Shoemaker-Levy 20th Anniversary

Impact of comet with Jupiter

Image of Jupiter taken by Peter McGregor 12 minutes after an impact.

20 years ago, comet Shoemaker-Levy 9 made headlines around the world when it crashed into Jupiter. The impacts produced the biggest planetary explosions scientists have ever seen.

Astronomers were able to calculate that Shoemaker-Levy 9 had passed so close to Jupiter two years before impact that the giant planet’s powerful gravity had pulled the comet apart into fragments.

Shoemaker-Levy 9 Fragments

Shoemaker-Levy fragments flying through space two months before impact. Fragment G caused the explosion shown in the image page top. Hubble Image from NASA.

Don’t make the mistake that the word ‘fragment’ here means these were tiny particles. Three of the fragments were 1 km or more across.

This was a science story so big that it made headlines all over the world. The single explosion shown page top released the same amount of energy as a simultaneous detonation of 400 million Hiroshima sized nuclear bombs.

Jupiter’s clouds were left with dark scars where the impacts took place, which lingered for weeks.

Jupiter following the impacts. The dark patches caused by the impacts are almost Earth sized.

Jupiter following the impacts. The dark patches caused by the impacts are as big as planet Earth.

You can read more about the impacts on our Gene Shoemaker page.

So, What’s Been Happening Since?

Just last year, the Herschel Space Observatory captured this image, showing water in Jupiter’s stratosphere.

Water in Jupiter's Stratosphere

Image by ESA/Herschel/T. Cavalié et al.; Jupiter image: NASA/ESA/Reta Beebe (New Mexico State University)

A minimum of 95 percent of this water actually came from Shoemaker-Levy 9 when it vaporized in Jupiter’s atmosphere. The highest water concentrations are in the cyan/white areas of the image. The highest concentrations are in Jupiter’s southern hemisphere, where the comet struck.

Clearly, after 20 years, Jupiter is still feeling the effects of the comet impact!

But Wait, There’s More (Impacts)

Most of the scientists who were involved in the Shoemaker-Levy 9 observations felt they were watching a once-in-a lifetime event. However…

In 2009, astronomy enthusiast Anthony Wesley was imaging Jupiter from his backyard in Murrumbateman, Australia. A dark patch caught his eye, a patch which reminded him of one of the biggest astronomy stories he’d known in his life.

It looked very much like the scars he had seen on Jupiter from Shoemaker-Levy 9’s impacts.

Anthony Wesley quickly let the world’s astronomy community know what he had seen.

Telescopes around the world turned to focus once again on Jupiter.

And, sure enough, there it was… a new impact scar.

jupiter impact scar 2009

Jupiter scar from impact in 2009. NASA image from the Hubble Wide Field Camera 3.

Experience with the Shoemaker-Levy 9 impacts allowed astronomers to estimate the object that hit Jupiter in 2009 was a few hundred meters across.

So what else does the 2009 impact tell us?

The 2009 collision means that:

Either impacts are much more frequent than astronomers thought. Most astronomers thought there wouldn’t be another major impact on Jupiter for hundreds of years…


We’ve been lucky to see such rare impact events twice within the space of 15 years.

I don’t know about you, but personally, I’m hoping it’s the latter of these two possibilities!


30 Brilliant Scientist Quotes

Fantastically quotable scientists on science:

Georg Christoph LichtenbergIt is strange that only extraordinary men make the discoveries, which later appear so easy and simple.

Georg C. Lichtenberg, 1742 to 1799
PhilolausActually, everything that can be known has a Number; for it is impossible to grasp anything with the mind or to recognize it without this.

Philolaus, c. 470 – c. 385 BC
Scientist and Philosopher
paul erdosGod created two acts of folly. First, He created the Universe in a Big Bang. Second, He was negligent enough to leave behind evidence for this act, in the form of microwave radiation.

Paul Erdős, 1913 to 1996
william ramsayProgress is made by trial and failure; the failures are generally a hundred times more numerous than the successes ; yet they are usually left unchronicled.

William Ramsay, 1852 to 1916
victor schefferAlthough Nature needs thousands or millions of years to create a new species, man needs only a few dozen years to destroy one.

Victor Scheffer, 1906 to 2011
Nicolaus CopernicusThere may be babblers, wholly ignorant of mathematics, who dare to condemn my hypothesis, upon the authority of some part of the Bible twisted to suit their purpose. I value them not, and scorn their unfounded judgment.

Nicolaus Copernicus, 1473 – 1543
Astronomer, Mathematician
ernest rutherfordIf your experiment needs statistics, you ought to have done a better experiment.

Ernest Rutherford, 1871 to 1937
aristotleBy ‘life,’ we mean a thing that can nourish itself and grow and decay.

Aristotle, 384 BC to 322 BC
Scientist, Philosopher
george waldA physicist is an atom’s way of knowing about atoms.

George Wald, 1906 to 1997
100-man-grayDid the genome of our cave-dwelling predecessors contain a set or sets of genes which enable modern man to compose music of infinite complexity and write novels with profound meaning? …It looks as though the early Homo was already provided with the intellectual potential which was in great excess of what was needed to cope with the environment of his time.”

Susumu Ohno, 1928 to 2000
max planckAn experiment is a question which science poses to Nature, and a measurement is the recording of Nature’s answer.

Max Planck, 1858 to 1947
Theoretical Physicist
justus von liebigA fact acquires its true and full value only through the idea which is developed from it.

Justus von Liebig, 1803 to 1873
john wheelerThere is no law except the law that there is no law.

John Archibald Wheeler, 1911 to 2008
Theoretical Physicist
thomas chrowder chamberlinFalsity in intellectual action is intellectual immorality.

Thomas Chrowder Chamberlin, 1843 to 1928
100-fred-hoyleOutstanding examples of genius – a Mozart, a Shakespeare, or a Carl Friedrich Gauss – are markers on the path along which our species appears destined to tread.

Fred Hoyle, 1915 to 2001
steven weinbergIt does not help that some politicians and journalists assume the public is interested only in those aspects of science that promise immediate practical applications to technology or medicine.

Steven Weinberg , 1933 to present
Theoretical Physicist
john haldaneScience is vastly more stimulating to the imagination than the classics.

J. B. S. Haldane, 1892 to 1964
carl saganValid criticism does you a favor.

Carl Sagan, 1934 to 1996
jw mellorTrial by combat of wits in disputations has no attraction for the seeker after truth; to him, the appeal to experiment is the last and only test of the merit of an opinion, conjecture, or hypotheses.

Joseph Mellor, 1869 to 1938
arthur eddingtonWhat is possible in the Cavendish Laboratory may not be too difficult in the sun.

Sir Arthur Eddington, 1882 to 1944
Astronomer, Physicist, Mathematician
marie curiePierre Curie voluntarily exposed his arm to the action of radium for several hours. This resulted in damage resembling a burn that developed progressively and required several months to heal. Henri Becquerel had by accident a similar burn as a result of carrying in his vest pocket a glass tube containing radium salt. He came to tell us of this evil effect of radium, exclaiming in a manner at once delighted and annoyed: “I love it, but I owe it a grudge.”

Marie Curie, 1867 to 1934
Chemist, Physicist
Subrahmanyan ChandrasekharThe black holes of nature are the most perfect macroscopic objects there are in the universe: the only elements in their construction are our concepts of space and time.

Subrahmanyan Chandrasekhar, 1910 to 1995
thomas thomsonChemistry, unlike other sciences, sprang originally from delusions and superstitions, and was at its commencement exactly on a par with magic and astrology.

Thomas Thomson, 1773 to 1852
robert kirshnerUnderstanding the history of matter and searching for its most interesting forms, such as galaxies, stars, planets and life, seems a suitable use for our intelligence.

Robert Kirshner, 1949 to present
stephen jay gouldWe are storytelling animals, and cannot bear to acknowledge the ordinariness of our daily lives.

Stephen Jay Gould, 1941 to 2002
thomas goldThings are as they are because they were as they were.

Thomas Gold, 1920 to present
arthur eddingtonI believe there are 15 747 724 136 275 002 577 605 653 961 181 555 468 044 717 914 527 116 709 366 231 425 076 185 631 031 296 protons in the universe and the same number of electrons.

Sir Arthur Eddington, 1882 to 1944
Astronomer, Physicist, Mathematician
william ramsayArchimedes’ finding that the crown was of gold was a discovery; but he invented the method of determining the density of solids. Indeed, discoverers must generally be inventors; though inventors are not necessarily discoverers.

William Ramsay, 1852 to 1916
George Johnstone StoneyA theory is a supposition which we hope to be true, a hypothesis is a supposition which we expect to be useful; fictions belong to the realm of art; if made to intrude elsewhere, they become either make-believes or mistakes.

George Johnstone Stoney, 1826 to 1911
manScience is the acceptance of what works and the rejection of what does not. That needs more courage than we might think.

Jacob Bronowski, 1908 to 1974
Mathematician, Biologist