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Episode 4:

with guest Dr. Heidi B. Hammel from the Space Science Institute

Heidi Hammel

On July 19, 2009, Australian amateur astronomer Anthony Wesley spotted a dark-colored scar high in the clouds over Jupiter's southern polar region. It looked like the scars left behind by Comet Shoemaker-Levy 9 when its shattered fragments crashed into Jupiter in the summer of 1994. Dr. Heidi B. Hammel is one of the astronomers who have studied the aftermath of this latest collision to learn about how Jupiter's atmosphere responds to such collisions. In this episode, Dr. Hammel discusses what her team learned from their observations of the collision site using Hubble, Gemini, and Keck cameras.

Listen (mp3, 6 MB)

Download Transcript (pdf)

Further Activities & Resources 


Produced by the Astronomical Society of the Pacific

Written and narrated by Carolyn Collins Petersen

Original music by Geodesium

Soundtrack production by Loch Ness Productions

Web page materials by Andrew Fraknoi

Special thanks to Dr. Heidi B. Hammel.

To learn more about Dr. Hammel and her work, visit her web pages:
Space Science Institute
I was wondering...

Exploring Jupiter and Impacts Further:
A Collection of Resources to Get Behind the Headlines

Andrew Fraknoi (Foothill College & ASP)
October 2009

Here are some materials for informal science educators (and their audiences) to delve more deeply into the topics discussed in this month's "Astronomy Behind the Headlines" podcast.


A1. Books and Articles

A2. Jupiter Observing Guides

A3. Jupiter Web Sites


B1. Information on Shoemaker-Levy 9

B2. Information on the Recent Jupiter Impact


C1. Background Information

C2. Impact Web Sites



Cassini global view of Jupiter

Jupiter is the largest of the giant planets in our solar system -- worlds which are made mostly of gas and liquid. Its great mass allows it to attract more cosmic debris than a smaller world would and it is thus more likely to experience impacts with comets and asteroids.

A1. Books and Articles

Aguirre, Edwin "Hubble Zooms in on Jupiter's New Red Spot" in Sky & Telescope, Aug. 2006, p. 26. On changes in the cloud patterns in the atmosphere.

Beatty, J. "Into the Giant" in Sky & Telescope, Apr. 1996, p. 20. On the work of the Galileo probe.

Beebe, R. Jupiter: The Giant Planet. 1994, Smithsonian Institution Press. Clear, non-technical summary.

Beebe, R. "Queen of the Giant Storms" in Sky & Telescope, Oct. 1990, p. 359. Excellent review of the Red Spot.

Hanlon, Michael The Worlds of Galileo: The Inside Story of NASA's Mission to Jupiter. 2001, St. Martin's Press. The story of the Galileo mission told by a journalist.

Harland, David Jupiter Odyssey: The Story of NASA's Galileo Mission. 2000, Springer. Detailed look at the spacecraft and what it found in the Jupiter system.

Johnson, T. "The Galileo Mission to Jupiter and Its Moons" in Scientific American, Feb. 2000, p. 40. Results about Jupiter, Io, Ganymede, and Callisto.

Stern, A. "Jupiter Up Close and Personal" in Astronomy, Aug. 2007, p. 28. A summary of observations from the New Horizons spacecraft flyby. (See also the Apr. 2007 issue, p. 32.)

A2. Jupiter Observing Guides

Bakich, M. "Planetary Observing: All Hail the King" in Astronomy, June 2006, p. 78. Good instructions and diagrams about observing Jupiter for amateurs.

McAnally, John Jupiter and How to Observe It. 2008, Springer. A book for amateur astronomers on how to make and report observations of the giant planet.

McRobert, A. "Dynamic Jupiter: An Observing Guide" in Sky & Telescope, May 2005, p. 67. A guide for serious amateur astronomers.

A3. Jupiter Web Sites

NASA Solar System Exploration Jupiter page:

Bill Arnett's Nine Planets Jupiter page:

National Space Sciences Data Center Jupiter page:

Galileo Mission to Jupiter:
(Galileo orbited Jupiter for almost 8 years, ending in 2003, and gave us a huge amount of information about the planet and its intriguing moons.)

Jupiter Events Site (how to find the planet or its red spot, and more):


Pieces of comet approaching Jupiter
Montage of the Pieces of Comet Shoemaker-Levy 9 approaching Jupiter (Hubble Space Telescope)

In summer 1994, Comet Shoemaker-Levy 9, which had earlier been broken into pieces by an encounter with Jupiter, returned to the vicinity giant planet and the 20+ fragments hit Jupiter sequentially. Although all the pieces hit on the back side (as seen from Earth), the fast rotation of Jupiter soon brought the impact clouds into our view and as many telescopes as possible turned in their direction. When the July 2009 impact struck Jupiter, it reminded astronomers of this much better observed event in 1994.

B1. Information on Shoemaker-Levy 9

Levy, David Impact Jupiter: The Crash Of Comet Shoemaker-Levy 9. 2003, Basic Books. A nice summary by the amateur astronomer who helped discover the comet.

Beatty, J. & Goldman, S. "The Great Crash of 1994: A First Report" in Sky & Telescope, Oct. 1994, p. 18.

Burnham, R. "Jupiter's Smash Hit" in Astronomy, Nov. 1994, p. 34.

Eicher, D. "Death of a Comet" in Astronomy, Oct. 1994, p. 40.

O'Meara, S. "The Great Dark Spots of Jupiter" in Sky & Telescope, Nov. 1994, p. 30.

Weissman, P. "Making Sense of Shoemaker-Levy 9" in Astronomy, May 1995, p. 48. Superb summary of what we learned and what we still don't know.

Web Sites

Dan Bruton's Frequently Asked Questions about the Impact:

Jeff Foust's Web Site with Information & Images:

Jet Propulsion Lab List of Sites and Images:

B2. Information on the Recent Jupiter Impact

Jupiter with impact feature
July 2009 impact feature on Jupiter; the dark smudge at lower right (Hubble Space Telescope)

Beatty, J. "Jupiter Takes a Hits" in Sky & Telescope, Nov. 2009, p. 34.

Hubble News Release (with image):

University of California, Berkeley News Release:

Website by Anthony Wesley, the Australian amateur astronomer who discovered the impact:


While astronomers had been warning the world's leaders about the dangers of asteroid and comet impacts for a number of years (and had begun searches for dangerous objects), it took the 1994 Shoemaker-Levy 9 impact with Jupiter, which got enormous media coverage, to wake the world at large to the threat. Since then, NASA funding and Congressional interest have led to far better organized searches, planning by the military, and practical proposals for dealing with a chunk of cosmic material that turns out to be aimed for our planet in the future.

C1. Background Information

Artist impression of impact on Earth
Artist Don Davis paints a large impact on Earth

Becker, L. "Repeated Blows" in Scientific American, Mar. 2002, p. 76. Controversy about whether there have been several extinction impacts in Earth's history.

Chyba, C. "Death from the Sky: Tunguska" in Astronomy, Dec. 1993, p. 38. Excellent review article about the 1908 impact in Siberia.

Cooke, B. "Fatal Attraction" in Astronomy, May 2006, p. 46. On the asteroid Apophis and its future close approaches to Earth.

Davis, J. "185 Million Years Before the Dinosaurs' Demise, Did an Asteroid Nearly End Life on Earth?" in Astronomy, Apr. 2008, p. 34. On a mass extinction of life on Earth 250 million years ago and whether an impact may have caused it.

Durda, D. "The Most Dangerous Asteroid Ever Found" in Sky & Telescope, Nov. 2006, p. 28. On Apophis and its close approaches to the Earth and on the gravity tractor scheme for deflecting dangerous asteroids.

Gallant, R. "Journey to Tunguska" in Sky & Telescope, Jne 1994, p. 38. Traveling to the 1908 impact site and new ideas about the Siberian impact.

Gasperini, L., et al. "The Tunguska Mystery" in Scientific American, June 2008, p. 80. A more detailed exploration of the site of the 1908 impact over Siberia.

Kring, D. "Blast from the Past" in Astronomy, Aug. 2006, p. 46. Fine review of the impact that made Arizona's large Meteor (Barringer) Crater.

Kring, D. & Durda, D. "The Day the World Burned" in Scientific American, Dec. 2003, p. 98. On what happened to the environment and life on Earth after the Chicxulub impact 65 million years ago.

Morrison, D. "Target Earth" in Astronomy, Oct. 1995, p. 34. Excellent overview article.

Reynolds, M. "Earth Under Fire" in Astronomy, Aug. 2006, p. 40. Impact craters on Earth and what they tell us about impacts on the planets.

Schweickart, R., et al. "The Asteroid Tugboat" in Scientific American, Nov. 2003, p. 54. A proposal to use gentle tugging to prevent an asteroid from hitting the Earth if we have lots of notice.

C2. Impact Web Sites

NASA's Asteroid and Comet Impact Hazards Site (kept by David Morrison):

Jet Propulsion Lab's Near Earth Objects Site:

B612 Foundation (set up by two astronauts to encourage technology to help us deflect any asteroids aimed at Earth):

Lunar and Planetary Institute: Introduction to Terrestrial Impact Craters (with images):


Impact Cratering (Using marbles and sand to demonstrate how craters are made; by Ronald Greeley):

Impact Craters (from the Hawaii Space Grant Consortium):

Exploring Meteorite Mysteries (series of activities from NASA that includes several relevant to this topic):

Solar System Collisions Simulator (not really an activity, just a computer-based calculator, but fun -- you get to select what kind of objects you want to hit each planet and then the computer shows you the result):