Context. Regular observations of Jupiter by a large number of amateur astronomers have resulted in the serendipitous discovery of short bright flashes in its atmosphere, which have been proposed as being caused by impacts of small objects. Three flashes were detected: one on June 3, 2010, one on August 20, 2010, and one on September 10, 2012. Aims. We show that the flashes are caused by impacting objects that we characterize in terms of their size, and we study the flux of small impacts on Jupiter. Methods. We measured the light curves of these atmospheric airbursts to extract their luminous energy and computed the masses and sizes of the objects. We ran simulations of impacts and compared them with the light curves. We analyzed the statistical significance of these events in the large pool of Jupiter observations. Results. All three objects are in the 5−20 m size category depending on their density, and they released energy comparable to the recent Chelyabinsk airburst. Model simulations approximately agree with the interpretation of the limited observations. Biases in observations of Jupiter suggest a rate of 12−60 similar impacts per year and we provide software tools for amateurs to examine the faint signature of impacts in their data to increase the number of detected collisions. Conclusions. The impact rate agrees with dynamical models of comets. More massive objects (a few 100 m) should impact with Jupiter every few years leaving atmospheric dark debris features that could be detectable about once per decade.

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On 7th August 2019, an impact flash lasting ∼ 1s was observed on Jupiter. The video of this event was analysed to obtain the lightcurve and determine the energy release and initial mass. We find that the impactor released a total energy of 96 − 151 kilotons of TNT, corresponding to an initial mass between 190 − 260 metric tonnes with a diameter between 4 − 10m. We developed a fragmentation model to simulate the atmospheric breakup of the object and reproduce the lightcurve. We model three different materials: cometary, stony and metallic at speeds of 60, 65 and 70 km/s to determine the material makeup of the impacting object. The slower cases are best fit by a strong, metallic object while the faster cases require a weaker material.

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