Bright spots on Ceres
Several bright surface features (also known as faculae) were discovered on the dwarf planet Ceres by the Dawn spacecraft in 2015.
The brightest cluster of spots ("Spot 5") is located in an 80-kilometer (50 mi) crater called Occator.[1][2] The largest and brightest component of the cluster is in the center of the crater, with dimmer spots located towards this crater's eastern rim. Early in the orbital phase of the Dawn mission, the high albedo of these spots was speculated to be due to some kind of outgassing,[3] and subsequent closer images helped scientists determine that it is material with a high level of reflection, and suggested ice and salt as possibilities.[4] These bright features have an albedo of about 40%, four times brighter than the average of Ceres's surface.[5]
On 9 December 2015, scientists reported that the bright spots on Ceres may be related to a type of salt, particularly a form of brine containing hydrated magnesium sulfate (MgSO4·6H2O); the spots were also found to be associated with ammonia-rich clays.[6]
Arizona State University scientists have proposed that the bright spots are best explained as resulting from briny water erupted from Ceres' interior that subsequently sublimated, leaving behind only the salt deposits. [7]
Contents
Spot 5
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The brightest cluster of spots ("Spot 5") is located in an 80-kilometer (50 mi) crater called Occator,[1][2] which is located at 19.86° N latitude; 238.85 E longitude.[1][2]
Alan Duffy of Swinburne University suggested "a meteorite strike either shook covering material off the salty ice or heated it so that salty water rose to the surface as a geyser. The water escaped into space and now, only the salt remains."[8] A haze that fills around half of Occator crater and that does not extend over its rim[9] periodically appears around Spot 5, the best known bright spot, adding credence to the idea that some sort of outgassing or volcanism is occurring.[10][11]
Dawn's images led to widespread reports in the media about the bright spots, including in news sources,[12] astronomy magazines,[13] and science magazines.[14] An informal NASA poll during May offered the following ideas for the nature of the spots:[15] ice, volcanos, geysers, salt deposits, rock, or other.[16]
Asteroid specialist A. Rivkin noted, in an article by Sky & Telescope magazine, that at low angles a haze can be seen in but not outside of the crater, and speculated that this could be sublimated vapor from ice, possibly linked to the bright spots.[17]
Reflectivity studies from September 2015 suggest that the spots are probably salts rather than ice, implying that Ceres's interior is somehow delivering fresh salt to the surface.[18]
from 4,400 km (2,700 mi)
from 4,400 km (2,700 mi)
Spot 1
Planned observations
Dawn's closest orbit around Ceres is at a distance of 375 km (233 mi), started in early December 2015. This low-altitude mapping orbit (LAMO) is designed to acquire data for at least three months with Dawn's gamma-ray and neutron detector (GRaND) for gravity investigation and to determine the chemical composition on and near the surface.[19][4]
Gallery
(12 February 2015)
(6 June 2015)
(4 May 2015)
| Ceres – dwarf planet |
|---|
"Spot 1" (top row) (cooler than surroundings); "Spot 5" (bottom) (similar in temperature to surroundings) (April 2015). |
See also
- Ahuna Mons, the tallest mountain on Ceres
- Sublimation
References
- ↑ 1.0 1.1 1.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ LPSC 2015: First results from Dawn at Ceres: provisional place names and possible plumes
- ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ https://asunow.asu.edu/20151215-deep-freeze-puts-squeeze-dwarf-planet-ceres
- ↑ A. Duffy – Cosmos – What on Ceres are those bright spots?
- ↑ Chris Russel at [1]
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Dawn at Ceres: A haze in Occator crater? Posted by Andrew Rivkin
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Sky and Telescope magazine - Dawn Sees Ceres Bright Spots and More By Emily Poore July 30, 2015
- ↑ Ceres' Mysterious Bright Spots Aren't Made of Ice After All. Gizmodo, 1 October 2015
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
External links
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Wikimedia Commons has media related to Ceres (dwarf planet). |
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Wikimedia Commons has media related to Ceres bright spots (dwarf planet). |
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