nLab Milky Way

Idea

Our galaxy.

Democritus $[$holds$]$ that it is the splendor which ariseth from the coalition of many small stars, which, being firmly united amongst themselves, do mutually enlighten one another.

Δημόκριτος πολλῶν καὶ μικρῶν καὶ συνεχῶν ἀστέρων συμφωτιζομένων ἀλλήλοις συναυγασμὸν διὰ τὴν πύκνωσιν.

(Pseudo Plutarch ~ 400 AD, attributing to Democritus $\sim$ 400 BC – original Greek here)

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The Milky Way is made up of a very large number of small, tightly-clustered stars, which, on account of their concentration and smallness, seem to be cloudy patches. Because of this, it was likened to milk in color.

(Naṣīr al-Dīn al-Ṭūsī in Tadhkira 1261 AD, as translated in Ragep 1993, p. 128)

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the Galaxy [Milky Way] is nothing else than a congeries of innumerable stars distributed in clusters. To whatever region of it you direct your spyglass, an immense number of stars immediately offer themselves to view, of which very many appear rather large and very conspicuous but the multitude of small ones is truly unfathomable.

(Galileo Galilei in Sidereus Nuncius 1610, as translated in Van Helder 1989, p. 34)

Related concepts

• astronomy, galaxy

• cosmology, observable universe

References

In antiquity and the middle ages:

• Pseudo-Plutarch, Of the Galaxy, or the Milky Way, Book 3, Chapter I in: Placita Philosophorum, ~300-400 AD

• F. J. Ragep, II.4 $[10]$ (p. 128) in: Naṣīr al-Dīn al-Ṭūsī’s Memoir on Astronomy (al-Tadhkira fī cilm al-hay’a): Volume I: Introduction, Edition, and Translation, Sources in the History of Mathematics and Physical Sciences 12, Springer 1993 (doi:10.1007/978-1-4757-2241-3)

• Albert Van Helden, Sidereal Messenger, translation of: Galileo Galilei, Sidereus Nuncius 1610, University of Chicago Press 1989 (pdf)

Modern survey

• Susan Gardner, Samuel D. McDermott, Brian Yanny, The Milky Way, Coming into Focus: Precision Astrometry Probes its Evolution, and its Dark Matter (arXiv:2106.13284)

See also

• Wikipedia, Milky Way