Summary
- The ancient solar system consists of…
- a night sky filled with hundreds of fixed stars that…
- remain in the same positions relative to one another
- appear to belong to groups called constellations named after supernatural beings
- rotate as a group across the sky about once every day
- shift gradually in the sky when viewed at the same time from night to night
- return to their original positions relative to the horizon after one year
- two primary moving objects…
- Sun
- moves across the sky once every day
- moves across the background of the fixed stars once every year
- Moon
- moves across the sky about once a every day
- cycles through visible changes (called phases) roughly once every month
- five planets visible to the unaided eye…
- named in English after gods of Ancient Rome
- Mercury
- Venus
- Mars
- Jupiter
- Saturn
- wander across the background sky of fixed stars
- Generally moving in the same direction as the Sun, Moon, and stars
- but occasionally moving backward (retrograde)
- a total of seven moving objects each of which is associated with a day of the week in English and other languages
