23 July 1995

Comet Hale–Bopp is discovered; it becomes visible to the naked eye on Earth nearly a year later.

C/1995 O1 (Hale–Bopp)
Comet Hale-Bopp 1995O1.jpg
Comet Hale–Bopp, shortly after passing perihelion in April 1997
Discovered byAlan Hale
Thomas Bopp
Discovery dateJuly 23, 1995
The Great Comet of 1997,
C/1995 O1
Orbital characteristics A
Observation arc8.48 years
Orbit typeLong period comet
Aphelion370.8 AU[1]
Perihelion0.914 AU[2]
Semi-major axis186 AU
Orbital period2520[3]–2533[1] yr
(Barycentric 2391 yr)[4]
Dimensions40–80 km[1]
Nucleus albedo0.01–0.07
Last perihelionApril 1, 1997[2]
2215 BC[5]
Next perihelion4385 ± 2.0 AD[6]

Comet Hale–Bopp (formally designated C/1995 O1) is a comet that was perhaps the most widely observed of the 20th century and one of the brightest seen for many decades.

Alan Hale and Thomas Bopp discovered Comet Hale–Bopp separately on July 23, 1995, before it became visible to the naked eye. It is difficult to predict the maximum brightness of new comets with any degree of certainty, but Hale–Bopp met and exceeded most predictions when it passed perihelion on April 1, 1997, reaching about magnitude –1.8. It was visible to the naked eye for a record 18 months, twice as long as the Great Comet of 1811, the previous record holder. Accordingly, Hale–Bopp was dubbed the great comet of 1997.


The comet was discovered independently on July 23, 1995, by two observers, Alan Hale and Thomas Bopp, both in the United States.[7]

Hale had spent many hundreds of hours searching for comets without success, and was tracking known comets from his driveway in New Mexico when he chanced upon Hale–Bopp just after midnight. The comet had an apparent magnitude of 10.5 and lay near the globular cluster M70 in the constellation of Sagittarius.[8][9] Hale first established that there was no other deep-sky object near M70, and then consulted a directory of known comets, finding that none were known to be in this area of the sky. Once he had established that the object was moving relative to the background stars, he emailed the Central Bureau for Astronomical Telegrams, the clearing house for astronomical discoveries.[10]

Bopp did not own a telescope. He was out with friends near Stanfield, Arizona, observing star clusters and galaxies when he chanced across the comet while at the eyepiece of his friend's telescope. He realized he might have spotted something new when, like Hale, he checked his star maps to determine if any other deep-sky objects were known to be near M70, and found that there were none. He alerted the Central Bureau for Astronomical Telegrams through a Western Union telegram. Brian G. Marsden, who had run the bureau since 1968, laughed, "Nobody sends telegrams anymore. I mean, by the time that telegram got here, Alan Hale had already e-mailed us three times with updated coordinates."[11]

The following morning, it was confirmed that this was a new comet, and it was given the designation C/1995 O1. The discovery was announced in International Astronomical Union circular 6187.[8][12]

Early observation

Hale–Bopp's orbital position was calculated as 7.2 astronomical units (AU) from the Sun, placing it between Jupiter and Saturn and by far the greatest distance from Earth at which a comet had been discovered by amateurs.[13][14] Most comets at this distance are extremely faint, and show no discernible activity, but Hale–Bopp already had an observable coma.[8] A precovery image taken at the Anglo-Australian Telescope in 1993 was found to show the then-unnoticed comet some 13 AU from the Sun,[15] a distance at which most comets are essentially unobservable. (Halley's Comet was more than 100 times fainter at the same distance from the Sun.)[16] Analysis indicated later that its comet nucleus was 60±20 kilometres in diameter, approximately six times the size of Halley.[1][17]

Its great distance and surprising activity indicated that comet Hale–Bopp might become very bright when it reached perihelion in 1997. However, comet scientists were wary – comets can be extremely unpredictable, and many have large outbursts at great distance only to diminish in brightness later. Comet Kohoutek in 1973 had been touted as a 'comet of the century' and turned out to be unspectacular.[10]


The comet became a spectacular sight in early 1997.
Star map of path with 14-day motion marked

Hale–Bopp became visible to the naked eye in May 1996, and although its rate of brightening slowed considerably during the latter half of that year,[18] scientists were still cautiously optimistic that it would become very bright. It was too closely aligned with the Sun to be observable during December 1996, but when it reappeared in January 1997 it was already bright enough to be seen by anyone who looked for it, even from large cities with light-polluted skies.[19]

The Internet was a growing phenomenon at the time, and numerous websites that tracked the comet's progress and provided daily images from around the world became extremely popular. The Internet played a large role in encouraging the unprecedented public interest in comet Hale–Bopp.[20]

As the comet approached the Sun, it continued to brighten, shining at 2nd magnitude in February, and showing a growing pair of tails, the blue gas tail pointing straight away from the Sun and the yellowish dust tail curving away along its orbit. On March 9, a solar eclipse in China, Mongolia and eastern Siberia allowed observers there to see the comet in the daytime.[21] Hale–Bopp had its closest approach to Earth on March 22, 1997, at a distance of 1.315 AU.[22]

As it passed perihelion on April 1, 1997, the comet developed into a spectacular sight. It shone brighter than any star in the sky except Sirius, and its dust tail stretched 40–45 degrees across the sky.[23][24] The comet was visible well before the sky got fully dark each night, and while many great comets are very close to the Sun as they pass perihelion, comet Hale–Bopp was visible all night to northern hemisphere observers.[25]

After perihelion

After its perihelion passage, the comet moved into the southern celestial hemisphere. The comet was much less impressive to southern hemisphere observers than it had been in the northern hemisphere, but southerners were able to see the comet gradually fade from view during the second half of 1997. The last naked-eye observations were reported in December 1997, which meant that the comet had remained visible without aid for 569 days, or about 18 and a half months.[18] The previous record had been set by the Great Comet of 1811, which was visible to the naked eye for about 9 months.[18]

The comet continued to fade as it receded, but is still being tracked by astronomers. In October 2007, 10 years after the perihelion and at distance of 25.7 AU from Sun, the comet was still active as indicated by the detection of the CO-driven coma.[26] Herschel Space Observatory images taken in 2010 suggest comet Hale–Bopp is covered in a fresh frost layer.[27] Hale–Bopp was again detected in December 2010 when it was 30.7 AU away from the Sun,[28] and on August 7, 2012, at a 33.2 AU distance from the Sun.[29] Astronomers expect that the comet will remain observable with large telescopes until perhaps 2020, by which time it will be nearing 30th magnitude. By this time it will become very difficult to distinguish the comet from the large numbers of distant galaxies of similar brightness.[30]

Orbital changes

Hale–Bopp at perihelion on April 1, 1997
Animation of Hale-Bopp orbit
Polar view
Equatorial view
   Hale–Bopp  ·   Mercury ·   Venus  ·   Earth  ·   Mars  ·   Jupiter

The comet likely made its previous perihelion 4,200 years ago,[31] in July 2215 BC.[5] The estimated closest approach to Earth was 1.4 AU, and it may have been observed in ancient Egypt during the 6th dynasty reign of the Pharaoh Pepi II (Reign: 2247 – c. 2216 BC). Pepi's pyramid at Saqqara contains a text referring to an "nhh-star" as a companion of the pharaoh in the heavens, where "nhh" is the hieroglyph for long hair.[32]

Hale–Bopp may have had a near collision with Jupiter in early June 2215 BC, which probably caused a dramatic change in its orbit, and 2215 BC may have been its first passage through the inner Solar System from the Oort cloud.[5] The comet's current orbit is almost perpendicular to the plane of the ecliptic, so further close approaches to planets will be rare. However, in April 1996 the comet passed within 0.77 AU of Jupiter, close enough for its orbit to be measurably affected by the planet's gravity.[31] The comet's orbit was shortened considerably to a period of roughly 2,533 years,[1] and it will next return to the inner Solar System around the year 4385.[6] Its greatest distance from the Sun (aphelion) will be about 370 AU,[1] reduced from about 525 AU.[5][33]

The estimated probability of Hale-Bopp's striking Earth in future passages through the inner Solar System is remote, about 2.5×10−9 per orbit.[34] However, given that the comet nucleus is around 60 km in diameter,[1] the consequences of such an impact would be apocalyptic. Weissman conservatively estimates the diameter at 35 km; an estimated density of 0.6 g/cm3 then gives a cometary mass of 1.3×1019 g. At a probable impact velocity of 52.5 km/s, impact energy can be calculated as 1.9×1032 ergs, or 4.4×109 megatons, about 44 times the estimated energy of the K-T impact event.[34]

Over many orbits, the cumulative effect of gravitational perturbations on comets with high orbital inclinations and small perihelion distances is generally to reduce the perihelion distance to very small values. Hale–Bopp has about a 15% chance of eventually becoming a sungrazing comet through this process.[35]

Scientific results

Comet Hale–Bopp was observed intensively by astronomers during its perihelion passage, and several important advances in cometary science resulted from these observations. The dust production rate of the comet was very high (up to 2.0×106 kg/s),[36] which may have made the inner coma optically thick.[37] Based on the properties of the dust grains—high temperature, high albedo and strong 10 μm silicate emission feature—the astronomers concluded the dust grains are smaller than observed in any other comet.[38]

Hale–Bopp showed the highest ever linear polarization detected for any comet. Such polarization is the result of solar radiation getting scattered by the dust particles in the coma of the comet and depends on the nature of the grains. It further confirms that the dust grains in the coma of comet Hale–Bopp were smaller than inferred in any other comet.[39]

Sodium tail

Comet Hale–Bopp's neutral sodium tail (the straight tail extending up to the left from the nucleus)[40]

One of the most remarkable discoveries was that the comet had a third type of tail. In addition to the well-known gas and dust tails, Hale–Bopp also exhibited a faint sodium tail, only visible with powerful instruments with dedicated filters. Sodium emission had been previously observed in other comets, but had not been shown to come from a tail. Hale–Bopp's sodium tail consisted of neutral atoms (not ions), and extended to some 50 million kilometres in length.[40]

The source of the sodium appeared to be the inner coma, although not necessarily the nucleus. There are several possible mechanisms for generating a source of sodium atoms, including collisions between dust grains surrounding the nucleus, and "sputtering" of sodium from dust grains by ultraviolet light. It is not yet established which mechanism is primarily responsible for creating Hale–Bopp's sodium tail, and the narrow[40] and diffuse[41] components of the tail may have different origins.[42]

While the comet's dust tail roughly followed the path of the comet's orbit and the gas tail pointed almost directly away from the Sun, the sodium tail appeared to lie between the two. This implies that the sodium atoms are driven away from the comet's head by radiation pressure.[40]

Deuterium abundance

The abundance of deuterium in comet Hale–Bopp in the form of heavy water was found to be about twice that of Earth's oceans. If Hale–Bopp's deuterium abundance is typical of all comets, this implies that although cometary impacts are thought to be the source of a significant amount of the water on Earth, they cannot be the only source.[43]

Deuterium was also detected in many other hydrogen compounds in the comet. The ratio of deuterium to normal hydrogen was found to vary from compound to compound, which astronomers believe suggests that cometary ices were formed in interstellar clouds, rather than in the solar nebula. Theoretical modelling of ice formation in interstellar clouds suggests that comet Hale–Bopp formed at temperatures of around 25–45 kelvins.[43]


Spectroscopic observations of Hale–Bopp revealed the presence of many organic chemicals, several of which had never been detected in comets before. These complex molecules may exist within the cometary nucleus, or might be synthesised by reactions in the comet.[44]

Detection of argon

Hale–Bopp was the first comet where the noble gas argon was detected.[45] Noble gases are chemically inert and vary from low to high volatility. Since different noble elements have different sublimation temperatures, and don't interact with other elements, they can be used for probing the temperature histories of the cometary ices. Krypton has a sublimation temperature of 16–20 K and was found to be depleted more than 25 times relative to the solar abundance,[46] while argon with its higher sublimation temperature was enriched relative to the solar abundance.[45] Together these observations indicate that the interior of Hale–Bopp has always been colder than 35–40 K, but has at some point been warmer than 20 K. Unless the solar nebula was much colder and richer in argon than generally believed, this suggests that the comet formed beyond Neptune in the Kuiper belt region and then migrated outward to the Oort cloud.[45]


Comet Hale–Bopp's activity and outgassing were not spread uniformly over its nucleus, but instead came from several specific jets. Observations of the material streaming away from these jets[47] allowed astronomers to measure the rotation period of the comet, which was found to be about 11 hours 46 minutes.[48]

Binary nucleus question

In 1997 a paper was published that hypothesised the existence of a binary nucleus to fully explain the observed pattern of comet Hale–Bopp's dust emission observed in October 1995. The paper was based on theoretical analysis, and did not claim an observational detection of the proposed satellite nucleus, but estimated that it would have a diameter of about 30 km, with the main nucleus being about 70 km across, and would orbit in about three days at a distance of about 180 km.[49] This analysis was confirmed by observations in 1996 using Wide-Field Planetary Camera 2 of the Hubble Space Telescope which had taken images of the comet that revealed the satellite.[50]

Although observations using adaptive optics in late 1997 and early 1998 showed a double peak in the brightness of the nucleus,[51] controversy still exists over whether such observations can only be explained by a binary nucleus.[17] The discovery of the satellite was not confirmed by other observations.[52][53] Also, while comets have been observed to break up before,[54] no case had been found of a stable binary nucleus until the subsequent discovery of P/2006 VW139.

UFO claims

In November 1996, amateur astronomer Chuck Shramek (1950–2000) of Houston, Texas took a CCD image of the comet which showed a fuzzy, slightly elongated object nearby. His computer sky-viewing program did not identify the star, so Shramek called the Art Bell radio program Coast to Coast AM to announce that he had discovered a "Saturn-like object" following Hale–Bopp. UFO enthusiasts such as remote viewing proponent, and Emory University political science professor Courtney Brown soon concluded that there was an alien spacecraft following the comet.[55]

Several astronomers claimed that the object was simply the 8.5-magnitude star SAO141894, including Alan Hale.[56] They noted that the star did not appear on Shramek's computer program because the user preferences were set incorrectly.[57] Art Bell claimed to have obtained an image of the object from an anonymous astrophysicist who was about to confirm its discovery. However, astronomers Olivier Hainaut and David Tholen of the University of Hawaii stated that the alleged photo was an altered copy of one of their own comet images.[58]

Thirty-nine members of the Heaven's Gate cult committed mass suicide in March 1997 with the intention of teleporting to a spaceship which they believed was flying behind the comet.[59]

Nancy Lieder, who claims to receive messages from aliens through an implant in her brain, stated that Hale–Bopp was a fiction designed to distract the population from the coming arrival of "Nibiru" or "Planet X", a giant planet whose close passage would disrupt the Earth's rotation, causing global cataclysm.[60] Her original date for the apocalypse was May 2003, which passed without incident, but various conspiracy websites continued to predict the coming of Nibiru, most of whom tied it to the 2012 phenomenon.[61] Lieder and others' claims of the planet Nibiru have been repeatedly debunked by scientists.[62]


Comet Hale–Bopp in 2001, at a distance of nearly two billion kilometres from the Sun. Credit: ESO

Its lengthy period of visibility and extensive coverage in the media meant that Hale–Bopp was probably the most-observed comet in history, making a far greater impact on the general public than the return of Halley's Comet in 1986, and certainly seen by a greater number of people than witnessed any of Halley's previous appearances. For instance, 69% of Americans had seen Hale–Bopp by April 9, 1997.[63]

Hale–Bopp was a record-breaking comet—the farthest comet from the Sun discovered by amateurs,[22] with the largest well-measured cometary nucleus known after 95P/Chiron,[17] and it was visible to the naked eye for twice as long as the previous record-holder.[18] It was also brighter than magnitude 0 for eight weeks, longer than any other recorded comet.[22]

Carolyn Shoemaker and her husband Gene, both famous for co-discovering comet Shoemaker–Levy 9, were involved in a car crash after photographing the comet. Gene died in the crash and his ashes were sent to the Moon aboard NASA's Lunar Prospector mission along with an image of Hale–Bopp, "the last comet that the Shoemakers observed together".[64]

See also


  1. ^ a b c d e f g "JPL Small-Body Database Browser: C/1995 O1 (Hale–Bopp)" (2007-10-22 last obs). Retrieved December 5, 2008.
  2. ^ a b JPL SBDB Epoch 1996
  3. ^ Syuichi Nakano (February 12, 2008). "OAA computing section circular NK 1553". OAA Computing and Minor Planet Sections. Retrieved December 17, 2009.
  4. ^ Horizons output. "Barycentric Osculating Orbital Elements for Comet C/1995 O1 (Hale-Bopp)". Retrieved January 31, 2011. (Solution using the Solar System Barycenter and barycentric coordinates. Select Ephemeris Type:Elements and Center:@0)
  5. ^ a b c d Marsden, B. G. (1997). "Orbit Determination and Evolution of Comet C/1995 O1 (Hale-Bopp)". Earth, Moon, and Planets. 79 (1): 3–15. Bibcode:1997EM&P...79....3M. doi:10.1023/A:1006268813208. S2CID 121368997.
  6. ^ a b "Solex 10 estimate for Next Perihelion of C/1995 O1 (Hale-Bopp)". Archived from the original on August 10, 2012. Retrieved December 18, 2009.
  7. ^ Shanklin, Jonathan D. (2000). "The comets of 1995". Journal of the British Astronomical Association. 110 (6): 311. Bibcode:2000JBAA..110..311S.
  8. ^ a b c Hale, A.; Bopp, T.; Stevens, J. (July 23, 1995). "IAU Circular No. 6187". IAU. Retrieved July 5, 2011.
  9. ^ Mobberley, Martin (2013), It Came From Outer Space Wearing an RAF Blazer!: A Fan's Biography of Sir Patrick Moore, Springer Science & Business Media, p. 483, ISBN 978-3319006093
  10. ^ a b Lemonick, Michael D. (March 17, 1997). "Comet of the decade Part II". Time. Retrieved October 30, 2008.
  11. ^ Newcott, William (December 1997). "The Age of Comets". National Geographic Society. Retrieved December 7, 2009. Nobody sends telegrams anymore...
  12. ^ Bopp, Thomas (1997). "Amateur Contributions in the study of Comet Hale–Bopp". Earth, Moon, and Planets. 79 (1–3): 307–308. Bibcode:1997EM&P...79..307B. doi:10.1023/A:1006262006364. S2CID 117124838.
  13. ^ Marsden, B. G. (1995). "Comet C/1995 O1 (Hale-Bopp)". Minor Planet Electronic Circular. 1995-P05.
  14. ^ Kidger, M. R.; Serra-Ricart, Miquel; Bellot-Rubio, Luis R.; Casas, Ricard (1996). "Evolution of a Spiral Jet in the Inner Coma of Comet Hale-Bopp (1995 O1)". The Astrophysical Journal Letters. 461 (2): L119–L122. Bibcode:1996ApJ...461L.119K. doi:10.1086/310008.
  15. ^ McNaught, R. H.; West, R. M. (August 2, 1995). "Circular No. 6198". IAU. Retrieved July 5, 2011.
  16. ^ Biver, N.; Rauer, H; Despois, D; Moreno, R; Paubert, G; Bockelée-Morvan, D; Colom, P; Crovisier, J; et al. (1996). "Substantial outgassing of CO from Comet Hale–Bopp at large heliocentric distance". Nature. 380 (6570): 137–139. Bibcode:1996Natur.380..137B. doi:10.1038/380137a0. PMID 8600385. S2CID 4342525.
  17. ^ a b c Fernández, Yanga R. (2002). "The Nucleus of Comet Hale-Bopp (C/1995 O1): Size and Activity". Earth, Moon, and Planets. 89 (1): 3–25. Bibcode:2002EM&P...89....3F. doi:10.1023/A:1021545031431. S2CID 189899565.
  18. ^ a b c d Kidger, M.R.; Hurst, G.; James, N. (2004). "The Visual Light Curve Of C/1995 O1 (Hale-Bopp) From Discovery To Late 1997". Earth, Moon, and Planets. 78 (1–3): 169–177. Bibcode:1997EM&P...78..169K. doi:10.1023/A:1006228113533. S2CID 120776226.
  19. ^ Browne, Malcolm R. (March 9, 1997). "Comet Holds Clues to Birth of Time". The New York Times.
  20. ^ "The Trail of Hale-Bopp". Scientific American. March 17, 1997. Retrieved October 23, 2008.
  21. ^ McGee, H. W.; Poitevin, P. (1997). "The total solar eclipse of 1997 March 9". Journal of the British Astronomical Association. 107 (3): 112–113. Bibcode:1997JBAA..107..112M.
  22. ^ a b c "Comet Hale-Bopp". Stardust. Jet Propulsion Laboratory, NASA. November 26, 2003. Retrieved October 9, 2008.
  23. ^ West, Richard M. (April 13, 1997). "Comet Hale-Bopp (April 13, 1997)". European Southern Observatory. Archived from the original on May 24, 2011. Retrieved November 23, 2008.
  24. ^ Shylaja, B. S. (1997). "What's New With Hale Bopp?". Bulletin of the Astronomical Society of India. 25: 155–156. Bibcode:1997BASI...25..155S.
  25. ^ West, Richard M. (March 7, 1997). "Comet Hale-Bopp (March 7, 1997)". European Southern Observatory. Archived from the original on May 24, 2011. Retrieved November 25, 2008.
  26. ^ Szabó, Gy. M.; Kiss, L. L.; Sárneczky, K. (2008). "Cometary Activity at 25.7 AU: Hale-Bopp 11 Years after Perihelion". Astrophysical Journal Letters. 677 (2): 121. arXiv:0803.1505. Bibcode:2008ApJ...677L.121S. doi:10.1086/588095. S2CID 13344162.
  27. ^ Szabó, Gy. M.; Kiss, L. L.; Kiss, Cs.; Pál, A.; Sárneczky, K.; Juhász, A.; Hogerheijde, M. R. (2012). "Evidence for fresh frost layer on the bare nucleus of comet Hale—Bopp at 32 AU distance". Astrophysical Journal. 761 (1): 8. arXiv:1210.2785. Bibcode:2012ApJ...761....8S. doi:10.1088/0004-637X/761/1/8. S2CID 119197339.
  28. ^ Szabó, M.; Sárneczky, K.; Kiss, L. L. (2011). "Frozen to death? – Detection of comet Hale-Bopp at 30.7 AU". Earth and Planetary Astrophysics. 1104: 4351. arXiv:1104.4351. Bibcode:2011A&A...531A..11S. doi:10.1051/0004-6361/201116793. S2CID 119113598.
  29. ^ Dave Herald (August 7, 2012). "Comet Hale-Bopp C/1995 O1 - observed tonite". Yahoo Groups. Retrieved August 9, 2012.
  30. ^ West, Richard M. (February 7, 1997). "Comet Hale-Bopp (February 7, 1997)". European Southern Observatory. Archived from the original on January 12, 2015. Retrieved January 12, 2015.
  31. ^ a b Yeomans, Don (April 10, 1997). "Comet Hale-Bopp Orbit and Ephemeris Information". JPL/NASA. Retrieved October 23, 2008.
  32. ^ "The Lost Tomb", Kent Weeks, ISBN 0-297-81847-3, page 198
  33. ^ Williams, David R. (December 23, 2005). "Comet Fact Sheet". NASA (National Space Science Data Center). Retrieved December 5, 2008. (pre-perturbation orbit: semi-major axis 250AU; period 4000yr)
  34. ^ a b Weissman, Paul R. (2007). "The cometary impactor flux at the Earth". Proceedings of the International Astronomical Union. Cambridge University Press. 2 (S236): 441–450. Bibcode:2007IAUS..236..441W. doi:10.1017/S1743921307003559. ISBN 978-0-521-86345-2.
  35. ^ Bailey, M. E.; Emel'Yanenko, V. V.; Hahn, G.; Harris, N. W.; Hughes, K. A.; Muinonen, K.; Scotti, J. V. (1996). "Orbit Determination and Evolution of Comet C/1995 O1 (Hale-Bopp)". Monthly Notices of the Royal Astronomical Society. 281 (1): 916–924. Bibcode:1996MNRAS.281..916B. CiteSeerX doi:10.1093/mnras/281.3.916.
  36. ^ Jewitt, David; Matthews, Henry (1999). "Particulate Mass Loss from Comet Hale-Bopp". The Astronomical Journal. 117 (2): 1056–1062. Bibcode:1999AJ....117.1056J. doi:10.1086/300743. S2CID 120740179.
  37. ^ Fernández, Yanga R.; Wellnitz, Dennis D.; Buie, Marc W.; Dunham, Edward W.; Millis, Robert L.; Nye, Ralph A.; Stansberry, John A.; Wasserman, Lawrence H.; a'Hearn, Michael F.; Lisse, Carey M.; Golden, Meg E.; Person, Michael J.; Howell, Robert R.; Marcialis, Robert L.; Spitale, Joseph N. (1999). "The Inner Coma and Nucleus of Comet Hale–Bopp: Results from a Stellar Occultation". Icarus. 140 (1): 205–220. Bibcode:1999Icar..140..205F. doi:10.1006/icar.1999.6127. S2CID 43229796.
  38. ^ Mason, C. G.; Gehrz, R. D.; Jones, T. J.; Woodward, C E.; Hanner, M. S.; Williams, D. M. (2001). "Observations of Unusually Small Dust Grains in the Coma of Comet Hale-Bopp C/1995 O1". The Astrophysical Journal. 549 (1): 635–646. Bibcode:2001ApJ...549..635M. doi:10.1086/319039.
  39. ^ Ganesh, S.; Joshi, U. C.; Baliyan, K. S.; Deshpande, M. R. (1998). "Polarimetric observations of the comet Hale-Bopp". Astronomy and Astrophysics Supplement. 129 (5): 489–493. Bibcode:1998A&AS..129..489G. doi:10.1051/aas:1998201.
  40. ^ a b c d Cremonese, G; Boehnhardt, H; Crovisier, J; Rauer, H; Fitzsimmons, A; Fulle, M; Licandro, J; Pollacco, D; et al. (1997). "Neutral Sodium from Comet Hale–Bopp: A Third Type of Tail". The Astrophysical Journal Letters. 490 (2): L199–L202. arXiv:astro-ph/9710022. Bibcode:1997ApJ...490L.199C. doi:10.1086/311040. S2CID 119405749.
  41. ^ Wilson, J. K.; Baumgardner, J.; Mendillo, M. (1998). "Three tails of comet Hale-Bopp". Geophysical Research Letters. 25 (3): 225–228. Bibcode:1998GeoRL..25..225W. doi:10.1029/97GL03704.
  42. ^ Cremonese, G.; Fulle, Marco (1997). "Sodium In Comets". Earth, Moon, and Planets. 79 (1): 209–220. Bibcode:1997EM&P...79..209C. doi:10.1023/A:1006245619568. S2CID 118693620.
  43. ^ a b Meier, Roland; Owen, Tobias C. (1999). "Cometary Deuterium". Space Science Reviews. 90 (1–2): 33–43. Bibcode:1999SSRv...90...33M. doi:10.1023/A:1005269208310. PMID 11543290. S2CID 34317575.
  44. ^ Rodgers, S. D.; Charnley, S. B. (2002). "Organic synthesis in the coma of Comet Hale–Bopp?". Monthly Notices of the Royal Astronomical Society. 320 (4): L61–L64. Bibcode:2001MNRAS.320L..61R. doi:10.1046/j.1365-8711.2001.04208.x.
  45. ^ a b c Stern, S. A.; Slater, D. C.; Festou, M. C.; Parker, J. Wm.; Gladstone, G. R.; A'hearn, M. F.; Wilkinson, E. (2000). "The Discovery of Argon in Comet C/1995 O1 (Hale-Bopp)". The Astrophysical Journal. 544 (2): L169–L172. arXiv:astro-ph/0011327. Bibcode:2000ApJ...544L.169S. doi:10.1086/317312. S2CID 16759616.
  46. ^ Krasnopolsky, Vladimir A.; Mumma, MJ; Abbott, M; Flynn, BC; Meech, KJ; Yeomans, DK; Feldman, PD; Cosmovici, CB (1997). "Detection of Soft X-rays and a Sensitive Search for Noble Gases in Comet Hale-Bopp (C/1995 O1)". Science. 277 (5331): 1488–1491. Bibcode:1997Sci...277.1488K. doi:10.1126/science.277.5331.1488. PMID 9278508.
  47. ^ "Bergeron Comet Hale-Bopp Animation". Stardust. Jet Propulsion Laboratory, NASA. Retrieved October 14, 2008.
  48. ^ Warell, J.; Lagerkvist, C.-I.; Lagerros, J. S. V. (1999). "Dust continuum imaging of C/1995 O1 (Hale-Bopp): Rotation period and dust outflow velocity". Astronomy and Astrophysics Supplement Series. 136 (2): 245–256. Bibcode:1999A&AS..136..245W. doi:10.1051/aas:1999213.
  49. ^ Sekanina, Z. (1997). "Detection of a Satellite Orbiting The Nucleus of Comet Hale–Bopp (C/1995 O1)". Earth, Moon, and Planets. 77 (3): 155–163. Bibcode:1997EM&P...77..155S. doi:10.1023/A:1006230712665. S2CID 122481110.
  50. ^ Sekanina, Z. (1998). "Detection of a Satellite orbiting the Nucleus of Comet Hale-Bopp (C/1995 O1)". Proceedings of the First International Conference on Comet Hale-Bopp. European Organisation for Astronomical Research in the Southern Hemisphere. 77 (3): 155–163. Bibcode:1997EM&P...77..155S. doi:10.1023/A:1006230712665. S2CID 122481110.
  51. ^ Marchis, F.; Boehnhardt, H.; Hainaut, O. R.; Le Mignant, D. (1999). "Adaptive optics observations of the innermost coma of C/1995 O1. Are there a "Hale" and a "Bopp" in comet Hale-Bopp?" (PDF). Astronomy & Astrophysics. 349: 985–995. Bibcode:1999A&A...349..985M. Archived from the original (PDF) on October 31, 2008. Retrieved October 29, 2008.
  52. ^ McCarthy, D. W.; Stolovy, S; Campins, H; Larson, S; Samarasinha, N; Kern, S (2007). "Comet Hale–Bopp in outburst: Imaging the dynamics of icy particles with HST/NICMOS". Icarus. 189 (1): 184–195. Bibcode:2007Icar..189..184M. doi:10.1016/j.icarus.2007.01.019.
  53. ^ Weaver, H. A.; Feldman, P. D.; a'Hearn, M. F.; Arpigny, C.; Brandt, J. C.; Stern, S. A. (1999). "Post-Perihelion HST Observations of Comet Hale–Bopp (C/1995 O1)". Icarus. 141 (1): 1–12. Bibcode:1999Icar..141....1W. doi:10.1006/icar.1999.6159.
  54. ^ Sekanina, Z. (1997). "The problem of split comets revisited". Astronomy and Astrophysics Letters. 318: L5–L8. Bibcode:1997A&A...318L...5S.
  55. ^ Jaroff, Leon; Willwerth, James (April 14, 1997). "The man who spread the myth". Time. Retrieved October 30, 2008.
  56. ^ Hale, Alan (1997). "Hale-Bopp Comet Madness". Skeptical Inquirer. 21 (2): 25–28. Archived from the original on February 8, 2010. Retrieved December 6, 2009.
  57. ^ Burnham, Robert; Levy, David H. (2000). Great Comets. Cambridge University Press. p. 191. ISBN 978-0-521-64600-0.
  58. ^ Tholen, David J. (January 15, 1997). "Fraudulent use of an IfA/UH picture". European Organisation for Astronomical Research in the Southern Hemisphere. Archived from the original on September 30, 2007. Retrieved October 14, 2008.
  59. ^ Robinson, Wendy Gale (2006). "Heaven's Gate: The End". Journal of Computer-Mediated Communication. 3 (3). doi:10.1111/j.1083-6101.1997.tb00077.x.
  60. ^ George Johnson (March 28, 1997). "Comets Breed Fear, Fascination and Web Sites". The New York Times. Retrieved September 27, 2009.
  61. ^ David Morrison. "The Myth of Nibiru and the End of the World in 2012". Skeptical Inquirer. Archived from the original on April 21, 2009. Retrieved April 28, 2009.
  62. ^ "Nibiru: The Nonexistent Planet". Space.com. December 4, 2018. Retrieved July 17, 2020.
  63. ^ Aguirre, Edwin L. (July 1997). "The Great Comet of 1997". Sky and Telescope.
  64. ^ "Eugene Shoemaker Ashes Carried on Lunar Prospector". www2.jpl.nasa.gov.

External links

25 March 1995

WikiWikiWeb, the world’s first wiki is made public by Ward Cunningham.

The history of wikis is generally dated from 1994, when Ward Cunningham gave the name “WikiWikiWeb” to the knowledge base, which ran on his company’s website at c2.com, and the wiki software that powered it. c2.com thus became the first true wiki, or a website with pages and links that can be easily edited via the browser, with a reliable version history for each page. He chose “WikiWikiWeb” as the name based on his memories of the “Wiki Wiki Shuttle” at Honolulu International Airport, and because “wiki” is the Hawaiian word for “quick”.

Wiki software has some conceptual origins in the version control and hypertext systems used for documentation and software in the 1980s, and some actualized origins in the 1970s “Journal” feature of NLS. Its distant ancestors include Vannevar Bush’s proposed “memex” system in 1945, the collaborative hypertext database ZOG in 1972, the NoteCards system from Xerox, the Apple hypertext system HyperCard. As was typical of these earlier systems, Cunningham’s motive was technical: to facilitate communication between software developers.

Many alternative wiki applications and websites appeared over the next five years. In the meantime, the first wiki, now known as “WardsWiki”, evolved as features were added to the software and as the growing body of users developed a unique “wiki culture”. By 2000, WardsWiki had developed a great deal of content outside its original stated purpose, which led to the spinoff of content into sister sites, most notably MeatballWiki.

The website Wikipedia, a free content encyclopedia, was launched in January 2001, and quickly became the most popular wiki, which it remains to this day. Its meteoric rise in popularity played a large part in introducing wikis to the general public. There now exist at least hundreds of thousands of wiki websites, and they have become increasingly prevalent in corporations and other organizations.

A distant precursor of the wiki concept was Vannevar Bush’s vision of the “memex,” a microfilm reader which would create automated links between documents. In a 1945 essay in Atlantic Monthly titled “As We May Think,” Bush described an imaginary future user interface: “Before him are the two items to be joined, projected onto adjacent viewing positions… The user taps a single key, and the items are permanently joined… Thereafter, at any time, when one of these items is in view, the other can be instantly recalled merely by tapping a button below the corresponding code space. Moreover, when numerous items have been thus joined together to form a trail, they can be reviewed in turn…” This vision, though it has been described as predicting the World Wide Web, resembles wikis more than the web in one important way: the system being described is self-contained, not a loose network.

In 1972 Kristo Ivanov published a PhD dissertation on Quality-control of information, containing a theoretical basis for what corresponds to the wiki-idea, in terms of systemic social interaction. Information turns into knowledge as a net of contributions and negotiations converge about a core concept, or entity. The emphasis is on a dynamically documented “agreement in the context of maximum possible disagreement,” akin to the discussions in talk pages and the results of view history of Wikipedia.

An indirect precursor of the wiki concept was the ZOG multi-user database system, developed in 1972 by researchers at Carnegie-Mellon University. The ZOG interface consisted of text-only frames, each containing a title, a description, a line with standard ZOG commands, and a set of selections leading to other frames.

Two members of the ZOG team, Donald McCracken and Robert Akscyn, spun off a company from CMU in 1981 and developed an improved version of ZOG called Knowledge Management System. KMS was a collaborative tool based on direct manipulation, permitting users to modify the contents of frames, freely intermixing text, graphics and images, any of which could be linked to other frames. Because the database was distributed and accessible from any workstation on a network, changes became visible immediately to other users, enabling them to work concurrently on shared structures.

Three notable hypertext-based systems emerged in the 1980s, that may have been inspired by ZOG, KMS and/or one another: the NoteCards system, developed in 1984 and released by Xerox in 1985; Janet Walker’s Symbolics Document Examiner, created in 1985 for the operation manuals of Symbolics computers; and Bill Atkinson’s WildCard application, on which he began work in 1985, and which was released in 1987 as HyperCard. Ward Cunningham has stated, that the wiki idea was influenced by his experience using HyperCard: he was shown the software by fellow programmer Kent Beck, before its official release, and, in his words, was “blown away” by it.

Cunningham used HyperCard to make a stack holding three kinds of information: ideas, people who hold ideas, and projects where people share ideas. He would later use this same architecture for the Patterns, People and Projects listed on the front page of his original wiki, the WikiWikiWeb Cunningham made a single card that would serve for all uses. It had three fields: Name, Description and Links. Cunningham configured the system so that links could be created to cards that didn’t exist yet; creating such a link would in turn create a new blank card.

In 1990, Tim Berners-Lee of CERN built the first hypertext client, which he called World Wide Web, and the first hypertext server. In 1991 he posted a short summary of the World Wide Web project on the alt.hypertext newsgroup, marking the debut of the Web as a publicly available service on the Internet.

Early adopters of the World Wide Web were primarily university-based scientific departments or physics laboratories. In May 1992 appeared ViolaWWW, a graphical browser providing features such as embedded graphics, scripting, and animation. However, the turning point for the World Wide Web was the introduction of the Mosaic graphical browser in 1993, which gained wide popularity due to its strong support of integrated multimedia. In April 1994, CERN agreed that anyone could use the Web protocol and code for free.

Ward Cunningham started developing the WikiWikiWeb in 1994 as a supplement to the Portland Pattern Repository, a website containing documentation about Design Patterns, a particular approach to object-oriented programming.

The WikiWikiWeb was intended as a collaborative database, in order to make the exchange of ideas between programmers easier; it was dedicated to “People, Projects and Patterns.” Cunningham wrote the software to run it using the Perl programming language. He considered calling the software “quick-web,” but instead named it using the Hawaiian word “wiki-wiki,” which means “quick-quick” or “very quick,” based on his memory of the Wiki Wiki Shuttle at Honolulu International Airport.

Cunningham installed a prototype of the software on his company Cunningham & Cunningham’s website c2.com. On March 16, 1995, when the site was functioning, Cunningham sent to a colleague the following email:

Steve – I’ve put up a new database on my web server and I’d like you to take a look. It’s a web of people, projects and patterns accessed through a cgi-bin script. It has a forms-based authoring capability that doesn’t require familiarity with html. I’d be very pleased if you would get on and at least enter your name in RecentVisitors. I’m asking you because I think you might also add some interesting content. I’m going to advertise this a little more widely in a week or so. The URL is http://c2.com/cgi-bin/wiki. Thanks and best regards. – Ward

Cunningham dates the official start of WikiWikiWeb as March 25, 1995. On May 1, 1995 he sent an email about the website to a number of programmers, which caused an increase in participation. This note was posted to the “Patterns” listserv, a group of software developers gathered under the name “The Hillside Group” to develop Erich Gamma’s use of object-oriented patterns. Cunningham had noticed that the older contents of the listserv tended to get buried under the more recent posts, and he proposed instead to collect ideas in a set of pages which would be collectively edited. Cunningham’s post stated: “The plan is to have interested parties write web pages about the People, Projects and Patterns that have changed the way they program.” He added: “Think of it as a moderated list where anyone can be moderator and everything is archived. It’s not quite a chat, still, conversation is possible.”

The site was immediately popular within the pattern community.

Ward Cunningham started developing the WikiWikiWeb in 1994 as a supplement to the Portland Pattern Repository, a website containing documentation about Design Patterns, a particular approach to object-oriented programming.

The WikiWikiWeb was intended as a collaborative database, in order to make the exchange of ideas between programmers easier; it was dedicated to “People, Projects and Patterns.” Cunningham wrote the software to run it using the Perl programming language. He considered calling the software “quick-web,” but instead named it using the Hawaiian word “wiki-wiki,” which means “quick-quick” or “very quick,” based on his memory of the Wiki Wiki Shuttle at Honolulu International Airport.

Cunningham installed a prototype of the software on his company Cunningham & Cunningham’s website c2.com. On March 16, 1995, when the site was functioning, Cunningham sent to a colleague the following email:

Steve – I’ve put up a new database on my web server and I’d like you to take a look. It’s a web of people, projects and patterns accessed through a cgi-bin script. It has a forms-based authoring capability that doesn’t require familiarity with html. I’d be very pleased if you would get on and at least enter your name in RecentVisitors. I’m asking you because I think you might also add some interesting content. I’m going to advertise this a little more widely in a week or so. The URL is http://c2.com/cgi-bin/wiki. Thanks and best regards. – Ward

Cunningham dates the official start of WikiWikiWeb as March 25, 1995. On May 1, 1995 he sent an email about the website to a number of programmers, which caused an increase in participation. This note was posted to the “Patterns” listserv, a group of software developers gathered under the name “The Hillside Group” to develop Erich Gamma’s use of object-oriented patterns. Cunningham had noticed that the older contents of the listserv tended to get buried under the more recent posts, and he proposed instead to collect ideas in a set of pages which would be collectively edited. Cunningham’s post stated: “The plan is to have interested parties write web pages about the People, Projects and Patterns that have changed the way they program.” He added: “Think of it as a moderated list where anyone can be moderator and everything is archived. It’s not quite a chat, still, conversation is possible.”

The site was immediately popular within the pattern community.

Among Cunningham’s innovations in creating WikiWikiWeb was the ability to easily link internally between pages; something that was often cumbersome to do in previous intranet and document management systems. Cunningham’s solution to this was to automatically link any text expressed in CamelCase; including text for which a corresponding page didn’t yet exist.

This CamelCase convention was used by most wiki software for the first few years of wikis’ existence. In 2001, the software UseModWiki, which at the time was in use on Wikipedia, switched to allow internal links to be done using standard spelling and double square bracket instead, in order to improve Wikipedia’s usability. This square bracket syntax has since become more of a default convention for internal links within wiki software in general.

Ward Cunningham wrote a version of his wiki software meant for public usage, called “Wiki Base”. In his announcement, he wrote: “WikiWikiWeb is almost public. Actually, a pretty good clone of it is public at: http://c2.com/cgi/wikibase. I’ve translated almost all of the actual wiki script into HyperPerl, a wiki-literate programming system that I think you will like.” Visitors were requested to register on the wiki before they took the Wiki Base code. Cunningham expected users to fold changes back into his editable version, but those who implemented changes generally chose to distribute the modified versions on their own sites.

Alternate applications for wikis began to emerge, usually imitating the look-and-feel of WikiWikiWeb/Wiki Base; such applications were originally known as “WikiWikiClones.” The first one was most likely created by IBM programmer Patrick Mueller, who wrote his in the REXX language, even before Wiki Base was released.

Inspired by the example of the WikiWikiWeb, programmers soon started several other wikis to build knowledge bases about programming topics. Wikis became popular in the free and open-source software community, where they were used for collaboratively discussing and documenting software. However, being used only by specialists, these early software-focused wikis failed to attract widespread public attention.

The WikiWikiWeb website approximately doubled in size every year 1995 to 2000, with disk usage rising from around 2 megabytes in 1995 to around 60 megabytes at the end of 2000. During that time, various innovations were put in place, many suggested by users, to help with navigation and editing. These included:

1995 – RecentVisitors, PeopleIndex: pages to help users know who was contributing
1995 – NotSoRecentChanges: excess lines from the RecentChanges page were copied to a file of “ChangesIn”
1996 – EditCopy: offers the possibility to edit the backup copy of a page this was replaced in 2002 with Page History
1996 – ThreadMode: the form of a page where community members hold a discussion, each signing their own contribution
1996 – WikiCategories: categories can be added as an automatic index to pages
1997 – RoadMaps: proposed lists of pages to consult about specific topics, such as the Algorithms RoadMap or the Leadership RoadMap
1999 – ChangeSummary: an aid to telling which changes added interesting new content and which were only minor
2000 – UserName: the Wiki will accept a cookie that specifies a User Name to be used in place of the host name in the RecentChanges log

“ThreadMode” was defined as “a form of discussion where our community holds a conversation.” It consists of a series of signed comments added down the page in chronological order. Ward Cunningham generally frowned on ThreadMode, writing: “Chronological is only one of many possible organizations of technical writing and rarely the best one at that.”

Cunningham encouraged contributors to “refactor” the ThreadMode discussions into DocumentMode discourse. In practice many pages started out at the top in DocumentMode and degenerated into ThreadMode further down. When ThreadMode became incomprehensible the result was called “ThreadMess.”

The use of categories was proposed by user Stan Silver on August 27, 1996. His initial post suggested: “If everyone adds a category and topic to their page, then the category and topic pages themselves can be used as automatic indexes into the pages.” Initially Silver had proposed both categories and topics: categories denoted the specific nature of the page’s subject, while topics denoted the theme of the page. However, people ignored this separation, and topics were collapsed into the categories.

The “ChangeSummary” option began as an aid to telling which changes added interesting new content, and which were just minor adjustments of spelling, punctuation, or correction of web links. It started when some users began taking the RecentChanges page, annotating each line with a brief description of each change, and posting the result to the ChangeSummary page. This practice was highly time-consuming and rapidly petered out, but was replaced by the “MinorEdit/RecentEdits” feature, designed to reduce the RecentChanges clutter.

1 January 1995

The World Trade Organization comes into existence.

The World Trade Organization is an intergovernmental organization that regulates international trade. The WTO officially commenced on 1 January 1995 under the Marrakesh Agreement, signed by 124 nations on 15 April 1994, replacing the General Agreement on Tariffs and Trade, which commenced in 1948. It is the largest international economic organization in the world.

The WTO deals with regulation of trade in goods, services and intellectual property between participating countries by providing a framework for negotiating trade agreements and a dispute resolution process aimed at enforcing participants’ adherence to WTO agreements, which are signed by representatives of member governments:fol.9–10 and ratified by their parliaments. The WTO prohibits discrimination between trading partners, but provides exceptions for environmental protection, national security, and other important goals. Trade-related disputes are resolved by independent judges at the WTO through a dispute resolution process.

The WTO’s current Director-General is Roberto Azevêdo, who leads a staff of over 600 people in Geneva, Switzerland. A trade facilitation agreement, part of the Bali Package of decisions, was agreed by all members on 7 December 2013, the first comprehensive agreement in the organization’s history. On 23 January 2017, the amendment to the WTO Trade Related Aspects of Intellectual Property Rights Agreement marks the first time since the organization opened in 1995 that WTO accords have been amended, and this change should secure for developing countries a legal pathway to access affordable remedies under WTO rules.

Studies show that the WTO boosted trade, and that barriers to trade would be higher in the absence of the WTO. The WTO has highly influenced the text of trade agreements, as “nearly all recent [preferential trade agreements reference the WTO explicitly, often dozens of times across multiple chapters… in many of these same PTAs we find that substantial portions of treaty language—sometime the majority of a chapter—is copied verbatim from a WTO agreement.”

The WTO’s predecessor, the General Agreement on Tariffs and Trade, was established by a multilateral treaty of 23 countries in 1947 after World War II in the wake of other new multilateral institutions dedicated to international economic cooperation – such as the World Bank and the International Monetary Fund. A comparable international institution for trade, named the International Trade Organization never started as the U.S. and other signatories did not ratify the establishment treaty, and so GATT slowly became a de facto international organization.

Seven rounds of negotiations occurred under GATT. The first real GATT trade rounds concentrated on further reducing tariffs. Then the Kennedy Round in the mid-sixties brought about a GATT anti-dumping Agreement and a section on development. The Tokyo Round during the seventies represented the first major attempt to tackle trade barriers that do not take the form of tariffs, and to improve the system, adopting a series of agreements on non-tariff barriers, which in some cases interpreted existing GATT rules, and in others broke entirely new ground. Because not all GATT members accepted these plurilateral agreements, they were often informally called “codes”. Several of these codes were amended in the Uruguay Round and turned into multilateral commitments accepted by all WTO members. Only four remained plurilateral, but in 1997 WTO members agreed to terminate the bovine meat and dairy agreements, leaving only two. Despite attempts in the mid-1950s and 1960s to establish some form of institutional mechanism for international trade, the GATT continued to operate for almost half a century as a semi-institutionalized multilateral treaty regime on a provisional basis.

20 December 1995

American Airlines Flight 965 crashes north of Cali, Colombia killing 159.

American Airlines Flight 965 was a regularly scheduled flight from Miami International Airport in Miami, Florida, to Alfonso Bonilla Aragón International Airport in Cali, Colombia. On December 20, 1995, the Boeing 757-200 flying this route crashed into a mountain in Buga, Colombia, killing 151 out of the 155 passengers and all eight crew members. Flight 965 was the deadliest air disaster involving a U.S. carrier since the bombing of Pan Am Flight 103 in 1988. Five passengers, all seated within two rows of each other, survived the initial impact, but one died two days later of his injuries. In addition to the four human survivors, a dog who had been in a carrier in the cargo hold at the time of the crash, also survived the incident.

The Colombian Special Administrative Unit of Civil Aeronautics investigated the accident and determined it was caused by navigational errors by the flight crew.

At that time, Flight 965 mainly carried people returning to Colombia for the Christmas holiday, vacationers and businesspeople. A winter storm in the northeast United States caused the airline to delay the departure of the airliner for thirty minutes to allow for connecting passengers to board the flight, so Flight 965 pushed back from Gate D33 in Miami at 5:14 pm, and then taxied to runway 27R, but seasonal congestion caused the 757 to take off at 6:35 pm, 1 hour 21 minutes late.

The cockpit crew consisted of Captain Nicholas Tafuri, age 57, and First Officer Donald Williams, age 39. Both pilots were considered to be highly skilled airmen. Captain Tafuri had more than 13,000 hours of flying experience and First Officer Williams had almost 6,000 hours. The cabin crew consisted of Purser Pedro Pablo Calle and Flight Attendants Magdalena Borrero, Rosa Cabrejo, Teresa Delgado, Gilberto Restrepo, and Margaret “Maggie” Villalobos. All cabin crew personnel were born in Colombia and were veterans from Braniff International Airways who had moved to Eastern Air Lines and then to American Airlines, when the routes were transferred from one airline to the other. They had voluntarily chosen the flight, as a prerogative awarded by seniority, to spend Christmas time with their families in Bogotá.

Cali’s air traffic controllers had no functional radar to monitor the 757, as it had been blown up in 1992 by the terror group FARC. Cali’s approach uses several radio beacons to guide pilots around the mountains and canyons that surround the city. The airplane’s flight management system already had these beacons programmed in, and should have, in theory, told the pilots exactly where to turn, climb, and descend, all the way from Miami to the terminal in Cali.

Since the wind was calm, Cali’s controllers asked the pilots whether they wanted to fly a straight-in approach to runway 19 rather than coming around to runway 01. The pilots agreed, hoping to make up some time. The pilots then erroneously cleared the approach waypoints from their navigation computer. When the controller asked the pilots to check back in over Tuluá, north of Cali, it was no longer programmed into the computer, and so they had to pull out their maps to find it. In the meantime, they extended the aircraft’s speed brakes to slow it down and expedite its descent.

By the time the pilots found Tuluá’s coordinates, they had already passed over it. In response to this, they attempted to program the navigation computer for the next approach waypoint, Rozo. However, the Rozo NDB was identified as R on their charts. Colombia had duplicated the identifier for the Romeo NDB near Bogotá, and the computer’s list of stored waypoints did not include the Rozo NDB as “R”, but only under its full name “ROZO”. In cases where a country allowed duplicate identifiers, it often listed them with the largest city first. By picking the first “R” from the list, the captain caused the autopilot to start flying a course to Bogotá, resulting in the airplane turning east in a wide semicircle. By the time the error was detected, the aircraft was in a valley running roughly north-south parallel to the one they should have been in. The pilots had put the aircraft on a collision course with a 3,000-meter mountain. The air traffic controller, Nelson Rivera Ramírez, believed that some of the requests of the pilots did not make sense, but did not know enough non-aviation English to convey this.

Twelve seconds before the plane hit the mountain, named El Diluvio, the Ground Proximity Warning System activated, announcing an imminent terrain collision and sounding an alarm. Within a second of this warning the first officer disengaged the autopilot, and the captain attempted to climb clear of the mountain; however, neither pilot had remembered to disengage the previously deployed speed brakes, which reduced the rate of climb. At 9:41:28 pm Eastern Standard Time it struck trees at about 8,900 feet MSL on the east side of the mountain. The crash was six miles south of Tuluá VOR and 28 miles north of the approach end of runway 19 at Alfonso Bonilla Aragon International Airport. During the investigations, it was found that neither the Boeing fixed-base simulator nor the flight management system simulator could be backdriven with the data obtained directly from the accident airplane’s flight data recorder. Because the 757 flight simulators could not be backdriven during the tests, it could not be determined with precision whether the airplane would have missed the mountain/tree tops if the speedbrakes had been retracted during the escape attempt. However, the final report stated that if the flightcrew had retracted the speedbrakes one second after initiating the escape maneuver, the airplane could have been climbing through a position that was 150 feet above the initial impact point. Because the airplane would have continued to climb and had the potential to increase its rate of climb, it might well have cleared the trees at the top of the mountain.

Scavengers took engine thrust reversers, cockpit avionics, and other components from the crashed 757, using Colombian military and private helicopters to go to and from the crash site. Many of the stolen components re-appeared as unapproved aircraft parts on the black market in Greater Miami parts brokers. In response, the airline published a 14-page list stating all of the parts missing from the crashed aircraft. The list included the serial numbers of all of the parts.

In 1997 U.S. District Judge Stanley Marcus ruled that the pilots had committed “willful misconduct”; the ruling applied to American Airlines, which represented the dead pilots. The judge’s ruling was subsequently reversed in June 1999 by the U.S. Court of Appeals in Atlanta, which also overturned the jury verdict and declared that the judge in the case was wrong in issuing a finding of fault with the pilots, a role which should have been reserved for the jury only.

American Airlines settled numerous lawsuits brought against it by the families of the victims of the accident. American Airlines filed a “third-party complaint” lawsuit for contribution against Jeppesen and Honeywell, which made the navigation computer database and failed to include the coordinates of Rozo under the identifier “R”; the case went to trial in United States District Court for the Southern District of Florida in Miami. At the trial, American Airlines admitted that it bore some legal responsibility for the accident. Honeywell and Jeppesen each contended that they had no legal responsibility for the accident. In June 2000, the jury found that Jeppesen was 30 percent at fault for the crash, Honeywell was 10 percent at fault, and American Airlines was 60 percent at fault.

An enhanced ground proximity warning system was introduced in 1996, which could have prevented the accident.

Since 2002, all planes with more than six passengers are required to have an advanced terrain awareness warning system.

As of November 2017, American Airlines still operates the Miami-Cali route, but as American Airlines Flight 921 and using a Boeing 737-800.

22 November 1995

Toy Story is released as the first feature-length film created completely using computer-generated imagery.

Toy Story was released in theaters on November 22, 1995, and was the highest-grossing film on its opening weekend, eventually earning over $373 million at the worldwide box office. It was positively reviewed by critics and audiences, who praised the animation’s technical innovation, the wit and thematic sophistication of the screenplay, and the performances of Hanks and Allen; it is considered by many to be one of the best animated films ever made. The film received three Academy Award nominations, including Best Original Screenplay, Best Original Score, and Best Original Song for “You’ve Got a Friend in Me”, as well as winning a Special Achievement Academy Award. In 2005, it was inducted into the National Film Registry as being “culturally, historically, or aesthetically significant” in its first year of eligibility. In addition to home media and theatrical re-releases, Toy Story-inspired material includes toys, video games, theme park attractions, spin-offs, merchandise, and two sequels — Toy Story 2 and Toy Story 3 — both of which also garnered massive commercial success and critical acclaim, with a fourth film titled Toy Story 4 scheduled for release in 2019.

The movie depicts a world where toys are living things but pretend to be lifeless when humans are present. A group of toys, owned by six-year-old Andy Davis, are caught off-guard when Andy’s birthday party is moved up a week, as his family is preparing to move the following week. A pull-string cowboy doll named Sheriff Woody – the toys’ leader and Andy’s favorite toy – organizes a scouting mission, with the help of Bo Peep the shepherdess, Mr. Potato Head, Rex the Dinosaur, Hamm the Piggy Bank and Slinky Dog. Green Army Men, led by Sarge, spy on the party, and report the results to the others via baby monitors. The toys are relieved when the party appears to end with none of them being replaced by new toys, but then Andy receives a gift – a Buzz Lightyear action figure, who thinks he is a real space ranger.

Buzz impresses the other toys with his various features, and Andy begins to favor him, making Woody feel abandoned. As Andy prepares for a family outing at Pizza Planet, his mother allows him to bring one toy. Fearing Andy will choose Buzz, Woody attempts to trap Buzz behind a desk, but ends up accidentally knocking him out of a window. The other toys rebel against Woody, believing he did harm to Buzz out of jealousy. Before they can exact revenge, Andy takes Woody and leaves for Pizza Planet. When the family stops for gas, Woody finds that Buzz has hitched a ride on the car as well. They have a fight, only to find the family has left without them. They manage to make their way to the restaurant by stowing away on a pizza delivery truck. Buzz, still thinking he is a real space ranger, despite Woody’s attempts to convince him otherwise, gets them stuck in a crane game, where they are salvaged by Andy’s mischievous neighbor, Sid Phillips.

Woody attempts to escape from Sid’s house, but Buzz, finally realizing he is a toy after watching a Buzz Lightyear TV ad, sinks into despondency. Sid plans to launch Buzz on a fireworks rocket, but his plans are delayed by a thunderstorm. Woody tells Buzz about the joy he can bring to Andy as a toy, restoring his confidence. The next day, Woody and Sid’s mutant creature toys rescue Buzz just as Sid is about to launch the rocket and scare Sid into no longer abusing toys, and he runs into his house screaming in horror. Woody and Buzz leave just as Andy and his family drive away toward their new home.

The duo tries to make it to the moving truck, but Sid’s dog, Scud, sees them and gives chase. Buzz gets left behind while saving Woody from Scud, and Woody tries rescuing him with Andy’s radio-controlled car. Thinking that Woody is trying to eliminate RC as well, the other toys attack and toss him off the truck. Having evaded Scud, Buzz and RC retrieve Woody and continue to chase the truck. Upon seeing Woody and Buzz together on RC, the other toys realize their mistake and try to help them get back aboard, but RC’s batteries become depleted, stranding them. Woody ignites the rocket on Buzz’s back and manages to throw RC into the truck before they soar into the air. Buzz opens his wings to free himself from the rocket before it explodes, gliding with Woody to land safely into a box in the car, right next to Andy.

On Christmas Day, at their new house, Woody and Buzz stage another reconnaissance mission to prepare for the new toy arrivals. One of the toys is Mrs. Potato Head, much to Mr. Potato Head’s delight. As Woody jokingly asks what might be worse than Buzz, they discover Andy’s new gift is a puppy, and the two share a worried smile.