Amateur astronomer spots scar

Anthony Wesley, 44, a computer programmer who lives in a small town near Canberra, discovered a large scar on Jupiter when he was photographing the giant gaseous planet. He tipped off Nasa about his discovery, and images taken by the US space agency’s infrared telescope in Hawaii show a scar in the atmosphere near the south pole of the planet.

In a remarkable twist of fate, the discovery was made on the 40th anniversary of the Apollo 11 moon landing and the 15th anniversary of another large comet strike on Jupiter.

Wesley, who spends about 20 hours a week on his passion of watching and photographing Jupiter, spotted the strike using the telescope at the bottom of his garden in Murrumbatema. But he almost missed making the discovery because he was watching the Open golf championship and the second Ashes test match.

He recorded the moment in his observation log: “I noticed a dark spot rotating into view in Jupiter’s south polar region and started to get curious,” he said. “My next thought was that it must be either a dark moon ... or a moon shadow, but it was in the wrong place and the wrong size.”

More evidence

Wesley emailed scientists at Nasa’s jet propulsion laboratory in Pasadena, California. Using Nasa’s infrared telescope facility at the summit of Mauna Kea, Hawaii, they gathered evidence indicating an impact.

“We were extremely lucky to be seeing Jupiter at exactly the right time, the right hour, the right side of Jupiter to witness the event. We couldn’t have planned it better,” said Glenn Orton, a scientist at Pasadena.

“It could be the impact of a comet, but we don’t know for sure yet,” he said. “It’s been a whirlwind of a day, and this on the anniversary of the Shoemaker-Levy 9 and Apollo anniversaries is amazing.”

Wesley has been an ardent star-gazer since the age of 10 when he was given a small telescope. But over the past five years he has been in Jupiter’s thrall. “It’s one of my passions. It’s such a dynamic planet, it’s changing all the time. To take a photograph of this type, really it’s a dream come true for me.”

Leigh Fletcher, another Nasa scientist, said: “The impact scar we’re seeing is about the same size as one of Jupiter’s big storms ... That, I believe, is about the size of the Earth.”