The document traces key developments in human understanding of the cosmos from ancient times to the present. [1] Early Greek astronomers like Aristarchus and Eratosthenes made some of the first estimates of distances to celestial objects using observations and simple geometry. [2] Over centuries, improved observations and mathematical proofs allowed astronomers like Ibn al-Shatir and Tycho Brahe to refine estimates of distances within our solar system and to the sun. [3] In the 18th-19th centuries, astronomers like Herschel, Bessel and Hubble made breakthrough discoveries that revealed the vast scale of our Milky Way galaxy and that other galaxies exist far beyond it, establishing the modern scale of the observable universe at billions of