An Introduction to Astronomy The Electromagnetic Spectrum and Greco-Roman Times

The Electromagnetic Spectrum ow_l1/emspectrum.html ow_l1/emspectrum.html

Greco-Roman Times Patterns in the night sky Are the objects in the sky similar each night? What changes over time? Use Stellarium to look at the movement of stars, including the sun, the moon and the planets

Greco-Roman Times Myths and stories – Constellations – Movement of celestial objects The moon and stars consistently move in the same direction across the night sky (they rise and set) Planets sometimes reverse their direction, which is called retrograde motion The Greeks, Romans, and other cultures named the planets after gods, based on their characteristics. For example, in Roman mythology Mercury was a swift messenger; the planet that orbits the sun the fastest is named after him.

Greco-Roman Times The sun, the moon, and five planets--Mercury, Venus, Mars, Jupiter, and Saturn could be seen with the naked eye. These seven objects were used by many cultures to name the days of the week. English uses a blend of Roman and Germanic names: – Sunday: The sun's day. Sol was the Roman god of the sun. – Monday: The moon's day. Luna was the Roman goddess of the moon. – Tuesday: Tiu's day or Mars day. Tiu was the Germanic god of war. Mars was his Roman equivalent. – Wednesday: Woden's day or Mercury's day. Woden/Odin is sometimes described as the supreme Germanic god, but is also associated with the Roman god Mercury. – Thursday: Thor's day or Jove's Day. Thor was the Germanic god of thunder and lightning. Jupiter, or Jove, was the god of the heavens. – Friday: Freya's day or Venus' day. Freya is considered the Germanic equivalent of Venus, the Roman goddess of love and beauty. – Saturday: Saturn's day. Saturn was the Roman god of agriculture and of time. The Germanic tribes do not appear to have an equivalent.

Greco-Roman Times Aristotle’s Geocentric Model (or Earth-centered model) – 384BC – 322 BC – Dominated thinking for 2000 years – Earth at the centre of a giant sphere – Stars were attached to a fixed outer sphere – Sun, moon and known planets were attached to inner spheres

Greco-Roman Times Aristotle’s Geocentric Model – Was able to predict the movement celestial bodies that moved in the same direction around the Earth – Did not explain the fact that some planets were observed to sometimes reverse their direction

Greco-Roman Times Ptolemy’s geocentric model – Modified Aristotle’s model by giving planets another level of circular motion called “epicycles” – Successful in describing the sometimes retrograde (or backwards) movement of planets – Video Video

Greco-Roman Times – Journal Entry Oral story telling has long been a strong familial tradition. These stories are often passed down from generation to generation. You will write a descriptive journal entry in the voice of a Greek or Roman citizen who would have lived between 500BC to 200AD. Your purpose will be to recount a story of the night sky that would have been passed down by members of your family. You might choose to write the story of a constellation, the moon, the sun or a planet. You must make sure that your story is clearly influenced and shaped by the geocentric model of the universe and that it is written using descriptive language that “paints a picture” for the reader.