Anthony Wesley: Imaging Jupiter & Saturn
This was Anthony Wesley's first visit to the Macarthur Astronomy Forum and welcoming an amateur astronomer (like us) to address us was refreshing. Anthony is a member of the Canberra Astronomical Society and observes regularly from his home observatory at Murrumbateman (between Canberra and Yass).
Unlike most of us, Anthony is a specialist astronomer. He concentrates on lunar and planetary imaging - Jupiter and Saturn in particular. He does it so well that he is world renowned for his Jupiter images and as Chris Malikoff said in his introduction, Anthony is one of the two best Jupiter imagers in the world.
Anthony Wesley begins his talk. Chris won't sit down!
Anthony's presentation to our Forum was a sumptuous viewing of his best personal images of Saturn and Jupiter, taken over the last four years. His glorious Jupiter images showed us how it's surface features changed over time, with spots and storms, coming and going, the South Equatorial Belt disappearing for twelve months and being replaced by a pale green belt (green is a rare colour on Jupiter) and then reappearing again last year.
He showed us images he took of a rare transit of Callisto and he showed us red spots, white spots and orange spots – many of the features that most of us might gloss over unless they are pointed out to us.
Most importantly Anthony showed us the black spot which he discovered on 19th July 2009, following an object impacting with Jupiter on the far side. This event is now generally known as the Wesley Impact. Apparently the Hubble Space Telescope was being serviced at the time but was then rushed back into use a month early to observe the impact site first discovered by Anthony. Wikipedia states that infra-red observation by Keck and the NASA Infra-red Telescope Facility at Mauna Kea showed a bright spot where the impact took place, indicating that the impact warmed a 190 million square km area of the lower atmosphere!
Preliminary image by Anthony Wesley showing a black impact mark in Jupiter's South Polar Region.
Anthony doesn't strike me as being an easily excitable type of person but he described how he contained his intense excitement upon realising the importance of the discovery he had just made. After informing NASA and reporting the discovery to other astronomers worldwide, he contemplated waking his wife to tell her about it. Wisely, he waited until breakfast time, when she said something along the lines of “That's nice, dear” and rushed off to work. Later in the day she (excitedly) called Anthony at home and exclaimed that his discovery was the main news item of the day. “I know,” said Anthony, “The TV crews are all in the front garden!”
We were treated to numerous beautiful pictures of Saturn and some wonderful images of the recent white storm that encircled Saturn. His images showed Saturn with it's exquisite rings almost edge on in 2008 and progressing to the rings much wider as they are now in 2012. He told us that the rings are thirty per cent brighter at opposition but fade as the equinox approaches.
Apparently, the Cassini project does not routinely image Saturn for surface changes, it concentrates more on the rings and satellites. So it is not uncommon for Anthony to find a new storm feature before NASA does. Anthony e-mailed the Cassini team more than once to ask them if they had taken any images of particular new storms on Saturn and got the message back: “What storm?.” Imagine that - NASA has this astonishing on-the-spot Cassini spacecraft imaging the Saturn system non-stop, yet they are unaware of major storms on the planet's surface until a NSW amateur astronomer lets them in on it!
This was a great presentation of some truly fabulous planetary images, personally presented by one of the most highly respected amateur planetary imaging specialists in the world. One of the advantages of specialising in planetary observing is that you don't need to worry about light pollution – just clouds!
Anthony's final advice to us was to look forward to 2017, when there will be a spectacular trinity of Mars, Jupiter and Saturn all coming to opposition at about the same time. I look forward to that!
This month: prepare to be absolutely astonished by the deep sky images taken and processed by Humayun Qureshi!
September: another visit by the amazing Professor Geraint Lewis!
This article was written for publication in the August Edition of "Prime Focus" magazine - the journal of Macarthur Astronomical Society.
Image of Jupiter is copyright Anthony Wesley.