The impact point, what was described in the magazine Science as a “giant black smudge,” was found near the south pole of the planet Jupiter. [Science: “Jupiter's Been Hit!”]
The Guardian.co.uk article “Amateur astronomer spots Earth-size scar on Jupiter” describes it as “… a hole the size of the Earth in the planet's atmosphere.”
Two NASA astronomers took images of Jupiter, on Monday, July 20, 2009, with the NASA Infrared Telescope in Hawaii.
The day before, these two astronomers—Leigh Fletcher, a JPL post-doctoral student, and JPL astronomer Glenn Orton—were contacted by Australian amateur astronomer Anthony Wesley about the blemish on Jupiter.
In the same July 20, 2009 Science article, Fletcher states, "I never expected I'd get to see something like this.”
The event is only the second time that an impact of Jupiter has been observed by astronomers. The first time was in 1994 when pieces of Comet Shoemaker-Levy 9 (or, SL9, formally called D/1993 F2) hit Jupiter.
Australian computer programmer Anthony Wesley, the amateur astronomer who was the first to observe the impact site on Jupiter (on July 19, 2009), was using a 37-inch telescope in Murrumbaterman, Australia, which is located outside of Canberra.
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At about 11:30 p.m. local time, Wesley began to observe a strange spot on Jupiter that was several thousands of kilometers wide and off the south pole of Jupiter.
For additional comments, go to Mike Salway’s website.
And, comments made by Wesley are found at “Impact mark on Jupiter, 19th July 2009,” courtesy of Science.
Wesley contacted Fletcher and Orton (among others) who had remote access to the 3-meter NASA Infrared Telescope, which is located on the summit of Mauna Kea, Hawaii, from this location at JPL.
The pair observed the same impact point as Wesley, verifying his result. The impact site is said to be located at about 216 degrees longitude in System 2.
In fact, Dr. Orton had observed the first known impact of Jupiter by an object in 1994, when Comet Shoemaker-Levy 9 impacted the planet.
Science reports this story at: “Shoemaker-Levy Dazzles, Bewilders Kerr" (Science 29 July 1994: 601-602 DOI: 10.1126/science.265.5172.601; subscription required).
The Guardian story also states that the discovery is “... is a remarkable twist of fate, the discovery was made on the 40th anniversary of the Apollo 11 moon landing and the 15th anniversary of another large comet strike on Jupiter."
For additional information, check out Space.com’s article “Jupiter Apparently Smacked by Rogue Object, New Images Reveal.”