In the news this month... and finally
Jupiter on July 24th by Anthony Wesley, Murrumbateman NSW Australia CREDIT: Anthony Wesley
Almost exactly 15 years after astronomers around the world watched as fragments of the comet Shoemaker-Levi 9 hit Jupiter, leaving black scars on the planet's cloudy surface, an amateur astronomer caught images of another impact on the gas giant. First imaged on July 19th by Anthony Wesley in New South Wales, Australia, news of the impact rapidly spread around the world. Within hours, several observers had confirmed the new black blemish on Jupiter's surface, and within days it had been imaged by the Keck telescope and NASA's Infrared Telescope Facility in Hawaii. The infra red observations showed that the scar was warm, indicating as upwelling of material in the planet's atmosphere, probably caused by an impact. Even the recently upgraded Hubble Space Telescope was used to image the event, despite commissioning of the new instruments not being complete. The Hubble image was the first science observation carried out with the newly installed Wide Field Camera 3 and shows the instrument is performing well. The most recent images of the impact site show that the black spot is evolving and now contains two nuclei, probably due to the high winds and complex dynamics in Jupiter's dense atmosphere.
By coincidence, another amateur astronomer, Frank Melillo of New York in the USA, spotted a new feature in the atmosphere of Venus on the same day. The Venus Express spacecraft in orbit around the planet confirmed that the spot had first appeared four days earlier. Observations in the ultra violet suggest that this feature was not caused by a meteorite impact and various suggestions have been put forward, such as a volcanic eruption, or a concentration of charged particles from the Sun, but as yet it is not known exactly what caused it.