Jupiter Whacked Again? Japanese Astronomers Record Possible Impact

By: Bob King October 18, 2021 2

A group of Japanese astronomers just discovered a potential new impact at the planet Jupiter.

Jupiter impact flash Oct. 15, 2021 — Japanese amateur astronomer yotsuyubi21 captured a possible impact flash in Jupiter's North Tropical Zone (NTrZ) at 13:24 UT on October 15th using a Celestron C6. See update note at the end of this post.
*yotsuyubi21*

Get your scorecards out — Jupiter just took another interplanetary hit. If it's confirmed it would be the 11th observed comet or asteroid strike at the gas giant since the pieces of Comet Shoemaker-Levy 9 slammed into Jupiter in 1994.

A little more than a month after five amateurs independently recorded a similar flash, a team of astronomers, led by Ko Arimatsu of Kyoto University, captured this most recent flare in Jupiter's cloud tops (IR/visible image below) at 13:24 UT on Friday, October 15th.

The potential impact flash appears around the 12-second mark in this video of Jupiter made on Friday, October 15th.
yotsuyubi21

Arimatsu and the group used a surveillance system called PONCOTS as part of the Organized Autotelescopes for Serendipitous Event Survey (OASES) project to make their discovery. The event occurred in Jupiter's North Tropical Zone near the southern edge of the North Temperate Belt at latitude +20° North and longitude 201° (System II). From the video, the burst lasted about 4 seconds. It quickly rises into visibility, maintains a steady light for about 2 seconds and then swiftly disappears.

Jupiter's belts and zones — Jupiter displays alternating dark belts and bright zones that help in identifying any potential impact scars in the wake of the most recent flash. Zones are colder and mark upwelling ammonia ice clouds; belts are warmer regions marked by descending gases.
*Sky & Telescope illustration*

According to the Europlanet Society, on average 6½ objects 10 meters across and larger (that is, big enough for amateurs to record) hit Jupiter each year. Aided by transient-alert software like DeTeCt, we've seen a steady uptick in the number of impacts in recent years, proving that the more we look, the more we see. The most recent impact, in September, didn't produce a visible impact scar. This one may not either. But both events make us keenly aware of the potential hazards that still lurk in our solar system.

Jupiter impact flash in false color — This is a false-color view of the impact, combining visible and infrared exposures. Arimatsu's team used a 28-cm Schmidt-Cassegrain telescope (Celestron C11) and an original, Python-based pipeline developed for impact flash detections
*Ko Arimatsu / Kyoto University*

Detailed image of Jupiter impact flash — After hearing about the discovery from Japan, Victor PS Ang of Singapore quickly checked his own videos of Jupiter with DeTeCt impact detection software. "When I saw a little light flashing on the Jupiter surface on my computer screen, this really brightened up my day! I immediately shared the joy with my wife. "
*Victor PS Ang*

Jupiter flash sequence — Victor PS Ang combined images from video he made of the impact flash to create this detailed sequence. "I estimated the impact flashes lasted about 7 to 8 seconds based on this time sequence image," said Ang. He used a C14 Edge HD Telescope with a Tele Vue 2.5 x Barlow and ASI290MC CMOS color camera for his captures.
*Victor PS Ang*

Jupiter impact video — Wait for it. This animation shows the October 15th impact on Jupiter.
*Victor SP Ang*

Amateurs who photographed and took video of the Jupiter around the time of the potential impact are urged to contact either Marc Delcroix or Ricardo Hueso to provide confirmation of the event. Let us here at Sky & Telescope know, too! Just leave a comment, and I'll make sure to contact you.

** Update October 19, 2021 — Good news! The flash was confirmed by a second observer, Japanese amateur astronomer yotsuyubi21, who prefers to go by their Twitter handle.

** Update October 28, 2021 — Victor PS of Ang of Singapore also confirmed the impact flash (see photos above).

Editorial note: This article has been updated to attribute the infrared/visible observation to Ko Arimatsu (Kyoto University) and the visible-light video to Twitter user yotsuyubi21.