Category Archives: planetary science

Gemini Observatory, impacts, planetary science

Jupiter’s Southern “Bruise”

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As Seen by Gemini Observatory

The impact site of Jupiter, as seen by Gemini Observatory. It looks similar to the Shoemaker-Levy 9 crash sites that appeared in 1994 after the impact of that comet with Jupiters cloud tops.
The impact site of Jupiter, as seen by Gemini Observatory. It looks similar to the Shoemaker-Levy 9 crash sites that appeared in 1994 after the impact of that comet with Jupiter's cloud tops. (Click to embiggen.)

As more observatories turn their attention to the bruise at Jupiter’s southern polar region, the images just keep getting better.  Today’s release from Gemini Observatory on Mauna Kea in Hawai’i shows a composite mid-infrared view of the impact site (the bright yellow pair of blobs at the bottom center of the image at left).

This is looking more and more like the SL-9 crash effects from 1994, a point that SL-9 veteran Heidi Hammel pointed out as she described what they see in the images. “The morphology is suggestive of an arc-like structure in the feature’s debris field,” she added.

The mid-infrared wavelength image is showing the effect of scattered material as a result of this most recent impact.  It’s likely that the impactor was a small (hundreds of meters across) comet or asteroid — not something that could have been seen from Earth even with powerful telescopes.

The Gemini images that  made up the composite were obtained with the MICHELLE spectrograph/imager. This gave a series of images at seven different mid-infrared wavelengths. Two of the images (8.7 and 9.7 microns) were combined into a color composite image by Travis Rector at the University of Alaska, Anchorage to create this final false-color image. By using the full set of Gemini images taken over a range of wavelengths from 8 to 18 microns, the team will be able to disentangle the effects of temperature, ammonia abundance, and upper atmospheric aerosol content so that they can understand just what it was that plowed into Jupiter and what chemical elements it contained. Comparing these Gemini observations with past and future images will permit the team to study the evolution of features as Jupiter’s strong winds disperse them.

This image is one of those “target of opportunity” sets that observatories plan for when they allocate time each year. Essentially, the planning committees put aside time “just in case” something happens — just like it did with this impactor at Jupiter. As scientist Imke de Pater noted, “the Gemini support staff made a heroic effort to get these data.”  The Gemini team (Tom Geballe, Chad Trujillo, Rachel Mason and Paul Hirst, aided by Glenn Orton and Leigh Fletcher (of JPL)) swung into action immediately, making the telescope available within 24 hours of the request for observing time. It’s important to get data as soon as possible during these types of events, which are “transient” — meaning that they and their effects don’t last long, and the evidence for whatever the impactor was gets dissipated pretty quickly.  For more details on this Gemini image, swing your attention to the impact’s image page at Gemini’s website.

Update:  I heard that HST has also looked at this site as a target of opportunity. Not sure exactly when in the next day or so the image(s) will be available, but whatever shows up should be spectacular!

hubble space telescope, planetary science, ring system, saturn

Quadruple Saturn By-pass

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HST Captures a View of Four of Saturn’s Many Moons

So, last entry I had you examining the details of an image of a galaxy pair some 70 or so million light-years away. Today, we’re going to look at at the details of an HST image of a scene that played out some 70 or so light-minutes away at the planet Saturn.

Four of Saturns moons transiting the planet as seen by HST. (Click to embiggen -- caution-huge image!)
Four of Saturn's moons transiting the planet as seen by HST. (Click to embiggen -- caution-huge image!)

If you click on the smaller image, you’ll get a much bigger one that shows the details of a rare transit of four of Saturn’s moons:  Titan (the large one at the top of the limb of Saturn), Mimas (below Titan and casting a shadow near the rings) and bright Dione and fainter Enceladus off to the left. These transits only happen from our point of view when Saturn’s ring plane is nearly edge-on as seen from Earth.

Later this year, on August 10 and September 4, 2009, the ring plane will appear perfectly edge-on; however, we won’t be able to see that rarity because Saturn will be too close to the Sun for good viewing. These happen periodically though — in another 14-15 years we’ll get another chance to see the rings edge-on again.

Gaze at this image (particularly the large one)  for a while — note the faint banding in Saturn’s atmosphere and the sharp shadow of Saturn’s rings darkening the cloud tops.  For more information on the image and how the HST folks got it, check out the web site news release. It’s got details about the exposures used, the observation times and much more.

There’s even a nifty video sequence of four “eclipses” as the moons transit the planet.  You can see it here.

And, thanks to Andy Chaikin for pointing out that there’s an even COOLER pic of the transits on the Hubble Heritage site. Those moons are lined up quite  nicely!

A Hubble Heritage view of the Saturn transit. (Click to embiggen.)
A Hubble Heritage view of the Saturn transit. (Click to embiggen.)