Long thought to be the 9th planet, then reclassified in 2006 as a dwarf planet, Pluto is now also honored as the first plutoid. It has an atmosphere and four known moons: Charon, Nix, Hydra, and P4. Since it passed perihelion in 1989, it has been receding from the sun and it was interesting that the atmosphere was still warming when we started observing it in 2002. We are now participating in monitoring the atmosphere’s temperature and density, with a view toward understanding conditions there when NASA’s New Horizons spacecraft arrives there in 2015.

Refereed Papers

• The recent expansion of Pluto’s atmosphere (Elliot et al., Nature 424, 165-168, 10 July 2003)
• The Structure of Pluto’s Atmosphere from the 2002 August 21 Stellar Occultation (Pasachoff et al., Astronomical Journal 129, 1718-1723, March 2005)
• Changes in Pluto’s Atmosphere: 1988-2006 (Elliot et al., Astronomical Journal 134, 1-13, July 2007)
• Waves in Pluto’s Upper Atmosphere (Person et al., Astronomical Journal 136, 1510-1518, October 2008)

Abstracts

• Changes in Pluto’s Atmosphere Revealed by the P126A Occultation (Buie et al., B.A.A.S. 34, No. 3, 877, 9 October 2002)
• Pluto Occultation of P131.1 in 2002 August: Overview of Observations and Infrared Results (Elliot et al., B.A.A.S. 34, No. 4, 1211, 7 January 2003)
• High-Time-Resolution White-Light Observations of Pluto’s Occultation of P131.1 in 2002 August (Pasachoff et al., B.A.A.S. 34, No. 4, 1211, 7 January 2003)
• Examination of Pluto’s Figure with the P131.1 Stellar Occultation (Person et al., B.A.A.S. 34, No. 4, 1211-12, 7 January 2003)
• Pluto’s Atmospheric Figure from the P131.1 Stellar Occultation (Person et al., B.A.A.S. 35, No. 4, 957, September 2003)
• Fascinating Pluto (Pasachoff et al., Physics Today Vol. 57, Issue 9, pp. 18, September 2004)
• A Search for Rings, Moons, or Debris in the Pluto System during the 2006 July 12 Occultation (Pasachoff et al., B.A.A.S. 38, No. 3, 523, September 2006)
• Pluto’s atmospheric structure: results from the 2006 June 12 stellar occultation (Gulbis et al., B.A.A.S. 38, No. 3, 541, September 2006)
• The Size of Pluto’s Atmosphere As Revealed by the 2006 June 12 Occultation (Elliot et al., B.A.A.S. 38, No. 3, 541, September 2006)
• Stellar Occultation by Pluto of P445.3 (2UCAC 25823784) on 2007 March 18 (UT) (Person et al., IAU Circular 8825 as “(31340) Pluto”)
• Observational Results from the 2007 March 18 Pluto Stellar Occultation (Pasachoff et al., B.A.A.S. 39, No. 3, 541, October 2007)
• High Altitude Structure in Pluto’s Atmosphere from the 2007 March 18 Stellar Occultation (Person et al., B.A.A.S. 39, No. 3, 519, October 2007)
• Probing small bodies in the outer solar system with stellar occultations (Person et al., European Planetary Science Conference 2008, Münster)
• Pluto Stellar Occultation on 2008 Aug 25 (Buie et al., B.A.A.S. 41, No. 1, 562-563, January 2009)
• The 3/4 July 2010 Pluto Stellar-Occultation Observations (Pasachoff et al., 2010)
• Pluto’s Atmosphere from the July 2010 Stellar Occultation (Person et al., 2010)
• Stellar-Occultation Web Pages for Education and Planning (Pasachoff et al., 2010)

Miscellaneous Information

• 1988 Pluto Occultation Lightcurve PowerPoint
• August 2002 Pluto Occultation PowerPoint
• 2002 Pluto Occultation Press Release
• June 2006 Pluto Occultation PowerPoint
• March 2007 Pluto Occultation PowerPoint
• June 2008 Pluto Occultation Path PowerPoint
• August 2008 Pluto Occultation PowerPoint
• July 2010 Pluto Occultation PowerPoint
• July 2010 Pluto Occultation Path
• July 2010 Pluto Occultation Prediction by MIT Group
• May 22, 2011 Pluto Occultation Prediction by MIT Group
• June 23, 2011 Pluto Occultation Prediction by MIT Group
• June 27, 2011 Pluto Occultation Prediction by MIT Group
• July 20, 2011 NASA’s Hubble Discovers Another Moon Around Pluto
• New Horizons mission, NASA link
• New Horizons mission, JHU/APL link
• Wikipedia, “Pluto”
• Gallery of Images