courtesy  : wikipedia

the exploration of moon

The ancient Greek philosopher Anaxagoras (d. 428 BC) reasoned that the Sun and Moon were both giant spherical rocks, and that the latter reflected the light of the former. His non-religious view of the heavens was one cause for his imprisonment and eventual exile.^[1] In his book On the Face in the Moon’s Orb, Plutarch suggested that the Moon had deep recesses in which the light of the Sun did not reach and that the spots are nothing but the shadows of rivers or deep chasms. He also entertained the possibility that the Moon was inhabited. Aristarchus went a step further and computed the distance from Earth, together with its size, obtaining a value of 20 times the Earth radius for the distance (the real value is 60; the Earth radius was roughly known since Eratosthenes).

Although the Chinese of the Han Dynasty (202 BC–202 AD) believed the Moon to be energy equated to qi, their ‘radiating influence’ theory recognized that the light of the Moon was merely a reflection of the Sun (mentioned by Anaxagoras above).^[2] This was supported by mainstream thinkers such as Jing Fang,^[2] who noted the sphericity of the Moon.^[2] Shen Kuo (1031–1095) of the Song Dynasty (960–1279) created an allegory equating the waxing and waning of the Moon to a round ball of reflective silver that, when doused with white powder and viewed from the side, would appear to be a crescent.^[2]

By 499 AD, the Indian astronomer Aryabhata mentioned in his Aryabhatiya that reflected sunlight is what causes the Moon to shine.^[3]

Habash al-Hasib al-Marwazi, a Persian astronomer, conducted various observations at the Al-Shammisiyyah observatory in Baghdad between 825 and 835 AD.^[4] Using these observations, he estimated the Moon’s diameter as 3,037 km (equivalent to 1,519 km radius) and its distance from the Earth as 346,345 km (215,209 mi).^[4] In the 11th century, the Islamic physicist Alhazen investigated moonlight through a number of experiments and observations, concluding it was a combination of the moon’s own light and the moon’s ability to absorb and emit sunlight.^[5][6]

By the Middle Ages, before the invention of the telescope, an increasing number of people began to recognise the Moon as a sphere, though many believed that it was “perfectly smooth”.^[7] In 1609, Galileo Galilei drew one of the first telescopic drawings of the Moon in his book Sidereus Nuncius and noted that it was not smooth but had mountains and craters. Later in the 17th century, Giovanni Battista Riccioli and Francesco Maria Grimaldi drew a map of the Moon and gave many craters the names they still have today. On maps, the dark parts of the Moon’s surface were called maria (singular mare) or seas, and the light parts were called terrae or continents.