Comet Shoemaker-Levy 9
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What is Comet Shoemaker-Levy 9?
Comet Shoemaker-Levy 9 was a comet whose disrupted nucleus crashed into Jupiter between July 16–22, 1994. It was the first collision between two solar system bodies ever predicted and observed. Astronomers Eugene and Carolyn Shoemaker and David Levy discovered it on March 25, 1993, in photographs taken at Palomar Observatory.
The comet's nucleus had broken into at least a dozen fragments. Analysis of the fragments' orbit revealed that the original comet had been captured into orbit around Jupiter around 1929. On July 8, 1992, tidal forces from Jupiter's gravity broke the original nucleus into 21 pieces, which then smashed into Jupiter’s atmosphere at 221,000 km (137,300 miles) per hour beginning on July 16, 1994. The impacts created fireballs that deposited dark clouds of ejecta on top of Jupiter's clouds.
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How was Comet Shoemaker-Levy 9 discovered?
On March 25, 1993, Comet Shoemaker-Levy 9 was discovered close to Jupiter by astronomers Eugene and Carolyn Shoemaker and David Levy. They identified it in photographs taken at the Palomar Observatory in California using an 18-inch (46-cm) Schmidt telescope.
The comet's appearance was highly unusual, featuring at least a dozen active cometary nuclei that lined up, looking like glowing pearls on a string. Further analysis revealed a total of 21 fragments, which led to the understanding that the original comet had been captured into orbit around Jupiter around 1929. In July 1992, it passed very closely to Jupiter, within 22,100 km above the planet's cloud tops, where tidal forces broke the nucleus into multiple pieces.
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What made Comet Shoemaker-Levy 9 different from other comets?
Comet Shoemaker-Levy 9 was unique because its disrupted nucleus crashed into Jupiter between July 16 and 22, 1994. This event marked the first observed collision between two solar system bodies that had been predicted in advance. The comet's unusual appearance, with at least a dozen active cometary nuclei aligned like "glowing pearls on a string," set it apart. Eugene and Carolyn Shoemaker and David Levy discovered it in March 1993, positioned close to Jupiter.
Tidal forces from Jupiter's gravity broke the original nucleus into 21 fragments, which then impacted Jupiter's atmosphere at 221,000 km per hour. The impacts created fireballs and deposited dark clouds of ejecta on Jupiter's clouds, which remained visible for weeks.
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Why did Comet Shoemaker-Levy 9 break into pieces?
Comet Shoemaker-Levy 9 broke into multiple fragments due to Jupiter's tidal forces. In July 1992, the comet passed within 22,100 km above Jupiter's cloud tops, well within the Roche limit. At such close range, the immense gravity of the planet overcame the comet's own gravity, resulting in the breakup of its nucleus, which was estimated to be 1.6 km in diameter, into 21 fragments. These fragments then collided with Jupiter in July 1994.
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What happened when the pieces of Comet Shoemaker-Levy 9 collided with Jupiter?
Comet Shoemaker-Levy 9 broke apart into 21 fragments due to Jupiter's gravity in 1992 and collided with the planet's atmosphere in July 1994 at 221,000 km per hour. The Galileo spacecraft, en route to Jupiter, directly observed the impacts, while telescopes on Earth also monitored the event. Each fragment created a super-hot gas bubble or "fireball" upon impact, leaving dark clouds of ejecta and fine cometary dust on Jupiter's clouds. The largest fragment, G, released energy equivalent to 48 billion tons of TNT, creating a black cloud larger than Earth. Spectroscopic studies revealed that the impacts had produced or delivered many chemicals such as water, hydrogen cyanide, and carbon monoxide.
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How did the collision of Comet Shoemaker-Levy 9 with Jupiter help scientists learn more about planets and comets?
The collision of Comet Shoemaker-Levy 9 with Jupiter in July 1994 was the first observed collision between two solar system bodies.
The impact helped scientists learn more about the composition of Jupiter's atmosphere. Spectroscopic studies revealed that the impacts had produced or delivered chemicals such as water, hydrogen cyanide, and carbon monoxide, substances that exist on Jupiter but in much smaller concentrations.
The event also stimulated detailed studies of the effects that cometary impacts would have on Earth.
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Comet Shoemaker-Levy 9, comet whose disrupted nucleus crashed into Jupiter over the period of July 16–22, 1994. The cataclysmic event, the first collision between two solar system bodies ever predicted and observed, was monitored from Earth-based telescopes worldwide, the Hubble Space Telescope and other Earth-orbiting instruments, and the Galileo spacecraft, which was en route to Jupiter.
On March 25, 1993, a previously unknown comet positioned close to Jupiter was discovered by Eugene and Carolyn Shoemaker and David Levy in photographs taken by using the 18-inch (46-cm) Schmidt telescope at Palomar Observatory in California. Its appearance was very unusual—it comprised at least a dozen active cometary nuclei lined up like glowing pearls on a string. As the nuclei spread farther apart, a total of 21 fragments were seen. An analysis of their common orbit revealed that the original comet had been revolving about the Sun and had been captured into orbit around Jupiter, most probably around 1929. It had passed only 0.31 Jupiter radii, about 22,100 km [13,800 miles], above the cloud tops of Jupiter’s atmosphere on July 8, 1992. At that distance, tidal forces from the giant planet’s gravity broke the original nucleus (estimated to be 1.6 km [1 mile] in diameter) into many pieces. The resulting 21 nuclei followed a highly eccentric two year orbit around Jupiter. Gravitational perturbations by the Sun then changed the orbit and lowered the perijove (point of closest approach to Jupiter) to less than the planet’s radius, causing the 21 nuclei to impact Jupiter in July 1994.
The train of fragments from Shoemaker-Levy 9 smashed into Jupiter’s atmosphere with a velocity of 221,000 km (137,300 miles) per hour beginning on July 16, 1994. They all hit on the unobservable night side beyond the limb of Jupiter as seen from Earth. Fortunately, NASA’s Galileo spacecraft, then en route to Jupiter, was in a position to see the night side and observed the impacts directly. For Earth-based observers, the planet’s 9.92-hour rotation period quickly brought each impact site into view. Separated in time by an average of seven to eight hours, each fragment plunged deep into the Jovian atmosphere, exploding with tremendous energy and creating a bubble of super-hot gas called a “fireball.” As the fireball rose back out of the Jovian atmosphere, it deposited dark clouds of ejecta on top of the Jovian clouds. aligned along a zone near latitude 44° S. Those clouds were composed of fine organic cometary dust and dust from the fireball burning in Jupiter’s atmosphere. About one-third of the fragments produced little or no observable effects, suggesting that their nuclei were very small, probably less than 100 metres (330 feet) in diameter.
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Astronomers labeled the individual fragments with capital letters in order of arrival. Fragment G, with an estimated diameter of 350–600 metres (1,100–2,000 feet), was probably the largest and heaviest. It left a multiringed black cloud larger than Earth’s diameter. Its impact delivered energy equivalent to at least 48 billion tons of TNT—many times the yield of the world’s supply of nuclear weapons. The dark clouds glowed warmly in infrared images of Jupiter as they slowly expanded and cooled over a few days, and they remained visible for weeks. They faded slowly and eventually disappeared.