Lesson plan
Classical planet
A classical planet is an astronomical object that is visible to the naked eye and moves across the sky and its backdrop of fixed stars (the common stars which seem still in contrast to the planets), appearing as wandering stars. Visible to humans on Earth there are seven classical planets (the seven luminaries). They are from brightest to dimmest: the Sun, the Moon, Venus, Jupiter, Mercury, Mars and Saturn. Greek astronomers such as Geminus and Ptolemy recorded these classical planets during classical antiquity, introducing the term planet, which means 'wanderer' in Greek ( and ), expressing the fact that these objects move across the celestial sphere relative to the fixed stars. Therefore, the Greeks were the first to document the astrological connections to the planets' visual detail. Through the use of telescopes other celestial objects like the classical planets were found, starting with the Galilean moons in 1610. Today the term planet is used considerably differently, with a planet being defined as a natural satellite directly orbiting the Sun (or other stars) and having cleared its own orbit. Therefore, only five of the seven classical planets remain recognized as planets, alongside Earth, Uranus, and Neptune.
Article summary
A classical planet is an astronomical object that is visible to the naked eye and moves across the sky and its backdrop of fixed stars (the common stars which seem still in contrast to the planets), appearing as wandering stars. Visible to humans on Earth there are seven classical planets (the seven luminaries). They are from brightest to dimmest: the Sun, the Moon, Venus, Jupiter, Mercury, Mars and Saturn. Greek astronomers such as Geminus and Ptolemy recorded these classical planets during classical antiquity, introducing the term planet, which means 'wanderer' in Greek ( and ), expressing the fact that these objects move across the celestial sphere relative to the fixed stars. Therefore, the Greeks were the first to document the astrological connections to the planets' visual detail. Through the use of telescopes other celestial objects like the classical planets were found, starting with the Galilean moons in 1610. Today the term planet is used considerably differently, with a planet being defined as a natural satellite directly orbiting the Sun (or other stars) and having cleared its own orbit. Therefore, only five of the seven classical planets remain recognized as planets, alongside Earth, Uranus, and Neptune.
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.