41 in-depth guides so far — starting with the brightest and most findable, each with a 3D star map you can explore.
What the constellations are
A constellation is one of the 88 official regions the sky is divided into — and, more loosely, the join-the-dots figure of bright stars that names it. The patterns are ancient, handed down from Greek, Babylonian and other traditions, but the modern list of 88 was fixed by the International Astronomical Union in 1922 and the exact boundaries between them approved a few years later, so today every star belongs to exactly one constellation. The shapes are a trick of perspective: the stars in a figure usually lie at wildly different distances and aren't related at all — they only line up as seen from Earth.
Why the evening sky changes with the seasons
As Earth orbits the Sun, our night side faces a different direction through the year, so the evening constellations slowly turn over — Orion rules winter evenings in the north, Scorpius the summer. Each night a given star rises about four minutes earlier, which adds up to a whole new set of evening constellations every couple of months. The ones near the pole are the exception: from mid-northern latitudes Ursa Major and Cassiopeia never set, circling Polaris all night, all year. Your latitude decides the rest — the far-southern Southern Cross never clears the horizon from most of the northern hemisphere, and much of Orion's southern neighbourhood stays hidden from far northern skies.
How to find them
The trick is to start from a shape you can already spot and star-hop to its neighbours. From the north, find the Big Dipper in Ursa Major and follow its two pointer stars to Polaris, or "arc to Arcturus" along the curve of its handle; in winter, Orion's belt points down to brilliant Sirius and up to orange Aldebaran. Each guide below walks the star-hops for one constellation, names its brightest stars, and says which season it's best seen — and the live sky map labels exactly what's overhead from your location right now.
Also in the sky (guides coming): Antlia, Apus, Ara, Caelum, Camelopardalis, Canes Venatici, Canis Minor, Chamaeleon, Circinus, Coma Berenices, Corona Australis, Corona Borealis, Crater, Dorado, Equuleus, Fornax, Grus, Horologium, Hydrus, Indus, Lacerta, Leo Minor, Lepus, Lupus, Lynx, Mensa, Microscopium, Monoceros, Musca, Norma, Octans, Pavo, Phoenix, Pictor, Piscis Austrinus, Pyxis, Reticulum, Sagitta, Sculptor, Scutum, Sextans, Telescopium, Triangulum, Tucana, Vela, Volans, Vulpecula.
More to explore: Meteor showers · Planets · Lunar eclipses