Spitzer Space Telescope - General Observer Proposal #3180


Changing Seasons on Pluto:  A Stellar Occultation Opportunity

Principal Investigator: Amanda Bosh
           Institution: Boston University

Science Category: planets 
 Observing Modes: IracMap 
  Hours Approved: 0.7 

Abstract:
In 1989 Pluto passed perihelion and began its long swing further away
from the sun.  The decrease in solar insolation has led to predictions
of total atmospheric collapse.  However, a recent occultation
observation has revealed the opposite.  Continued occultation
observations are crucial in this period of transition, to determine
the behavior of Pluto's atmosphere as the system recedes from the sun.
Due to the small angular size of the planet, occultation events are
rare.  Fortuitously, an occultation by Pluto of a bright star, visible
from the Spitzer Space Telescope, is expected to occur in 2005.  This
event will provide atmospheric temperature and structure data, with a
signal-to-noise ratio per scale height of 1350, the highest yet
achieved.