Star catalogue facts for kids

Kids Encyclopedia Facts

A star catalogue is like a giant list of stars in space. It helps astronomers keep track of them. Instead of long, complicated names, many stars are known by their catalogue numbers. Over many years, people have created different star catalogues for various reasons.

Ancient people like the Babylonians, Greeks, Chinese, Persians, and Arabs all made their own star lists. Sometimes, these lists came with star charts, which are like maps of the night sky. Today, most modern catalogues are digital and can be downloaded from space agencies. The biggest one is being made from the Gaia spacecraft, and it already lists over a billion stars!

Star catalogues also tell us how faint a star is (its limiting magnitude) and how accurately its position is known.

Old Star Catalogues

Early Sky Watchers

The ancient Egyptians knew about some constellations and used lists of stars called "decans" as a kind of star clock. They called stars that never set "the star that cannot perish." Even though they didn't make formal star catalogues, they drew amazing star maps on coffins and tomb ceilings.

The very first star catalogues we know of were made by the ancient Babylonians in Mesopotamia around 1500-1155 BC. These lists, written on clay tablets, named 36 stars. They divided the sky into three parts, each with twelve stars. Later Babylonian lists, like the Mul.Apin, also showed star patterns similar to those the Greeks would use much later.

Greek and Roman Star Lists

In Ancient Greece, an astronomer named Eudoxus mapped out the classical constellations around 370 BC. His work, Phaenomena, became a very important text. It described where stars were and how constellations looked, and even when they would rise and set.

Later, in the 3rd century BC, Greek astronomers Timocharis of Alexandria and Aristillus created another star catalogue. Around 129 BC, Hipparchus made his own star catalogue, which was the first known attempt to map the entire sky. By comparing his work to Timocharis', he noticed that star positions had changed over time. This helped him figure out the first value for the precession of the equinoxes, which is a slow wobble of Earth's axis.

In the 2nd century AD, Ptolemy from Roman Egypt published his famous star catalogue in a book called Almagest. It listed 1,022 stars visible from Alexandria. Ptolemy's catalogue was mostly based on Hipparchus's work. It was the main star catalogue in the Western and Arab worlds for over 800 years! Later, the Islamic astronomer al-Sufi updated it in 964 AD, and Ulugh Beg redetermined star positions in 1437. But it wasn't fully replaced until Tycho Brahe's catalogue came out in 1598.

Ancient texts from India also showed a good understanding of star positions and constellations.

Chinese Star Records

The earliest Chinese star names were found on oracle bones from the Shang dynasty (around 1600-1050 BC). Later texts from the Zhou dynasty (around 1050-256 BC) also listed star names. The Lüshi Chunqiu (around 235 BC) gave names for most of the twenty-eight mansions, which were groups of stars along the path the Sun appears to take. A chest found in a tomb from 433 BC also had a complete list of these mansions.

Star catalogues are often linked to two Chinese astronomers, Shi Shen and Gan De, who might have lived in the 4th century BC. They focused on different constellations for astrological reasons.

During the Han dynasty (202 BC – 220 AD), astronomers started listing all the stars visible to the naked eye, not just those along the Sun's path. A catalogue in the Records of the Grand Historian by Sima Qian (145–86 BC) included about 90 constellations. Their stars were named after things like temples, markets, shops, and different people. Later, in 120 AD, the astronomer Zhang Heng created a catalogue with 124 constellations. Chinese constellation names were later used by Koreans and Japanese.

Islamic World's Contributions

Many star catalogues were created by Muslim astronomers during the Islamic Golden Age. These were often part of larger books called Zij treatises. Famous examples include Arzachel's Tables of Toledo (1087) and Ulugh Beg's Zij-i Sultani (1437).

Other important Arabic star catalogues include Alfraganus's A compendium of the science of stars (850), which corrected Ptolemy's Almagest. al-Sufi's Book of Fixed Stars (964) described stars' positions, brightness, and colour. It even had drawings for each constellation and was the first known description of the Andromeda Galaxy. Many stars still have names that come from Arabic!

Americas Before Columbus

The Motul Dictionary, written in the 16th century, contains a list of stars first observed by the ancient Mayas. The Maya Paris Codex also shows symbols for constellations, often represented by mythical creatures.

Bayer and Flamsteed's Systems

Two important ways of naming stars that started with old catalogues are still used today.

The first system came from the German astronomer Johann Bayer in 1603. He gave bright stars a Greek letter followed by the Latin name of their constellation. For example, Alpha Centauri or Gamma Cygni. The problem was that there are only 24 Greek letters, and some constellations have many bright stars. Bayer tried using Roman letters too, but most of those names didn't stick. However, his system was a starting point for how we name variable stars today.

The second system came from the English astronomer John Flamsteed in 1725. He also used the constellation name, but he used numbers instead of Greek letters. Examples include 61 Cygni and 47 Ursae Majoris.

Modern Full-Sky Catalogues

Bayer and Flamsteed's catalogues only listed a few thousand stars. Modern "full-sky" catalogues try to list every star brighter than a certain brightness. Since there are billions of stars, this means focusing on the brighter ones.

Lalande's Catalogue

Jérôme Lalande published the Histoire céleste française in 1801. It was a huge star catalogue with positions and brightness for 47,390 stars, up to magnitude 9. This was the most complete catalogue of its time. It was so accurate that observatories used it as a reference throughout the 1800s.

The Durchmusterung Catalogues

The Bonner Durchmusterung (which means "Bonn sampling" in German) and its follow-ups were the most complete star catalogues before photography was used.

The original Bonner Durchmusterung was published between 1852 and 1859. It listed 320,000 stars in the northern sky. Because it didn't cover the whole sky, it was later added to by:

The Südliche Durchmusterung (SD), covering stars further south.
The Cordoba Durchmusterung, which covered even more of the southern sky.
The Cape Photographic Durchmusterung, also covering southern stars.

Astronomers often prefer using the HD numbers (see next section) because that catalogue also gives information about a star's spectral type (what it's made of). But for stars not in the HD catalogue, they sometimes use these older "Durchmusterung" names.

Star names from these catalogues start with initials like BD, CD, or CP, followed by the star's declination (its angle north or south in the sky), and then a number. For example, BD+50°1725.

The Henry Draper Catalogue (HD/HDE)

The Henry Draper Catalogue was published from 1918 to 1924. It covers the entire sky down to about the ninth or tenth magnitude. It's special because it was the first large catalogue to list the spectral types of stars.

This catalogue was put together by Annie Jump Cannon and her team at Harvard College Observatory. It was named after Henry Draper, whose wife provided money for the project.

HD numbers are still widely used today for stars that don't have a Bayer or Flamsteed name. The numbers are given in order of right ascension (like longitude in the sky).

Guide Star Catalog (GSC)

The Guide Star Catalog is an online list of stars created to help the Hubble Space Telescope find and focus on objects. The first version, made in the late 1980s, had about 20 million stars. The newest version has information for over 945 million stars, down to magnitude 21! This catalogue is still used to help the Hubble Space Telescope point accurately.

Hipparcos Catalogue (HIP)

The Hipparcos catalogue was created using data from the European Space Agency's Hipparcos satellite, which worked from 1989 to 1993. The catalogue was released in 1997 and lists 118,218 stars. It's famous for its very accurate parallax measurements, which help astronomers figure out how far away stars are.

Gaia Catalogues

The Gaia catalogues are based on observations from the Gaia space telescope. These catalogues are released in stages, with more and more information each time. You can find all the data from Gaia at its online archive.

The first release (DR1) in 2016 had positions and brightness for 1.1 billion stars. The second release (DR2) in 2018 included positions, parallaxes, and proper motions for about 1.3 billion stars, plus information on their colors and how fast they move towards or away from us. It also had data for over 14,000 objects in our Solar System. The third release (DR3) in 2020 and 2022 provided even more accurate data for over 1.8 billion objects, including variable stars and quasars. The final Gaia catalogue will be released a few years after the mission ends.

Special Star Catalogues

Some catalogues don't try to list every star. Instead, they focus on specific types of stars, like stars that change brightness or stars close to Earth.

Double Star Catalogues

Aitken's double star catalogue (1932) lists 17,180 double stars in the northern sky. Friedrich Georg Wilhelm von Struve also discovered many double stars and published his catalogue in 1827. For example, the binary star 61 Cygni is also called "Struve 2758" or "STF 2758."

Nearby Star Catalogues (Gl, GJ, Wo)

The Gliese (and later Gliese-Jahreiß) catalogue tries to list all star systems within about 20-25 light-years of Earth. The numbers in this catalogue (like Gl 436 or GJ 436) help astronomers identify these nearby stars.

Proper Motion Catalogues

One way to find nearby stars is to look for stars that appear to move a lot across the sky over time. This is called proper motion. Several catalogues focus on these stars, including those by Ross, Wolf, and Willem Jacob Luyten.

Zodiacal Catalogue (ZC)

Robertson's Zodiacal Catalogue lists 3539 stars brighter than 9th magnitude that are in the zodiac (the path the Sun, Moon, and planets appear to follow). It's mainly used for studying star occultations by the Moon.

Images for kids

An illustration of the constellation Perseus (after Perseus from Greek mythology) from the star atlas published by the Polish astronomer Johannes Hevelius in 1690