the Milky Way with its wings outstretched. Its brightest stars make a large cross, the Northern Cross, with Deneb at the top.
Cygnus: the guide · Ian Ridpath, Star Tales: Cygnus (opens in a new tab)
Lyra is small but easy to find, because it holds Vega, the fifth-brightest star. Beside Vega a little figure of fainter stars makes the frame of the lyre.
Lyra: the guide · Ian Ridpath, Star Tales: Lyra (opens in a new tab)
Scorpius really looks like its namesake: a curving line of stars ending in a raised sting, with red Antares at the heart. It lies on the Sun's yearly path, low in the south for northern observers and high overhead for southern ones.
Scorpius: the guide · Ian Ridpath, Star Tales: Scorpius (opens in a new tab)
Leo is one of the few constellations that looks like what it is named for: a crouching lion. Six stars in the shape of a sickle outline his head and chest, with bright Regulus at the bottom.
Leo: the guide · Ian Ridpath, Star Tales: Leo (opens in a new tab)
Taurus is the bull charging at Orion. Its face is a V of stars, the Hyades, with orange Aldebaran as the eye, and the Pleiades ride on its back.
Taurus: the guide · Ian Ridpath, Star Tales: Taurus (opens in a new tab)
Gemini is two parallel lines of stars, the twins, with their heads marked by two bright stars close together: Castor and Pollux.
Gemini: the guide · Ian Ridpath, Star Tales: Gemini (opens in a new tab)
Crux, the Southern Cross, is the smallest of all 88 constellations, and one of the most famous. Its four bright stars make a compact cross, with two brilliant Pointers beside it.
Crux: the guide · Ian Ridpath, Star Tales: Crux (opens in a new tab)
Centaurus is a large southern constellation that wraps around the Southern Cross. It holds two of the sky's standouts: Alpha Centauri, the nearest star system, and Omega Centauri, the brightest globular cluster.
Centaurus: the guide · Ian Ridpath, Star Tales: Centaurus (opens in a new tab)
Bright stars
Constellations
The International Astronomical Union divides the whole sky into 88 constellations, as regions with boundaries. The figures drawn between their stars are traditions, not part of the definition.
Asterisms
Asterisms are familiar patterns that are not constellations, like the Big Dipper, which is part of Ursa Major, and the Summer Triangle, which borrows one star from each of three.
Three ways to read the stars
This is the science and history. Star stories gathers what different peoples have seen in the same sky, tradition by tradition. Stars in astrology & myth is the symbolic reading: zodiac signs, fixed stars and the North Star, as interpretation rather than prediction.
Reading directions in the sky
Altitude is how high something is: 0° is the horizon, 90° straight overhead. A fist held at arm’s length covers about 10 degrees (opens in a new tab).
Azimuth is the compass direction, measured clockwise from true north: 0° north, 90° east, 180° south, 270° west. A phone compass may show magnetic north, which can differ from true north by several degrees or more depending on where you are.
This section covers selected bright stars and constellations. Planets are not included, so a very bright “star” that is not in the finder may well be a planet.