June 15th: Displaying Saturn


365daysDate: June 15, 2009

Title: Displaying Saturn


Podcaster: Marek Kukula of the Royal Observatory, Greenwich

Organization: The Royal Observatory, Greenwich

Description: Starting in June 2009 the Royal Observatory Greenwich is staging an exhibition of images taken by NASA’s Cassini spacecraft, currently in orbit around Saturn. In this podcast staff from the Observatory will talk about the process of selecting and displaying astronomical images in a museum setting, ensuring that both beauty and science get equal billing.

Bio: The Royal Observatory, Greenwich was founded by King Charles II in 1675. Now part of the UK’s National Maritime Museum the observatory site is open daily to the public with exhibitions on the history of astronomy and contemporary space science, as well as regular shows in the Peter Harrison Planetarium.

Today’s sponsor: This episode of 365 Days of Astronomy is sponsored by AAVSO.


Marek Kukula: Hi I’m Dr Marek Kukula, the Public Astronomer at the Royal Observatory Greenwich and the subject of this podcast is a new exhibition opening in June at the Observatory featuring images from the Cassini-Huygens mission to Saturn. Greenwich is no longer an active research observatory but as a museum and science centre our mission is still to promote and explain modern, cutting edge astronomy to the public.

The Cassini spacecraft arrived at Saturn in 2004 and it’s been sending back a constant stream of images and data ever since. It also dropped the Huygens lander onto Saturn’s giant fog-shrouded moon Titan, showing us details of the surface for the first time. I think it’s fair to say that between them the Cassini & Huygens craft have revolutionised our view of Saturn, its rings and its moons but, as well as being a scientific treasure trove, many of the images they’ve sent back are also visually stunning. So it was a natural choice for us as the subject of an exhibition.

Greenwich also has a special Saturn connection because here on site we have a surviving fragment of William Herschel’s giant 40-foot telescope. Herschel was one of the greatest astronomers of the 18th and early 19th centuries and it was possibly through this telescope that he discovered two of Saturn’s moons, Mimas and Enceladus. With our exhibition we’re able to bring that story bang up to date because Enceladus has been the source of some of Cassini’s most exciting discoveries, and we have some amazing images showing jets of water spraying from cracks in the moon’s surface.

Dr. Claire Bretherton is one of the astronomers here at the Observatory and she’s putting together a planetarium show about Saturn to complement the exhibition. Claire, perhaps you could start by telling us a little about the planetarium and what it can do?

Claire Bretherton: Well here at the Royal Observatory we have London’s only planetarium and because we have a state-of-the-art digital system we can do some fantastic things like actually fly you from Earth to Saturn just like Cassini. And we have digital models of the solar system within the planetarium software so we can also take you on tour of the rings and moons once you’re there.

MK: But the system also allows you to include real images and movies from the spacecraft, right?

CB: Yes, we can use real images. Once we’ve taken you to Saturn via computer graphics we can then put the real data sent back by Cassini and Huygens up onto the dome. Having those real images is fantastic because we’re also going to have real scientists there to talk the public through them.

MK: So there’s going to be live narration by scientists who are actually involved in the mission?

CB: Yes the shows will be introduced by our own astronomers who’ll then hand over to a specialist who can go into a lot more detail about the images and the data that we’re seeing.

MK: That’s great because one of the things that we like to do here in Greenwich is to get the public to interact with scientists so this sounds like a really great way of doing that.

CB: Absolutely! And every show that we do here at the Royal Observatory is introduced by a real astronomer so there’s always somebody to ask questions to at the end of a planetarium show.

MK: Now Claire here’s a question for you: do you have a favourite image in the exhibition?

CB: There are so many fantastic images but my favourite is a natural-colour image of a section of Saturn’s rings. You can easily see the broad rings and the gaps in between them but each broad ring is actually made up of thousands of ringlets so the closer you look the more you see.

MK: Now it’s probably worth pointing out that the exhibition has been put together working very closely with scientists from the Cassini & Huygens missions so we’ve actually got them to choose some of their own favourite images which are in the exhibition as well.

CB: Marek, your focus is obviously very much on explaining astronomy to the public. The images in the exhibition all contain huge amounts of scientific information but how do you choose what to put in and what to leave out?

MK: Well you’re right, it’s a huge problem because as a scientist you naturally want to include everything but you have to be really disciplined and whittle it down to just a few images and a few key messages.

CB: What would you say are the key messages we’re trying to get across?

MK: Well I think we’ve narrowed it down to four areas and the first of those is Saturn itself and its atmosphere. From a distance it looks like a placid sphere of gas but what Cassini has shown us is that in close up it’s seething with really violent storms and lightning and things like that, so we really wanted to get that across. A second theme is a really obvious one – the rings of Saturn. Again, Cassini has sent back beautiful images showing these amazing structures and the incredible, intricate detail that’s in there. Another theme is the many moons of Saturn and I think one of the really striking messages that has come back from Cassini is that all of these moons are incredibly diverse and different from each other. We’ve tried to give a sample of that diversity by showing just a few of the moons and some of the amazing features that have been discovered there. And then finally – we couldn’t miss it out – it’s Ttan, the planet-sized moon of Saturn which is shrouded in this thick nitrogen atmosphere and an orange haze of bizarre chemicals. What Cassini and the Huygens probe have done is show us for the first time what lies beneath this atmosphere and shown us a first glimpse of the surface – so that’s really exciting.

CB: And do you have a favourite image in the exhibition?

MK: I do. It’s very, very tough to pick just one image and actually the one that I’ve selected is not really an image in a traditional sense. It’s a radar scan of the north polar region of Titan. Cassini’s radar is able to see down through the thick haze in the atmosphere and what it reveals is a landscape of very rugged hills cut through by these sinuous, winding river channels that flow into an enormous sea of liquid methane and ethane. It’s just an amazing image because it looks for all the world like the Greek coastline, the Aegean islands. It’s amazing to think that this landscape is up there, billions of miles away.

The exhibition, Visions of Saturn, launches on June 22nd at the Royal Observatory Greenwich and it runs until the end of August. It’s open from 10am til 5pm every day and admission is absolutely free. There’s also an accompanying programme of evening talks from scientists involved in the mission, a weekend of Saturn-themed activities for families and the new planetarium show which Claire was telling us about. Details of all of this are on the Royal Observatory Greenwich website.

End of podcast:

365 Days of Astronomy
The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow…goodbye.

About Marek Kukula

Dr Marek Kukula is the Public Astronomer at the Royal Observatory Greenwich. The Royal Observatory, Greenwich was founded by King Charles II in 1675. Now part of the UK’s National Maritime Museum the observatory site is open daily to the public with exhibitions on the history of astronomy and contemporary space science, as well as regular shows in the Peter Harrison Planetarium.

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