|   | 
Credit & Copyright: G. Neukum   
(FU Berlin) et al., Mars Express,   
DLR,   
ESA;  
 Acknowledgement:  Peter Masek   
 
Explanation:
Why is Phobos so dark?    
  
Phobos, the largest and innermost of two  
Martian moons, is the darkest moon in the entire   
Solar System.    
  
Its unusual orbit and color indicate that it may be a captured   
asteroid composed of a mixture of ice and dark rock.    
  
The featured picture   
of Phobos near the limb of   
Mars   
was captured in 2010 by the robot spacecraft   
Mars Express currently orbiting Mars.    
  
Phobos is a heavily cratered and   
barren moon, with its   
largest crater located on the far side.    
  
From images like this,   
Phobos has been determined   
to be covered by perhaps a meter of   
loose dust.    
  
Phobos orbits   
so close to Mars that from some places it would appear to rise and   
set twice a day, but from other places   
it would not be visible at all.    
  
Phobos' orbit around Mars is   
continually decaying -- it will likely   
break up with pieces crashing to the Martian surface in about 50 million years.  
  
  
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NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: Phobos
Publications with words: Phobos
See also:
