Old Cat.

An A/CC Special Topic:

Pluto & Charon

Updated: 26 July 2003
[ back to A/CC News | back to A/CC Topics | New Horizons mission ]

More Pluto moons?

The New Horizons mission put out a 24 Feb. 2003 news release announcing an observation campaign to look for more satellites of Pluto.

Pluto impact?

Sky & Telescope in an 8 Jan. 2003 article, "Did Pluto Take a Punch?cookies required," reports that David Tholen and Marc Buie think they have detected in the eccentricity of Charon's orbit evidence of a Pluto impact or close encounter.

July & August 2002 stellar occultations

Early conclusions were mixed about what astronomers observed from 19-20 July and 21-22 August 2002 stellar occultations by Pluto and its companion Charon, but a number of Web sites posted information and images. It all began at MIT with Steve W. McDonald and James L. Elliot's occultation predictions, the first such opportunities since the first such observations were made in 1985 and 1988.

    2003 news
    • The journal Nature has three articles about Pluto's atmosphere in its July 10th issue, available for purchase. Related to this is an Observatory of Paris news release, "Drastic expansion of Pluto's atmosphere as revealed by stellar occultations." AFP (on SpaceDaily) and Reuters put out wire stories July 8th, had a July 9th report, "Puzzling Seasons and Signs of Wind Found on Pluto," and the Baltimore Sun had an article July 10th.
    2002 news sources
    • Lowell Observatory and the 20 July occultation:
      • Lowell Observatory 15 August news release
      • Lowell astronomer Marc Buie's trip diary about traveling to a remote spot in Chile with Oscar Saa of the Cerro Tololo Inter-American Observatory using a 14" portable telescope (finder chart)
      • News coverage included 16 Aug. and CNN 19 Aug. (headlined, "Pluto may be undergoing global warming"), and 20 Aug. 2002
    • European Southern Observatory (ESO):
      An ESO 28 August news release about its 8.2m VLT at Paranal capturing a near-miss of the 20 July event, and how these observations, of far higher resolution and corrected for atmospheric blurring, will be important in calibrating the results obtained with smaller portable telescopes that did observe the occultation. Included in the news release is a standalone explanation about using stellar occultations to study Pluto's atmosphere.
    • Massachusetts Institute of Technology (MIT):
      A 9 Oct. 2002 MIT news release, "Pluto is undergoing global warming, researchers find," reported that:
      Edward Dunham [of Lowell Observatory] is leading a team that is building HIPO, a SOFIA instrument designed specifically to observe occultations. [It] will provide very high-quality data on a much more frequent basis than is possible using ground-based telescopes alone. 
      Note: SOFIA is the 747-based infrared telescope slated to fly in 2003 and to begin regular operation in Fall 2004. It replaces the now mothballed Kuiper Airborne Observatory, which was also based at NASA/Ames, and was used to observe the 1988 Pluto stellar occultation. Visit to learn more.
    • Paris Observatory:
      Bruno Sicardy's report on both events (also preparations & goals), including some info about Francois Colas and his team with a 12" portable telescope that obtained 20 July observations.
    • Williams College:
      Williams has a page about observation of the 22 August occultation with the UHawaii 2.2m telescope. See also an earlier news release.
    • Mark Kidger occultation info
    2002 news coverage Next?
    • Sky & Telescope reportedcookies required there might be a 7 Nov. 2002 occultation event (not subsequently reported), and Bruno Sicardy says "the next favourable event will take place on May 22, 2005," visible from somewhere in the southern Pacific.
    • Doug Mink's Occultations by Pluto and Charon: 1993-2010

    1994 Hubble Space Telescope observations
    1988 stellar occultation
    Some references have the date wrong for the 1988 occultation. It was 9 June, not July.
    1978 Charon discovery & 1985 confirmation
    Charon was discovered on 22 June 1978 by James W. Christy at the U.S. Navy Observatory (USNO) in Washington, D.C. while measuring plates from the 1.55m USNO Flagstaff Station telescope. It had the temporary designation 1978 P 1.
    1949-1982 Pluto news
    1930 Pluto discovery & confirmation
    Pluto was discovered at Lowell Observatory near Flagstaff, Arizona on 18 Feb. 1930 by Clyde Tombaugh, and was announced in IAUC 255 of March 14th.

    More info about Pluto & Charon Pluto's future
    • posted an article 20 May 2003, "Hot Deal! Pluto, the Last Oasis for Life" (in a billion years, or so, as the Sun expands).
    Scientific references
    • Mapping Pluto using transits by Charon, 22 Jan. 2001 SwRI news item & preprint link, based on four observations made at McDonald Observatory in May 1987, April/June 1988 & April 1989
    • Pluto/Charon formation theory, 6 Oct. 1999 SwRI news release
    • The 895Kb PDF, "State of Knowledge of the Pluto-Charon System" (June 1999), from NASA/Langley's old Outer Planets Program Library Page, among other topics, delves into the apparent atmospheric thermal discontinuity found in the 1988 observations, one of the focal points of the new observations and analysis.
    • Distant EKOs Pluto bibliography (June 1999)
    Pluto — planet or minor object?

    [ page top | back to A/CC News | back to A/CC Topics | New Horizons mission ]
    Publisher information, privacy statement, and disclaimer.
    The contents and presentation of this page are © Copyright 2002-03 Columbine, Inc. - All Rights Reserved
    Please report broken links or other problems with this page to <>.
    Any mentioned trademarks are the property of their respective owners.
    Do NOT copy or mirror this page, but please do link to it.
    Individuals may make "snapshot" copies for their own private non-commerical use.