Date: October 26, 2011
Title: Saturn’s Moon Phoebe
Podcaster: Thomas Hofstätter and Leon Dumbroski
Link: Hidden Space Project
Description: Observing the other solar system, the Saturn ring system surely is one of the most interesting places. The structure of the system, including the flat rings and the moons, opens a huge field of exploration for professional scientists as well as for amateurs. This podcast describes the possibly most interesting part of the whole system: Phoebe and its ring.
If you have any questions, comments or suggestions to the podcast, feel free to write me an email to hidden-space (at) gmx (dot) at or visit me at my website at www.hidden-space.at.tf!
Bio: Born in 1993 near Vienna, Austria, Europe. Upper High School with focus on Computer Science.Interested in extreme small and extreme big, devious and uninvestigated things. My main aim is to bring astronomy to public and to establish secular interest in astronomy, physics and mathematics. Host of :: The Hidden Space Project :: at http://hidden-space.at.tf.
Sponsor:This episode of “365 Days of Astronomy” has been sponsored by AARTScope.blogspot.com, helping create the sense of anticipation and discovery that keep us asking questions”
Transcript:
Hello and welcome to this episode of 365 Days of Astronomy. My name is Thomas Hofstätter and I am the host of :: The Hidden Space Project :: at www.hidden-space.at.tf.
[Leon:] And I’m Leon Dombroski from the State of Connecticut in the United States.
In this podcast, Leon and I are describing the Saturn System and the moon and ring Phoebe in special.
This podcast is dedecated to my friend Phoebe. Thanks for always making me think of the weirdest scientific things and all the best for your today’s birthday!
Have fun with the podcast!
[Leon:] Observing the other solar system, the Saturn ring system surely is one of the most interesting places. The structure of the system, including the flat rings and the moons, opens a huge field of exploration for professional scientists as well as for amateurs. Even for smaller telescopes, the ring system, some of the moons and perhaps the Cassini division are visible.
Of course, professional scientists have probes like the Cassini spacecraft on hand. But also the Hubble Space Telescope has made some quite important explorations at Saturn. Although the planet is known since ancient times, just in 2009, the Spitzer Space Telescope discovered another, much huger ring than all the previously known ones. The most stunning fact about this ring: It’s formed out of material of the moon Phoebe.
[Leon:] The ring spans about 300 times the diameter of Saturn and is 20 times thicker than the planet itself. But although it’s so huge, scientists haven’t detected it earlier because you wouldn’t even notice it if you were right in it due to the low number of particles in it. That makes it nearly impossible to view the ring using optical telescopes. Using the Spitzer Space Telescope as an infrared telescope, the ring becomes visible because of the relatively high temperature. The particles absorb energy of the sun and store it.
Phoebe is one of the farthest moons of Saturnian’s system and lies directly in the ring. Scientists think that the relatively small moon is the source of the ring. Shortly after its detection, the ring got the name “Phoebean Ring” named after the moon that has been detected in 1899 by W.H. Pickering, an American astronomer.
[Leon:] Voyager 2 accomplished the first flyby in 1981 at a distance of 2.2 million km. But the resolution was low and the data nearly worthless. But since this date, scientists know that Phoebe isn’t the outermost of the now known 62 moons of Saturn.
The Cassini spacecraft made the next flyby in 2004 at Phoebe’s best part of orbit. It sent back the best images available until now. Because Phoebe is rotating around its axis once every ten hours, Cassini was able to map nearly the whole surface in high resolution. Scientists now think that Phoebe once was a Kuiper Belt Object (KBO) that has been trapped by Saturn’s gravity and forced into an eccentric orbit with a tilt of 27°.
[Leon:] The moon has a diameter of about 220km and a temperature of 75Kelvin or -198Celsius. That’s 5° less than the temperature of the ring. Orbiting around Saturn in about 18 months at a quite high distance from Saturn of about 110 times the diameter of the planet, Phoebe is exposed to the high amounts of particles that fly around in the solar system. That causes it to have craters up to 80km of diameter. Same as the name of the moon, the IAU officially named 25 craters on the surface of Phoebe after characters in Greek mythology.
The material of Phoebe’s surface is quite dark in contrast to the inner moons of Saturn. When Micrometeorites collide with Phoebe, material is dashed out into space and caught by the gravitational force of Jupiter. Another way, material may end is by falling onto the surface of another moon orbiting Saturn.
[Leon:] At the time, two moons are known that might have material of Phoebe on their surface. The first is Iapetus that is known for the high contrast on its surface. The other is Hyperion, known for its quite dark surface. Both of them orbit at the edge or in the Phoebean Ring and hence can collect material of it.
That’s it for today. I hope, you enjoyed it. If you have any questions, comments or suggestions, write me an email to hidden-space (at) gmx (dot) at or visit me at my website at www.hidden-space.at.tf.
Thanks for listening and clear-skies!
[Leon:] Good bye for now!
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Links for further information:
- Spitzer Space Telescope article
- Spitzer Space Telescope release
- Description of Phoebe and missions to the moon
- Video Tour through Saturn’s system
End of podcast:
365 Days of Astronomy
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