Asterisms of the Night Sky

Big Dipper

Ursa Major · 26° across · best in April

Also: Plough (UK), Saptarishi (India), Northern Dipper (China)

Seven stars of Ursa Major. The two stars at the end of the bowl, Dubhe and Merak, point to Polaris; Mizar and Alcor, in the handle, are a naked-eye double.

Little Dipper

Ursa Minor · 19° across · best in June

Polaris is the end of the handle. Only Polaris, Kochab and Pherkad are easy from a city; the rest of the dipper needs a dark sky.

Three Leaps of the Gazelle

Ursa Major · 31° across · best in April

Three pairs of stars under the Big Dipper's bowl, said in Arab tradition to be the hoofprints of a gazelle leaping away from the lion, Leo.

Orion's Belt

Orion · 3° across · best in January

Also: Three Kings, Three Marys

Mintaka, Alnilam and Alnitak, three blue supergiants in a straight line 3° long. The belt points northwest to Aldebaran and southeast to Sirius.

Orion's Sword

Orion · 1° across · best in January

A short line of stars hanging from the belt. Its middle "star" is the Orion Nebula, M42, a cloud of glowing gas 1,300 light-years away.

Southern Cross

Crux · 6° across · best in May

Also: Crux

The four bright stars of Crux, the smallest constellation. The long axis points to the south celestial pole; on national flags of Australia, New Zealand, Brazil and Samoa.

Northern Cross

Cygnus · 22° across · best in September

The body and wings of Cygnus, the Swan, laid along the summer Milky Way. Deneb tops the cross and Albireo, a gold-and-blue double star, sits at its foot.

Cassiopeia's W

Cassiopeia · 13° across · best in November

Five stars of Cassiopeia, on the opposite side of Polaris from the Big Dipper. It looks like a W or an M depending on where it stands as it circles Polaris.

Teapot

Sagittarius · 14° across · best in August

Eight stars of Sagittarius. The Milky Way rises from the spout like steam, toward the center of the galaxy just west of it.

Kite

Boötes · 23° across · best in June

The body of Boötes, with Arcturus, the brightest star north of the celestial equator, at the bottom. Follow the arc of the Big Dipper's handle to find it.

Great Square of Pegasus

Pegasus, Andromeda · 21° across · best in October

Four stars about 15° apart marking the body of Pegasus; the northeast corner, Alpheratz, belongs to Andromeda. Few stars are visible inside it, a good test of sky darkness.

Water Jar

Aquarius · 4° across · best in October

A small Y of four stars that forms the urn of Aquarius, the Water Bearer. The η Aquariid meteors radiate from beside it in May.

Diamond Cross

Carina · 10° across · best in March

A diamond of four stars in Carina, larger and fainter than the Southern Cross, with Miaplacidus at its southern point.

False Cross

Carina, Vela · 9° across · best in March

Two stars of Carina and two of Vela. It is larger than the Southern Cross and often mistaken for it, but its long axis does not point to the pole.

Southern Pointers

Centaurus · 4° across · best in May

Also: The Pointers

α and β Centauri, the third- and 11th-brightest stars. They point to the Southern Cross and tell it apart from the False Cross.

Fish Hook

Scorpius · 30° across · best in July

Also: Maui's Fish Hook

The curve of Scorpius from its claws through red Antares to the stinger. In Polynesian tradition it is the hook the demigod Maui used to pull up the islands.

Sickle

Leo · 15° across · best in April

A backward question mark that forms Leo's head and mane, with Regulus as the dot. The Leonid meteors radiate from it in November.

Winter Hexagon

Auriga, Taurus, Orion, Canis Major, Canis Minor, Gemini · 66° across · best in February

Also: Winter Circle

Six first-magnitude stars in six constellations: Capella, Aldebaran, Rigel, Sirius, Procyon and Pollux, with Betelgeuse inside. It spans about 65°, the largest asterism here.

Sail

Corvus · 8° across · best in May

Also: Spica's Spanker

The four brightest stars of Corvus. The top edge, Gienah to Algorab, points east to Spica, hence its other name.

Keystone

Hercules · 9° across · best in July

Four stars forming the body of Hercules. The globular cluster M13 lies a third of the way from η to ζ Her, visible in binoculars.

Lozenge

Draco · 6° across · best in July

Also: Dragon's Head

The head of Draco, a small diamond of stars north of Vega. Eltanin, its brightest star, passes directly overhead from about 51°N, the latitude of London.

Circlet of Pisces

Pisces · 7° across · best in November

A ring of seven fourth- and fifth-magnitude stars south of the Great Square, marking the western fish of Pisces. It needs a dark sky.

Winter Triangle

Orion, Canis Major, Canis Minor · 27° across · best in January

Betelgeuse, Sirius and Procyon, a nearly equilateral triangle about 25° on a side, with the faint winter Milky Way running through it.

Summer Triangle

Lyra, Cygnus, Aquila · 38° across · best in August

Vega, Deneb and Altair. Deneb looks faintest but is the most luminous by far: about 2,600 light-years away against 25 for Vega and 17 for Altair.

Spring Triangle

Boötes, Virgo, Leo · 35° across · best in June

Arcturus, Spica and Denebola. "Arc to Arcturus, speed on to Spica": follow the curve of the Big Dipper's handle to find the first two.

Job's Coffin

Delphinus · 3° across · best in September

The small diamond of Delphinus, the Dolphin, east of Altair. Its stars α and β are named Sualocin and Rotanev, the first and last names of an assistant at Palermo Observatory spelled backward.