Amateurs Help Professionals Study the Giant Planets

Professional planetary scientists with the International Outer Planets Watch depend on amateur observations of the giant planets. Amateurs produce near-continuous coverage of the planets and spot asteroid and comet impacts on Jupiter. Without amateurs' observations, planetary scientists would have a much harder time exploring the outer planets.

Planetary scientists’ greatest advantage - spacecraft that study their subjects directly - is also planetary science’s greatest weakness. Planetary missions are so expensive and take so long to develop that years pass between visits. In between those visits, planetary scientists must rely on data from ground-based observatories and space telescopes. But competition for oberving time is fierce - these facilities are oversubscribed many times over - and astrophysics has the higher priority. Getting time at an observatory - and the grants to pay for it - only goes to the most important or most urgent planetary research projects.

Visits to Jupiter

  • 1973 - Pioneer 10 fly-by

  • 1974 - Pioneer 11 fly-by

  • 1979 - Voyager 1 and 2 fly-by

  • 1985 - Galileo arrives

  • 1992 - Ulysses fly-by #1

  • 2000 - Cassini fly-by

  • 2003 - Galileo ends

  • 2004 - Ulysses fly-by #2

  • 2007 - New Horizons fly-by

  • 2016 - Juno arrives

  • 2017 - Juno ends

  • 2030 - Juice arrives

  • 2033 - Juice ends

As scientists prepared in the 1980’s for Nasa’s Galileo mission to Jupiter, they realized they needed to work smarter. They created the International Jupiter Watch as a grass-roots effort to coordinate research into the giant planet. The IJW didn’t have any money to award or any authority over observatory allocation committees. But by letting scientists place their work in the larger context of global coordinated research the IJW strengthened scientists’ research proposals and made the proposals more competitive in the search for grants and observing time. The IJW’s approach worked so well that scientists expanded its focus to the rest of the outer Solar System, renaming the group the International Outer Planets Watch.

Cassini caught this picture of Jupiter and its moon Io during one of the handful of fly-bys of the giant planet.  (Source: Nasa/JPL/University of Arizona

Cassini caught this picture of Jupiter and its moon Io during one of the handful of fly-bys of the giant planet.  (Source: Nasa/JPL/University of Arizona

The IOPW’s scientists recognized from the beginning that amateurs could contribute to outer planet studies. Research that requires many observations over long periods of time don’t fit into the Big Science economics. Tracking changes in Jupiter’s atmosphere just isn’t important enough to justify setting aside several hours of observing time every night. Amateur astronomers, on the other hand, have all the time in the world to make whatever observations interest them. Factor in the sheer number of amateur astronomers around the world and you get near-continuous monitoring of Jupiter and the other outer planets.

Amateurs’ widespread presence combined with technological changes at the turn of the century to make amateurs an increasingly important part of the IOPW’s plans. In 1993 mateur astronomers David Levy and Caroline Shoemaker discovered a comet, Shoemaker-Levy 9, on a collision course for Jupiter. The entire world watched through the eyes of the Hubble Space Telescope as the comet broke up and smashed into the giant planet. The 2003 IOPW Steering Committee Meeting recognized the high quality of amateur work using CCD cameras. It launched the Planetary Virtual Observatory and Laboratory archive to collect these scientifically-useful amateur images of the outer planets.  The 2005 IOPW Steering Committee Meeting received presentations from amateur astronomers. By 2010 the IOPW developed software so amateurs could search for and report Jupiter impacts. The 2012 meeting of the IOPW’s Steering Committee declared:

The last [two years] have seen a large involvement of amateur astronomers in major discoveries related with Jupiter and Saturn. Those amateur achievements have attracted more amateurs to this field and has served to impulse a global improvement in observation quality. 

The dark spot at the top of the image is amateur astronomer Anthony Wesley's discovery of the 2009 Jupiter impact. (Source: Anthony Wesley)

The dark spot at the top of the image is amateur astronomer Anthony Wesley's discovery of the 2009 Jupiter impact. (Source: Anthony Wesley)

Image of 2009 Jupiter impact from the Hubble Space Telescope (Source:  NASA, ESA, H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team)

Image of 2009 Jupiter impact from the Hubble Space Telescope (Source:  NASA, ESA, H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team)

Australian amateur astronomer Anthony Wesley discovered a Jupiter impact in July 2009. His report sparked a mad dash among amateur and professional astronomers to observe the impact site before it faded from view. Amateur astronomers submitted images confirming the impact to the PVOL. Researchers at Nasa’s 3-meter Infrared Telescope Facility, who were already planning to observe Jupiter’s Great Red Spot, changed priorities to make their own observations of the impact. The Hubble Space Telescope was still being checked out after its recent upgrade by Nasa astronauts, but the Space Telescope Science Institute changed plans to make visible and ultraviolet observations. All of these observations produced dozens of scientific papers. Planetary scientist Agustín Sánchez-Lavega was the lead author of the most-cited paper, “The impact of a large object on Jupiter in July 2009”. (doi:10.1088/2041-8205/715/2/L155) Published in the peer-reviewed Astrophysical Journal Letters, you’ll see Anthony Wesley, computer programmer by profession and amateur astronomer by passion, listed as the second author.