The Reason We Have 7 Days in a Week

Neil deGrasse Tyson Explains...
11 Jul 202409:11

Summary

TLDRIn a lively discussion, the hosts explore the planets in our solar system, their historical significance, and their influence on the days of the week. They recount how ancient civilizations identified seven celestial bodies, leading to the naming of Sunday through Saturday after the Sun, Moon, and key planets like Mars and Venus. The conversation highlights the evolution of planetary classification, notably the exclusion of the Sun and Moon as planets, and the humorous inclusion of Uranus, once whimsically referred to as Planet George. This engaging dialogue combines astronomy, linguistics, and mythology, encouraging curiosity about the cosmos.

Takeaways

  • 🌍 The planets in order from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
  • 🕰️ Ancient cultures recognized seven celestial bodies as planets, including the Sun and the Moon.
  • 🔍 The term 'planet' comes from the Greek word 'planus,' meaning 'wanderer,' describing bodies that move against fixed stars.
  • 📅 Each day of the week is named after one of the seven ancient planets: Sunday (Sun), Monday (Moon), Tuesday (Mars), Wednesday (Mercury), Thursday (Jupiter), Friday (Venus), and Saturday (Saturn).
  • ⚔️ The name 'Tuesday' is linked to the Norse god Tiw, the god of war, corresponding to Mars.
  • 📬 'Wednesday' corresponds to Mercury, named after the messenger god known for speed.
  • ⚡ 'Thursday' is named after Thor, the Norse god associated with thunder, paralleling Jupiter in Roman mythology.
  • 💖 'Friday' is linked to Venus and the Norse goddess Frigg, embodying love and beauty.
  • 🔭 In the mid-1500s, Cernus proposed that the Sun and Moon should not be classified as planets, reducing the count to five.
  • 🌌 The discovery of Uranus was initially dubbed 'Planet George' after King George but didn't gain popularity.

Q & A

  • What are the planets in order from the Sun?

    -The planets in order from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

  • How did the ancient Greeks and Romans view planets?

    -Ancient Greeks and Romans viewed planets as celestial bodies that moved against the backdrop of fixed stars, leading to the term 'planets' meaning 'wanderers' in Greek.

  • How are the days of the week related to the planets?

    -Each day of the week is named after one of the seven ancient planets. For example, Sunday is named after the Sun, Monday after the Moon, Tuesday after Mars, and so on.

  • What is the significance of the number seven in relation to planets and the days of the week?

    -The number seven is significant because there were seven ancient planets recognized by the ancients, which corresponds to the seven days of the week.

  • What role does Norse mythology play in the naming of the days of the week?

    -Norse mythology influences the English names of the days of the week, such as Tuesday (Tiw's day, named after the Norse god of war) and Thursday (Thor's day, named after the god Thor).

  • What major change did Cernus introduce to the classification of planets?

    -Cernus proposed that the Sun and the Moon should not be classified as planets, which reduced the count of recognized planets from seven to five.

  • Which planet was humorously referred to as 'Planet George'?

    -The planet Uranus was humorously referred to as 'Planet George' after King George III, but this name was not widely accepted.

  • Why do the speakers mention the concept of 'fixed stars'?

    -The concept of 'fixed stars' refers to stars that appear to stay in place against the backdrop of moving celestial bodies, which were categorized as planets by the ancients.

  • How did the speakers view the naming of the planets and the days of the week?

    -The speakers expressed that the naming of the planets and days reflects a rich blend of cultural influences, mythology, and historical context, highlighting the romance of astronomy.

  • What is the overall theme of the conversation in the transcript?

    -The overall theme is an exploration of the historical relationship between planets, their names, and the days of the week, combining elements of science, mythology, and language.

Outlines

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Related Tags
PlanetsDays of WeekAstronomyCultural HistoryMythologyEducationalScienceEngaging DialoguePlanet NamesNorse Influence