24-10-12. UNITAT 2.

UNIT 2. THE UNIVERS 

In this class we started the unit 2 of the univers. We made a previous evaluation of unit pointing the questions that we believe could answer in this unit. Then, we talked about the history of astronomy explaining calendars and constellations. And finally, we called and explained two scientifics, Eratosthenes of cryne, and Ptolomy.

      1. The history of astronomy
The astronomy tries to describe what’s in the sky.

   Calendars were one of the main applicatons of ancient astronomy. They were base don the motion of the moon (weeks) and sun (year) and allow to predict the seconds and the other natural phenoma.
They were developed to help manage crop growth and to determinate when to hold rituals.
[Mayan calendar was one of the first calendars (4000 BC).
Stonehenge calendar is a macro calendar. It was one of the first. It’s a group of stones. (2000 BC)] 

Stonehenge calendar

Mayan calendar

   Constellations are a group of stars that occupy a part of the celestial sphere.
Ancient astronomy imagined lines and draw connecting the stars and give natural or mithological names to those groups.
Actual constellations in northern hemisphere come from old Babilonia and Greek astrology.

      Eratosthenes of cyrene:
- Mesures the circumference of the Earth
- Said that the Earth is round! 

      Ptolomy:
- Catalog of 44 constellations
- Geocentric Universe
- Said that the Earth is at the center of the Universe
- Orbits and retrograda motion of the planets were explained through epicycles.