Yet another Jovian fireball? On May 26th, amateur astronomers recorded a rare impact flash in Jupiter's north polar region.
Jupiter just got beaned for the sixth time (that we know about)! On the evening of May 26th, between 19:24.6 and 19:26.2 Universal Time, Sauveur Pedranghelu, a French amateur from Corsica, detected an impact flash live on video in Jupiter's north polar region.
The flash was very brief, lasting only about 0.7 second, and displayed two brightness peaks. A bright dot — about the size of Europa when seen in transit — marked the site of impact at latitude 51° north and central meridian longitudes System I = 74°, System II = 159°, and System III = 292°. The position is a little east of oval BA, a.k.a. Red Spot Jr., which is located on the same face of the planet but in the southern hemisphere.
(Jupiter's rotation rate isn't the same everywhere on its globe. Its midsection spins every 9 hours 50.5 minutes, and astronomers refer to this as as the System I rotation period. That's slightly faster than the rotation rates of regions well away from the equator, which are noted as System II, or the planet's deep interior, known as System III. Here's a quick guide describing these three schemes.)
Marc Delcroix, who coordinates a worldwide group of Jupiter observers, posted an email about the the discovery to various groups. Within a day of the news, a second video by Thomas Riessler of Dettenhausen, Germany, showed an identical pinpoint flash between 19:24.6 and 19:25.0 UT — confirming Pedranghelu's observation. The estimated duration of the fireball from that video was 0.87 second.
Jupiter watchers are excitedly training telescopes and cameras on the giant planet in hopes of seeing if the meteoroid explosion left any traces similar to the dark spots in similar impacts of the past or possibly a bright spot when photographed through narrowband methane filters.
Early observations haven't turned up a trace . . . yet. On May 28th from the Philippines, planetary imager Christopher Go couldn't detect anything certain at the site, writing on his website: "There is no brightening of the impact region in methane band nor is there any noticeable impact remnant."
Perhaps larger telescopes might fish up something, but either way, it wouldn't hurt to keep the site in view. Visual observers and images worldwide are encouraged to look for an impact remnant. To determine the longitude of Jupiter's central meridian, i.e. when a particular longitude is squarely centered on the face of the planet, click here and enter the UT time and date when you'll be observing the planet. You'll be looking for times when central meridian longitude 159° (System II) is well-placed.
The first-ever confirmed impact at Jupiter occurred in July 1994, when 21 fragments of Comet Shoemaker-Levy 9 crashed into the planet in succession, creating a striking belt of sooty, dark impact spots girdling the planet. Alert to the possibility that comet and asteroid impacts might be more common than thought, amateurs began keeping a closer eye on Jove in hopes of catching sight of additional flashes. Cheap video cameras made it possible to continuously monitor the planet.
Fifteen years later, on July 19, 2009, Australian amateur Anthony Wesley hit pay dirt when he recorded a dark spot in Jupiter's clouds spawned by a colliding meteoroid. No one saw or recorded the actual flash of impact, but there was no doubt about it being the real thing. Wesley's discovery was soon followed by three additional Jovian flashes recorded by amateurs on June 3, 2010; August 20, 2010; and March 17, 2016.
Here's the Jupiter impact of June 3, 2010, discovered by Anthony Wesley and Christopher Go:
Jupiter: A Big Target
Two factors make Jupiter a great place to look for asteroid and comet collisions. First, the planet’s powerful gravity can draw in debris that happens to stray too close. Second, that same gravity accelerates even small objects to such high speeds that they deliver maximum bang for the buck.
Here's the Jupiter impact on March 17, 2016, as recorded by John McKeon:
According to Bad Astronomy blogger Phil Plait: “On average (and ignoring orbital velocity), an object will hit Jupiter with roughly five times the velocity it hits Earth, so the impact energy is 25 times as high.” So a fairly small object could have caused this most recent flash.
Who knows what you might see the next clear evening when Jupiter, standing high and bright, extends an invitation?