36 episodes

Part 10: Bodies throughout the solar system and their characteristics and properties.

These short videos were created in August 2007 by Dr. Christopher D. Impey, Professor of Astronomy at the University of Arizona, for his students. They cover a broad range of terms, concepts, and princples in astronomy and astrobiology. Dr. Impey is a University Distinguished Professor and Deputy Head of the Astonomy Department. All videos are intended solely for educational purposes and are licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. The full list of collections follows below:

01. Fundamentals of Science and Astronomy
02. Ancient Astronomy and Celestial Phenomena
03. Concepts and History of Astronomy and Physics
04. Chemistry and Physics
05. Quantum Theory and Radiation
06. Optics and Quantum Theory
07. Geology and Physics
08. Solar Neighborhood and Space Exploration
09. Outer Planets and Planetary Atmospheres
10. The Solar System
11. Interplanetary Bodies
12. Formation and Nature of Planetary Systems
13. Particle Physics and the Sun
14. Stars 1
15. Stars 2
16. Stars 3
17. Galactic Mass Distribtuion and Galaxy Structure
18. Galaxies
19. Galaxies 2
20. Galaxy Interaction and Motion
21. Deep Space and High-Energy Phenomena
22. The Big Bang, Inflation, and General Cosmology
23. The Big Bang, Inflation, and General Cosmology 2
24. Chemistry and Context for Life
25. Early Earth and Life Processes
26. Life on Earth
27. Life in the Universe
28. Interstellar Travel, SETI, and the Rarity of Life
29. Prospects of Nonhuman Intelligences

10. The Solar System University of Arizona

    • Science

Part 10: Bodies throughout the solar system and their characteristics and properties.

These short videos were created in August 2007 by Dr. Christopher D. Impey, Professor of Astronomy at the University of Arizona, for his students. They cover a broad range of terms, concepts, and princples in astronomy and astrobiology. Dr. Impey is a University Distinguished Professor and Deputy Head of the Astonomy Department. All videos are intended solely for educational purposes and are licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. The full list of collections follows below:

01. Fundamentals of Science and Astronomy
02. Ancient Astronomy and Celestial Phenomena
03. Concepts and History of Astronomy and Physics
04. Chemistry and Physics
05. Quantum Theory and Radiation
06. Optics and Quantum Theory
07. Geology and Physics
08. Solar Neighborhood and Space Exploration
09. Outer Planets and Planetary Atmospheres
10. The Solar System
11. Interplanetary Bodies
12. Formation and Nature of Planetary Systems
13. Particle Physics and the Sun
14. Stars 1
15. Stars 2
16. Stars 3
17. Galactic Mass Distribtuion and Galaxy Structure
18. Galaxies
19. Galaxies 2
20. Galaxy Interaction and Motion
21. Deep Space and High-Energy Phenomena
22. The Big Bang, Inflation, and General Cosmology
23. The Big Bang, Inflation, and General Cosmology 2
24. Chemistry and Context for Life
25. Early Earth and Life Processes
26. Life on Earth
27. Life in the Universe
28. Interstellar Travel, SETI, and the Rarity of Life
29. Prospects of Nonhuman Intelligences

    • video
    Origin of Rings

    Origin of Rings

    Transcript: Where did the rings of the giant planets come from? Interplanetary debris has rained down upon the giant planets and the moons of the giant planets since the formation of the solar system four and a half billion years ago. Some of the giant planets undoubtedly accreted a ring of debris material early in their history, yet more of the material must have come from impacts of interplanetary debris on the inner moons of the planets themselves. Some of these impacts sandblasted the moons, leading to small particles that get ejected from the moons and spread out into a ring, yet more material that forms rings must have come from the disruption of moons entirely by a shattering impact. Thus, its possible that many of the moon systems of the planets have lead directly to the ring systems and that those ring systems have not been the same over the history of the solar system.

    • 57 sec
    • video
    Structure of Saturn's Rings

    Structure of Saturn's Rings

    Transcript: The rings of Saturn are spectacular and highly complex. The Voyager space probes showed the existence of thousands of individual ringlets, with the widest gap being Cassini's division, which was discovered in the seventeenth century. The particle sizes within the rings range from golf ball size up to about the size of a house. Larger blocks of material are broken down by collisions. The material is mostly made of frozen ices rather than dark, rocky material, so the rings are relatively pale in color. The most spectacular thing about the rings is their aspect ratio. The rings are 270,000 kilometers from edge to edge but only 100 meters thick. They are millions of times thinner than they are wide. It's as if you had a pizza that was less than the thickness of a human hair.

    • 54 sec
    • video
    Resonance

    Resonance

    Transcript: Resonance is a phenomenon that’s common to all vibrations and waves. It’s a situation where a vibration, a wave, or an oscillation caused by one object induces a vibration, a wave, or an oscillation in another object. Obvious example of resonance is the fact that soldiers must break step when they walk across a bridge in case the pattern of their marching motion corresponds to a natural frequency of the bridge, in which case the marching adds energy to the bridge motion which amplifies it into a wave that could destroy the bridge. A better example is pushing a child on a swing. Assume you walk up to a swing where a child is swinging. If you then push the swing with random intervals you will on average loose energy from the swing and the swing will stop. If, however you wait until the swing is just moving forward or every second forward motion or every third or forth or fifth forward motion you will add energy to the swing. This is a resonance. At a fixed period interval, adding energy to the system will increase the original motion. You can see this also occurring with a bell or a tuning fork. If the bell is struck or the tuning fork is struck a similar bell or tuning fork some distance away will resonate.

    • 1 min
    • video
    Tidal Forces

    Tidal Forces

    Transcript: Gravity keeps planets in their orbit of the Sun and keeps moons in their orbit of the planets. There is a second type of force that is important, however, in the solar system, tidal force. A tidal force is caused by the difference between the gravity force on one side of an object and the other side. It's essentially a stretching force. The size of a tidal force depends on the ratio between the front to back distance, or diameter, of an object like a moon or a planet and its distance from the object causing the gravity. If you work this out for the Earth, Sun, and the Moon you find out that although the Sun’s gravity pull on the Earth is much larger than the Earth’s gravity pull, the tidal force of the Moon exceeds that of the Sun by a factor of two. Thus, tides are caused primarily by the Moon but with a secondary contribution from the Sun. This explains why tides on the Earth are larger at new and full moons when the Sun and the Moon and the Earth all line up.

    • 1 min
    • video
    Roche Limit

    Roche Limit

    Transcript: All ring systems in the solar system have outer edges that are somewhere between 1.8 and 2.5 times the planet radius from the center of the planet. What is particular about this ratio and how does it arise? The answer was derived in the mid-nineteenth century by the French mathematician Edward Roche. He calculated that the edge of planetary rings is defined by tidal forces. If we consider the gravity force between particles composing a planetary ring, the Roche limit, as it's called, is defined by the distance in which the tidal force caused by the planet on the particles equals the gravity force between them. Therefore beyond the Roche limit rings cannot exist because the tidal force is too large.

    • 53 sec
    • video
    Size of Moons

    Size of Moons

    Transcript: Is there something that sets the maximum size of the moon of a planet? The answer to this question complex, but one part of the answer is Roche's limit. The tidal force on a moon increases both with the size of the moon and it's proximity to the planet. Thus, a moon that is large and close to a planet will have a large tidal force, and at some point that tidal force will disrupt the solid material and break apart the moon leading perhaps to a ring system. Thus, moons that are too close and too large to their planets will be disrupted, destroyed, and eventually end up as ring systems. Thus, we should not be surprised that most moons are substantially smaller then their parent planets and relatively far away. Earth's moon in this regard is relatively large being only a quarter the size of the Earth and about one-eightieth of the mass. We should also remember that not all moons and rings are related in an evolutionary sense; some moons have been captured gravitationally from other parts of the solar system.

    • 1 min

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