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Sunday, May 22, 2016

JUPITER PLANET - Jupiter Fireballs: Big Impacts Occur 6 to 7 Times Per Year

Jupiter Fireballs: Big Impacts Occur 6 to 7 Times Per Year:

The Jupiter fireball of March 17, 2016, captured by Gerrit Kernbauer and John McKeon.

Credit: G. Kernbauer, J. McKeon, S. Voltmer

Jupiter doesn't get whacked by asteroids and comets quite as often as scientists had thought.

Objects big enough to generate a fireball visible from Earth — such as the spectacular one that occurred on March 17 — slam into Jupiter about 6.5 times per year, according to a new study based on the pooled observations of amateur astronomers around the world.

"In three years since our program started, amateur contributors from Europe, the U.S. and Australia have analyzed the equivalent of more than 56 days of videos — around 53,000 videos — without discovering an impact," Marc Delcroix, who coordinates a group of about 60 skywatchers worldwide, said in a statement. [Jupiter Collision! Impact Captured by Amateur Astronomer (Video)]

"This is a result in itself and, together with the reports of amateur astronomer John McKeon, has helped us come up with our preliminary estimate, which slightly reduces previous estimates of the flux of impacting objects [at] Jupiter," Delcroix added.

McKeon captured the March 17 Jupiter fireball on video. (Another amateur astronomer, Gerrit Kernbauer, spotted the impact first; McKeon went through his observations from that night after learning of Kernbauer's find.)

Researchers think that the March 17 event was caused by an object 33 to 66 feet (10 to 20 meters) wide. Skywatchers have observed three other such Jupiter strikes since June 2010; all of them likely involved impactors in the same general size range, scientists have said.

But bigger objects hammer the gas giant fairly frequently as well. A 1,650-foot-wide (500 m) asteroid barreled into Jupiter in 2009, for example, and the big chunks of broken-apart Comet Shoemaker-Levy 9 pummeled the huge planet in July 1994, leaving dark scars that were visible in Jupiter's cloud tops for months.

Jupiter is much bigger and more massive than Earth, so the giant planet gets hit by cosmic objects thousands of times more often than our planet does. (Asteroids and comets are drawn in more frequently by Jupiter's powerful gravity.)

Nailing down Jupiter's precise impact rate is of interest to astronomers and planetary scientists as well as skywatchers.

"Unfortunately, we are still dealing with the statistics of a very few number of impacts detected, but plans to improve our detection methods and perform systematic searches will help us to detect more of these objects," Ricardo Hueso Alonso, of the University of the Basque Country in Spain, said in the same statement. "That will allow us to know more about the current architecture of the outer solar system and the role of Jupiter in protecting the Earth from comparable impacts."

The study team presented its results at a workshop on Jupiter for professional and amateur astronomers at the Observatoire de la Côte d’Azur in Nice, France. The workshop was organized by the Europlanet 2020 Research Infrastructure, a project designed to support planetary-science activities throughout Europe.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

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The National Aeronautics and Space Administration (NASA) is the United States government agency responsible for the civilian space program as well as aeronautics and aerospace research. President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA's predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

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The Oxford English Dictionary defines a UFO as "An unidentified flying object; a 'flying saucer'." The first published book to use the word was authored by Donald E. Keyhoe. The acronym "UFO" was coined by Captain Edward J. Ruppelt, who headed Project Blue Book, then the USAF's official investigation of UFOs. He wrote, "Obviously the term 'flying saucer' is misleading when applied to objects of every conceivable shape and performance. For this reason the military prefers the more general, if less colorful, name: unidentified flying objects. UFO (pronounced Yoo-foe) for short." Other phrases that were used officially and that predate the UFO acronym include "flying flapjack", "flying disc", "unexplained flying discs", "unidentifiable object", and "flying saucer". The phrase "flying saucer" had gained widespread attention after the summer of 1947. On June 24, a civilian pilot named Kenneth Arnold reported seeing nine objects flying in formation near Mount Rainier. Arnold timed the sighting and estimated the speed of discs to be over 1,200 mph (1,931 km/h). At the time, he described the objects' shape as being somewhat disc-like or saucer-like, leading to newspaper accounts of "flying saucers" and "flying discs". In popular usage the term UFO came to be used to refer to claims of alien spacecraft. and because of the public and media ridicule associated with the topic, some investigators prefer to use such terms as unidentified aerial phenomenon (or UAP) or anomalous phenomena, as in the title of the National Aviation Reporting Center on Anomalous Phenomena (NARCAP).

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UFO - Unidentified Flying Object An unidentified flying object, or UFO, in its most general definition, is any apparent anomaly in the sky that is not identifiable as a known object or phenomenon. Culturally, UFOs are associated with claims of visitation by extraterrestrial life or government-related conspiracy theories, and have become popular subjects in fiction. While UFOs are often later identified, sometimes identification may not be possible owing to the usually low quality of evidence related to UFO sightings (generally anecdotal evidence and eyewitness accounts). Stories of fantastical celestial apparitions have been told since antiquity, but the term "UFO" (or "UFOB") was officially created in 1953 by the United States Air Force (USAF) to serve as a catch-all for all such reports. In its initial definition, the USAF stated that a "UFOB" was "any airborne object which by performance, aerodynamic characteristics, or unusual features, does not conform to any presently known aircraft or missile type, or which cannot be positively identified as a familiar object." Accordingly, the term was initially restricted to that fraction of cases which remained unidentified after investigation, as the USAF was interested in potential national security reasons and/or "technical aspects" (see Air Force Regulation 200-2). During the late 1940s and through the 1950s, UFOs were often referred to popularly as "flying saucers" or "flying discs". The term UFO became more widespread during the 1950s, at first in technical literature, but later in popular use. UFOs garnered considerable interest during the Cold War, an era associated with a heightened concern for national security. Various studies have concluded that the phenomenon does not represent a threat to national security nor does it contain anything worthy of scientific pursuit (e.g., 1951 Flying Saucer Working Party, 1953 CIA Robertson Panel, USAF Project Blue Book, Condon Committee).