Lectures Watched
Since January 1, 2014
1500+ courses starting
in May 2017
Peruse my collection of 264
influential people of the past.
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My Notes on Massive Open Online Course:
Moons of Our Solar System
There are lots of moons in our Solar System. The Earth is the only planet with just a single moon. Some moons are bigger than ours; many are much smaller. There are even tiny moons orbiting some of the asteroids. Some have ongoing volcanic eruptions; others are dead, heavily cratered lumps. One has rivers and lakes of liquid methane. Our own Moon has resources that could help open the Solar System for future exploration. A small handful of moons have conditions below their surfaces where primitive life might exist.
Notes on 3 Lectures I Watched in This Course:
What is a Moon?
The Icy Moons
Naming Moons
2 People I Have Learned About in this Course:
Christiaan Huygens (1629-1695)
Leading Dutch mathematician and scientist of his time whose work included early telescopic studies of the rings of Saturn and the discovery of its moon Titan, and the invention of the pendulum clock
  • mathematical tutor Jan Jansz de Jonge Stampioen set the 15-year-old a demanding reading list on contemporary science
  • studied law and mathematics at the University of Leiden from 1645 to 1647
  • generally wrote in French or Latin
  • in 1655, Huygens proposed that Saturn was surrounded by a solid ring, "a thin, flat ring, nowhere touching, and inclined to the ecliptic"
  • in the same year, he observed and sketched the Orion Nebul, his drawing, the first such known of the Orion nebula
  • 1659, Huygens was the first to observe a surface feature on another planet, Syrtis Major, a volcanic plain on Mars
  • shortly before his death in 1695, Huygens completed Cosmotheoros, published posthumously in 1698, in which he speculated on the existence of extraterrestrial life on other planets which he imagined was similar to that on Earth
  • he argued that extraterrestrial life is neither confirmed nor denied by the Bible, and questioned why God would create the other planets if they were not to serve a greater purpose than that of being admired from Earth
  • Huygens postulated that the great distance between the planets signified that God had not intended for beings on one to know about the beings on the others, and had not foreseen how much humans would advance in scientific knowledge
Simon Marius (1573-1625)
German astronomer who claimed to have discovered four major moons of Jupiter some days before Galileo Galilei
  • Galileo accused Marius of plagiarism
  • a jury in The Netherlands in 2003 examined the evidence extensively and ruled in favor of Marius
  • while Galileo named the moons Jupiter I, Jupiter II, Jupiter III, and Jupiter IV, Marius named them after the lovers of Zeus, i.e. Io, Europa, Ganymede, and Callisto
  • drew conclusions about the structure of the universe from his observations of the Jovian moons and the
  • concluded from his observations of the Jovian moons that they must orbit Jupiter while Jupiter orbits the Sun
  • Marius concluded that the geocentric Tychonic system, in which the planets circle the Sun while the Sun circles the Earth, must be the correct world system, or model of the universe
  • spent most of his life in the city of Ansbach