Shoemaker-Levy 9

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D / 1993 F2 (Shoemaker-Levy) [i]
Shoemaker-Levy 9 on 1994-05-17.png
Comet Shoemaker-Levy 9, broken into 21 fragments, taken on May 17, 1994 with the Hubble Space Telescope
Properties of the orbit
Orbit type short-term
Numerical eccentricity 0.066
Perihelion 4.822 AU
Aphelion 5.503 AU
Major semi-axis 5.162 AU
Sidereal period 11 a 266 d
Inclination of the orbit plane 1.350 °
Perihelion none
Orbital velocity in the perihelion 14.003 km / s
Physical properties of the core
Medium diameter ≈ 4 km
Explorer CS Shoemaker ,
E. Shoemaker ,
D. Levy
Date of discovery March 24, 1993
Older name 1993 e
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

Shoemaker-Levy 9 (also SL9 for short ) was a comet discovered in 1993 . Its official name is D / 1993 F2 (Shoemaker-Levy). The "D" in its name stands for the English "disappeared" and indicates that the comet no longer exists. Its fragments plunged into the planet Jupiter in July 1994 . It got its name because it was the ninth short-period comet discovered by Carolyn and Eugene Shoemaker along with David H. Levy .


The comet was first identified in a photo taken on March 24, 1993 with a 46 cm Schmidt telescope at the Mount Palomar Observatory in California. The Japanese Shuichi Nakano was the first to predict the expected collision. The observation was subsequently confirmed by other astronomers . It quickly became clear that it was an unusual comet: it was apparently close to the planet Jupiter and had broken into several fragments.


The comet probably came under the strong gravitational forces of Jupiter as early as the 1960s and was thus forced into a highly elliptical orbit around the planet Jupiter as a quasi satellite . As a result, it passed Jupiter within the Roche limit in July 1992 . Due to the tidal forces , the comet, which originally had a diameter of around 4 km, broke into 21 fragments between 50 and 1000 m in size, which were lined up on a chain several million kilometers long. To distinguish them, the fragments were designated with the letters “A” to “W”. (The letters "I" and "O" were not used because of their similarity to the numbers "1" and "0".)

Due to its proximity to Jupiter, the comet's orbit was subject to major disturbances . The orbital elements given in the adjacent table describe the orbit of the comet in May 1993 from a heliocentric point of view: With a semi-major axis of 5.16  AU , an eccentricity of 0.07 and an orbit inclination of 1.4 °, the orbit was that of Jupiter ( major semiaxis 5.20; eccentricity 0.05; orbit inclination 1.3 °) very similar, especially since the comet was "captured" by Jupiter. From Jupiter's point of view, the comet moved on a strongly elliptical orbit (eccentricity greater than 0.99) at a distance of up to 0.33 AU around the planet.

Just two months after the discovery, astronomers' orbit determination showed that the comet pieces would collide with the planet Jupiter in July 1994.

Immersion in Jupiter

Impact of the fragment "W", recorded by the space probe Galileo ( NASA )
Dark spots in the atmosphere of the planet Jupiter after the submergence of the comet Shoemaker-Levy 9 (the point in the picture above is the Jupiter moon Io ), ultraviolet image from July 21, 1994 ( HST , NASA ).

Between July 16 and July 22, 1994, the fragments of Comet Shoemaker-Levy 9 struck Jupiter's southern hemisphere at a speed of 60 km / s, releasing the energy of 50 million Hiroshima bombs / 650  gigatons of TNT . This was the first time that the collision of two bodies in the solar system and the effects of such an impact could be observed directly.

Although the point of impact was just behind the "edge" of Jupiter from the earth's point of view and was therefore not directly visible, the astronomers could see so-called " plumes " (hot gas bubbles, similar to a " mushroom cloud ") rising over the edge of Jupiter. Due to the rapid rotation of Jupiter, the impact points became visible from Earth just a few minutes after the impacts. It was found that they had left dark spots with diameters up to 12,000 km in Jupiter's atmosphere that remained visible for months.

Only the Galileo space probe was able to observe the impacts directly from a distance of 1.6 AU. Due to a defective parabolic antenna, the space probe's capacity for data transmission was limited, and not all measured values ​​could be transmitted to earth. In addition, as a result of the Challenger catastrophe , Galileo was only sent to Jupiter three years later - if the launch date had been held in 1986, the space probe would have been able to follow the impacts in Jupiter's orbit at close range.

Large amounts of molecular sulfur (S 2 ) and carbon disulfide (CS 2 ) were found in the spectra of the plumes , more than could have been released by the explosion of a comparatively small cometary nucleus . One suspects the origin in deeper layers of the atmosphere of Jupiter. Other detected molecules are carbon monoxide (CO), ammonia (NH 3 ) and hydrogen sulfide (H 2 S). Also, emission lines of iron , magnesium and silicon were observed: The heat of the explosions must therefore have been sufficient to vaporize these metals. Water was observed in lower amounts than was initially expected. Presumably the water molecules were split up by the heat.

The collision was not only observed by astronomers, who this week exhausted almost every available means of observing Jupiter, but also followed with great interest in the mass media.

See also


Web links

Commons : Comet Shoemaker-Levy 9  - Collection of images, videos and audio files

Individual evidence

  1. ^ BG Marsden: IAU Circular 5725 .
  2. ^ RR Landis: Comet P / Shoemaker-Levy's Collision with Jupiter: Covering HST's Planned Observations from Your Planetarium. In: Proceedings of the International Planetarium Society Conference held at the Astronaut Memorial Planetarium & Observatory, Cocoa, Florida. Cocoa 1994, p. 10 ff.
  3. MD Zamarashkina, YD Medvedev: Estimation of the Nucleus Size of Comet Shoemaker-Levy 9 under the Assumption of Its Step-by-Step Disintegration. In: Solar System Research. Vol. 38, 2004, 3, p. 219 ff. Doi: 10.1023 / B: SOLS.0000030862.34790.4e , ISSN  0038-0946 .
  4. ^ BG Marsden: IAU Circular 5800.