Equatorial ridge on Iapetus

Equatorial ridge

Iapetus's equatorial ridge up close as imaged by Cassini
Feature type Mountains
Location Iapetus
Coordinates 0°N 0°W / 0°N -0°E / 0; -0Coordinates: 0°N 0°W / 0°N -0°E / 0; -0
Length 1,300 km
Peak 20 km
Discoverer Cassini

Saturn's moon Iapetus has a long, 20-kilometer-high ridge running along most of its equator. It was discovered by the Cassini probe in 2004. The ridge's origin is unknown. There are bright areas on the sides of the equatorial ridge near Iapetus's bright trailing hemisphere, which were already visible in Voyager images appearing like mountains and were nicknamed the "Voyager Mountains".[1]

Discovery

Iapetus's equatorial ridge was discovered when the Cassini spacecraft imaged Iapetus on 31 December 2004. Peaks in the ridge rise more than 20 km above the surrounding plains, making them some of the tallest mountains in the Solar System. The ridge forms a complex system including isolated peaks, segments of more than 200 km and sections with three near parallel ridges.[2]

Origins

Within the bright regions there is no ridge, but there are a series of isolated 10 km peaks along the equator.[3] The ridge system is heavily cratered, indicating that it is ancient. The prominent equatorial bulge gives Iapetus a walnut-like appearance.

It is not clear how the ridge formed. One difficulty is to explain why it follows the equator almost perfectly. There are at least four current hypotheses, but none of them explains why the ridge is confined to Cassini Regio.

References

  1. Iapetus' "Voyager Mountains"
  2. Porco, C. C.; E. Baker, J. Barbara, K. Beurle, A. Brahic, J. A. Burns, S. Charnoz, N. Cooper, D. D. Dawson, A. D. Del Genio, T. Denk, L. Dones, U. Dyudina, M. W. Evans, B. Giese, K. Grazier, P. Helfenstein, A. P. Ingersoll, R. A. Jacobson, T. V. Johnson, A. McEwen, C. D. Murray, G. Neukum, W. M. Owen, J. Perry, T. Roatsch, J. Spitale, S. Squyres, P. C. Thomas, M. Tiscareno, E. Turtle, A. R. Vasavada, J. Veverka, R. Wagner, R. West (2005-02-25). "Cassini imaging science: Initial results on Phoebe and Iapetus". Science. 307 (5713): 1237–1242. Bibcode:2005Sci...307.1237P. doi:10.1126/science.1107981. PMID 15731440. 2005Sci...307.1237P.
  3. "Cassini–Huygens: Multimedia-Images". Saturn.jpl.nasa.gov. Retrieved 2012-07-30.
  4. Kerr, Richard A. (2006-01-06). "How Saturn's Icy Moons Get a (Geologic) Life". Science. 311 (5757): 29. doi:10.1126/science.311.5757.29. PMID 16400121.
  5. Ip, W.-H (2006). "On a ring origin of the equatorial ridge of Iapetus". Geophysical Research Letters. 33: L16203. Bibcode:2006GeoRL..3316203I. doi:10.1029/2005GL025386.
  6. Czechowski, L.; J.Leliwa-Kopystynski (2012-09-25). "Isostasy on Iapetus: the myth of fossil bulge" (PDF). EPSC Abstracts. 7: 834.
  7. Czechowski, L.; J.Leliwa-Kopystynski (2013-09-25). "Remarks on the Iapetus' bulge and ridge" (PDF). Earth, Planets and Space. 65: 929–934. Bibcode:2013EP&S...65..929C. doi:10.5047/eps.2012.12.008.
This article is issued from Wikipedia - version of the 6/22/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.