Timeline of knowledge about galaxies, clusters of galaxies, and large-scale structure
The following is a timeline of galaxies, clusters of galaxies, and large-scale structure of the universe. 5th century BC — Democritus proposes that the bright band in the night sky known as the Milky Way might consist of stars. 4th century BC — Aristotle believes the Milky Way to be caused by "the ignition of the fiery exhalation of some stars which were large, numerous and close together" and that the "ignition takes place in the upper part of the atmosphere, in the region of the world which is continuous with the heavenly motions". 964 — Abd al-Rahman al-Sufi (Azophi), a Persian astronomer, makes the first recorded observations of the Andromeda Galaxy and the Large Magellanic Cloud in his Book of Fixed Stars, and which are the first galaxies other than the Milky Way to be observed from Earth. 11th century — Al-Biruni, another Persian astronomer, describes the Milky Way galaxy as a collection of numerous nebulous stars. 11th century — Alhazen (Ibn al-Haytham), an Arabian astronomer, refutes Aristotle's theory on the Milky Way by making the first attempt at observing and measuring the Milky Way's parallax. and he thus "determined that because the Milky Way had no parallax, it was very remote from the Earth and did not belong to the atmosphere". 12th century — Avempace (Ibn Bajjah) of Islamic Spain proposes the Milky Way to be made up of many stars but that it appears to be a continuous image due to the effect of refraction in the Earth's atmosphere. 14th century — Ibn Qayyim al-Jawziyya of Syria proposes the Milky Way galaxy to be "a myriad of tiny stars packed together in the sphere of the fixed stars" and that these stars are larger than planets. 1521 — Ferdinand Magellan observes the Magellanic Clouds during his circumnavigating expedition. 1610 — Galileo Galilei uses a telescope to determine that the bright band on the sky, the "Milky Way", is composed of many faint stars. 1612 — Simon Marius using a moderate telescope observes Andromeda and describes as a "flame seen through horn".
