It's tough to be the biggest planet in the solar system, and this fall Jupiter is taking a beating.
On Oct. 15, skywatchers in Japan observed a flash in the atmosphere of the planet's northern hemisphere likely caused by an asteroid slamming into Jupiter, just over a month after a skywatcher in Brazil made a similar observation (opens in new tab).
"The flash felt like it was shining for a very long time to me," Twitter user @yotsuyubi21 (opens in new tab), who photographed the flash with a Celestron C6 telescope, told Space.com.
10月15日22:24(JST)に発生した、木星表面へ小天体が衝突した瞬間の閃光について、PONCOTS観測システムを用いて可視500-750nm及び889nmメタンバンドによる同時観測に史上初めて成功しました。２色同時に得られた閃光の画像をここに初公開いたします。 pic.twitter.com/Hs2wJp0s5FOctober 17, 2021
They confirmed the observation with a team led by Ko Arimatsu, an astronomer at Japan's Kyoto University who takes part in the Organized Autotelescopes for Serendipitous Event Survey (OASES) project.
According to a tweet (opens in new tab) posted by the project, that observation included two different types of light, visible and infrared, giving Jupiter an eerie pink glow.(opens in new tab)
Jupiter regularly experiences such impacts because of the powerful gravitational tug associated with its mass: Smaller objects, like the asteroids that litter the solar system, can easily end up pulled into the planet's thick, turbulent atmosphere.
Some research (opens in new tab) suggests that objects at least 150 feet (45 meters) across hit Jupiter every few months on average, although observational constraints mean that even the most thorough monitoring program might be able to catch just one impact or so per year.
According to Sky & Telescope (opens in new tab), the Oct. 15 flash hit the planet's North Tropical Zone, near the southern edge of the North Temperate Belt.
Observers aren't yet sure whether the impact left a debris field that scientists can monitor; the September flash did not, and several factors including the object's size and the impact's location factor into observability.