88 Official IAU Constellations · Interactive Guide
An Interactive Guide to the Night Sky
The Basics
At their simplest, constellations are groups of stars that form recognizable patterns in the night sky. The word comes from the Latin constellatio — "set of stars" — but formally, a constellation is not just a pattern but a precisely defined region of sky, like a country on a map of the Earth. Every star belongs to exactly one of the 88 official constellations, even the faint ones with no name.
"I know that I am mortal by nature and ephemeral, but when I trace at my pleasure the windings of the stars, my feet no longer touch the earth, but I take my fill of ambrosia."
— Claudius Ptolemy, Almagest (c. 150 CE (AD)The stars within a constellation may look close together from Earth, but they are actually vast distances apart in three-dimensional space — some millions of light-years behind others. The patterns exist only from our particular vantage point in the galaxy.
Humans have been grouping stars into meaningful shapes for at least 40,000 years, using them as calendars, navigation tools, and storytelling devices. The 88 figures we use today trace their roots to ancient Mesopotamia and Greece — most were formally cataloged by the Greek astronomer Ptolemy in the 2nd century CE (AD). As European explorers charted the southern skies in the 16th and 17th centuries they added new figures, often named after scientific instruments like the Telescope. In 1930 the International Astronomical Union drew permanent boundaries around all 88, dividing the entire celestial sphere into a precise and universal map of the sky.
Not every famous star pattern is a constellation. An asterism is a recognizable group of stars — sometimes within a single constellation, sometimes spanning several — that isn't officially designated as a constellation in its own right. The Big Dipper, for example, is an asterism within Ursa Major. The Summer Triangle spans three separate constellations. Asterisms are often the patterns people learn first, because they're the most visually obvious — but the constellation is the region, not just the pattern.
Ancient Star Lore
Long before telescopes or textbooks, every civilization on Earth looked up and found meaning in the same stars — yet each saw something entirely different. From the river valleys of Mesopotamia to the open Pacific, the night sky was a mirror of culture, season, and belief.
The oldest astronomical tradition on Earth. Many Aboriginal Australian cultures looked not at the stars, but at the dark dust clouds within the Milky Way — "Dark Constellations." The most famous is Gugurmin, the Emu, whose head is formed by the Coalsack Nebula near the Southern Cross. As the Earth rotates, the Emu acts as a celestial calendar — when it appears to run along the horizon in early winter, it signals time to harvest emu eggs.
The Sumerians and Babylonians were among the first to chart the sky, recording star patterns on clay tablets as early as 3000 BCE (BC). They established the zodiac, tracked planetary movements, and pioneered celestial divination — reading the heavens for omens to guide kings and harvests. Their system was the direct ancestor of the Greek constellations, and through them, of every star map used today.
For ancient Egyptians, the stars were companions on the journey to the afterlife. Orion represented Osiris, god of the underworld, while Sirius was linked to Isis, his devoted wife. The Great Pyramids of Giza were aligned with Orion's Belt — gateways to guide the pharaoh's soul among the stars. The annual rising of Sirius also marked the flooding of the Nile and the start of the agricultural year.
Ancient Chinese astronomers viewed the sky as a celestial reflection of the Emperor's government. Divided into Three Enclosures and Twenty-Eight Mansions, the North Star represented the Emperor himself — motionless while the court revolved around him. Smaller asterisms depicted court officials, marketplaces, and imperial stables. Changes in the stars were believed to predict changes in the fate of the Empire.
Polynesian navigators crossed thousands of miles of open Pacific without instruments, guided entirely by the stars. Rather than connecting dots into figures, they memorized "star paths" — the rising and setting points of stars on the horizon — as a living compass. Skilled navigators could read stars, ocean swells, and wind together to cross from Hawaii to New Zealand with extraordinary precision, passing this knowledge down through generations without written records.
The Greek system transformed the stars into a celestial storybook of gods, heroes, and mythical beasts — codified by Ptolemy in the 2nd century. Constellations like Orion and Cassiopeia immortalized oral traditions and moral lessons. Their zodiac follows the path of the Sun through the Mediterranean seasons, linking sky to agriculture and religion. These figures remain the foundation of the 88 official constellations used today.
Read the full story →To the Inca of the Andes, the Milky Way was a Great River inhabited by animal spirits. The largest dark-cloud constellation is Yacana, the Llama, with Alpha and Beta Centauri as its glowing eyes. Legend says Yacana descends to Earth at midnight to drink from the oceans, preventing the world from flooding. Its appearance in the sky guided the timing of llama herding and breeding cycles.
In Aotearoa, the Pleiades are called Matariki. Their midwinter rising in the pre-dawn sky marks the beginning of the Māori New Year — a time for reflection, honoring the dead, and celebrating the harvest. The clarity of the stars at rising forecast the season: hazy stars meant a cold year, clear stars a warm and bountiful one. Matariki remains a living, celebrated tradition in New Zealand today.
Heroes, monsters, and royal families — frozen in the stars for eternity. Explore the full Greek story, the three paths to the stars, and Ptolemy's 48.
Explore the Greek sky →In 1922, the International Astronomical Union standardized the sky into 88 official constellations with fixed, permanent boundaries — uniting the world's astronomers under a single map. Yet the older stories live on, a reminder that the stars have always been humanity's shared inheritance.
— From the IAU constellation system, adopted 1930What's Inside
Our guide is designed to turn anyone into a seasoned stargazer — breaking down the complexity of the cosmos into digestible, interactive data.
Discover the mythology and meaning behind the names, from ancient legends of Great Hunters to the astronomers who first recorded them.
Start with the Greeks →Discover the hidden shapes (asterisms) within constellations — like Orion's Belt — then use our star-hopping guide to navigate from one to the next using bright signpost stars.
Every entry includes the best month to view, hemisphere visibility, and a difficulty level to help you progress from easy targets to celestial challenges. Each page also includes the official IAU star chart alongside deep-sky NOIR images.
Never miss a "shooting star" again. We track the specific meteor showers associated with each constellation, including their peak viewing months.
Access technical data including abbreviations, proper pronunciations, and official genitive names used by professional astronomers.
Get shown images of easier-to-recognise constellations to quickly learn how to identify them and discover their story.
Explore the App
Choose where you'd like to begin — browse the full catalogue, dive into a single constellation, or orient yourself with this month's night sky.
Every constellation detail page includes the official IAU star chart alongside deep-sky NOIR images — long-exposure telescope photographs that reveal the true depth, density, and structure of the region as no computer-generated map can.
Browse and filter all 88 constellations by hemisphere, difficulty, origin, best month, and more.
Browse →Deep-dive into any constellation — charts, NOIR images, mythology, pronunciation, and scientific data.
Example: Orion →Monthly star charts help you orient yourself and find what's visible tonight from mid-latitudes of the Northern Hemisphere.
Courtesy of What's Out Tonight? © Ken Graun Example: Ursa Major →Step-by-step star-hopping guide for the Northern Hemisphere — learn to navigate from one constellation to the next using bright signpost stars.
Open star-hopping guide →About & Credits
This app was created by Andy Felong, a mostly retired software engineer with more than 40 years of experience spanning development, IT, quality assurance, operations, and management. Andy's passion for astronomy began long before his career, but was profoundly deepened by his early work writing real-time imaging software for Voyager spacecraft at the Jet Propulsion Laboratory. He has since held senior technology leadership roles at Apple Computer, Oracle Corporation, and Walmart.com, and most recently served as Vice President of Engineering at Agile Mind, a STEM oriented educational software company. Andy is an active contributor to the Open Source community and maintains a personal website at andyfelong.com, where you can find some of his apps and open source projects. He is currently a member of the Martz-Kohl Observatory, where he serves on the Media and Public Relations team, and is exploring the new generation of “smart” telescopes.
This app is free to use for personal, educational, and non-commercial purposes. Please do not reproduce or redistribute without permission.
Constellation images are provided by NOIRLab (National Optical-Infrared Astronomy Research Laboratory) under a Creative Commons Attribution 4.0 International (CC BY 4.0) license; credit: NOIRLab/NSF/AURA/E. Slawik. Official star charts are produced by the IAU (International Astronomical Union) in collaboration with Sky & Telescope, also under CC BY 4.0; credit: IAU and Sky & Telescope. Sky chart PDFs are courtesy of What's Up Tonight. Additional sky views were created using Stellarium, a free open-source planetarium. All images are used for non-commercial and educational purposes only.
The cultural and historical content on this site draws on the following primary and secondary sources. Summaries are editorial in nature — written as accessible introductions rather than academic treatments — and are intended for educational and non-commercial use only.
The Stars and Sticks constellation figures are rendered programmatically from two open data sources:
Development Tools — This application was developed with assistance from Claude (Anthropic), an AI assistant used for code review, content organization, and testing support. All editorial decisions, design, data selection, and final implementation are the work of Andy Felong.
Cultural and mythological summaries are editorial in nature and intended as introductions only. They represent one interpretation among many and should not be taken as definitive academic treatments. Where traditions vary, a representative version has been chosen for clarity.
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