All-sky map
People project the stars in the sky onto a plane according to their positions on the celestial sphere, and draw a series of star maps. As early as around 705 AD, China had a "Dunhuang Star Map". This is one of the earliest star maps with the largest number of stars in the world. The star map of Suzhou stone carvings, drawn in 1247, is also one of the earliest and most complete star maps in China.
An accurate star map is a good helper for astronomers. Astronomers can rely on star maps to identify stars and find celestial bodies that have not been observed in the past, such as nova, supernova and comet that suddenly burst into light. Herschel discovered Uranus in 178 1 year, Adams and Le Ye Wei discovered Neptune in 1846, and Piazi discovered the first asteroid in 180 1 year, all of which contributed to the map.
A catalog is a "roster" of celestial bodies, which records the positions of stars, stars and other celestial bodies that can explain the identity of celestial bodies. The earliest catalogue in the world was Shi Shen, an astronomer of Wei State in the Warring States Period, who recorded the position of 12 1 star. In Europe, the earliest catalog compiled by Hipachus in the 2nd century BC recorded the position of the 1022 star.
Many famous astronomers in history devoted themselves to the compilation of catalogues. With the development of astronomy, the observed celestial bodies become more and more complex, and the types of catalogs become more diverse. Stars, nebulae and galaxies all have their own catalogs.