The ancients had no telescopes but they were aware of many astronomical phenomena that are observable with the naked eye. Today, we understand what causes these phenomena:
The Earth rotates on its axis once every 24 hours, causing the Sun, stars and planets to appear to rise in the East and set in the West daily.
The Earth revolves around the Sun once every ~365 days. This motion causes different parts of the celestial sphere, and hence different stars, to be visible at night at different times of the year.
The Moon revolves around the Earth once every ~28 days, causing the Moon's phases.
The planes of orbit lie almost - but not quite - in the equatorial planes of the major body. As viewed from Earth, therefore, the Sun, Moon and planets follow paths across the sky along the ecliptic.
When the Earth, Moon and Sun are all lined up perfectly, it is possible to see an eclipse.
You might want to check out the links to up-to-date information on what is visible this month in the night sky from Astronomy magazine or SKY Online .
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