Saturn Glows Like Burnished Gold; Comet Encke Grows A Tail

Natural color view of Saturn photographed by NASA’s Cassini Orbiter on Oct. 10, 2013. The main rings – C (innermost), B (widest and brightest) and outer A ring can be seen. The bright, wavy arc of clouds may be the aftermath of a large storm that climaxed in 2011. Click to enlarge. Credit: NASA/JPL-Caltech/SSI/Cornell

Wow, what a perspective! The Cassini Orbiter took this photo – a mosaic of 36 images made through three color filters – on Oct. 10 from a highly inclined orbit that lets us peer over both the north and south poles of the ringed planet. Since Earth and Saturn are both stuck in the same flat plane of the solar system, we can never see the planet from the top-over perspective Cassini can.

Closeup of Saturn’s north polar hexagon. It’s 15,000-miles (25,000 km) across and contains many individual storm cells. Credit: NASA

Three main rings are visible – A, the outermost, B, the widest and brightest and C, the innermost and barely visible hugging Saturn’s disk. Cassini normally orbits the planet in its equatorial plane, where most of Saturn’s rings and its moon are located, but mission control directed the probe into a highly-inclined orbit for studies of its polar regions and magnetic field. Also tipped our way is the mysterious polar hexagon, a 6-sided wave pattern in the clouds centered on Saturn’s north pole.

Cassini doesn’t carry the fuel to change its orbit on its own. Instead, NASA pumps up its orbital inclination by stealing gravitational energy from Saturn’s largest moon Titan. Several Titan flybys, one building atop another, are enough to send it reeling over the poles at an inclination of 62 degrees.

When Cassini arrived in 2004 it was northern winter and Saturn’s clouds had a bluish tint. Nine years later, it’s early summer in the northern hemisphere and the clouds are distinctly more butterscotch-hued. Investigations have found that Increasing ultraviolet light from the sun creates a yellowish haze. During the winter season, when sunlight is less intense, the haze clears, letting us see further down in the atmosphere where the molecules scatter blue light like they do on Earth, giving Saturn a more bluish tint. The blue is further enhanced by methane gas, which absorbs red light.

Two weeks earlier amateur astrophotographer Gordan Ugarkovic made his own Cassini montage of the ringed planet. It appeared on the Oct. 21 Astronomy Picture of the Day. Take a look – it’s a beauty.

Comet Encke looks like a blue snowball with spike-like tail in this photo taken on Oct. 31. A bright galaxy glows at upper right. Credit: Michael Jaeger

Ready for one more succulent image? This one has nothing to do with planets. It’s Comet Encke in the morning sky taken by Michael Jaeger of Austria on Oct. 31. Encke is currently visible in binoculars in the constellation Virgo and trails a long, flagellum-like tail of glowing gases called an ion tail. As it approaches perihelion on Nov. 21 it’s becoming brighter and more active. We’ll have more on how our four morning comets are doing soon.

14 Responses

  1. Norman Sanker

    Hey Bob,

    It’s raining in Tucson–can you believe it? Yesterday morning I searched for all 4 comets but could only find Lovejoy which was plain in my 9X35’s after finding it first in the C-8. My chart savvy is shaky at best but I’m getting a better grip as I study your excellent maps (thanks!) and re-familiarize myself with that eastern, pre-dawn sky. So, for anyone else who might be getting discouraged: try for Lovejoy high in the south well before dawn. My eastern view is not as dark but I’ll see those other three eventually or go blind trying. I suppose that ISON will be obvious on the SOHO (?) website at perihelion–any thoughts on that? Thanks again and keep up the great work.

    Norman Sanker

    1. astrobob

      Thanks for sharing your hunt. ISON’s still lagging but should soon be visible in binoculars. I’ve heard of others seeing Encke and X1 in 50mm Vinod but suspect they were under very dark skies.

  2. Astrojohn

    Hello Bob,
    Great information as always. Have you by chance looked at Mars lately? Or do you have any recent (after Oct 1st) pictures of Mars? I have multiple scopes/lenses and my images are really quite troubling. I am hoping a pro like yourself can ease a Superior natives mind. I have searched the internet high and low. All recent photos I find look exactly like mine, very weird.
    Thank you for great articles and knowledge. You are an inspiration to us all.

    1. astrobob

      Hi John,
      I’m not surprised you’re struggling with Mars. It’s still very tiny in a scope. Only the astrophoto experts have squeezed a few decent images from it. I’ll try to post acre soon.

      1. Giorgio Rizzarelli

        Also to add, Mars’ angular size depends on the distance from Earth which is much variable. Next spring March will be at close approach and you’ll probably be able to see more. Best wishes

      2. Thank you for the info Bob. I really look forward to seeing what you can come up with. I wouldn’t necessarily say I am struggling with photographing Mars, more so it looks different since Ison’s passing. The photos on my site might shed some light into what I mean. They are in chronological order. The first few images I took in July, it looked round up until Sept. Then bad weather conditions made it unable to view until the middle of October here. The last few images were from last Sunday morning. All are taken from my 8″ and 5″ refractor and Newtonian scopes and they are unstacked images. Can you make any sense of this? Thanks again, Sir.

        1. astrobob

          It looks to me like mostly focusing problems and maybe some bad seeing. Anything change focus-wise between July and recently. If anything, the recent images should be clearer because Mars is slightly larger than in July.

  3. Giorgio Rizzarelli

    Hi Bob,
    Thanx as always for sharing. The Saturn image is amazing.

    I’m getting binoculars on tripod and would like a suggestion from you about the ideal magnification factor. I don’t want to spend much, just want something to fill the “low magnification / wide field” zone (as you know I already have a scope), to see things like M31, comets, and hopefully galaxies/nebulas with maximum light. I’m keeping the eye on a couple of good quality/price 70mm aperture models, and I have to decide between 11×70 and 15×70. Both popular combinations for astronomy, someone suggested to me the 15x for the more magnification. The 11x, which in theory has about double light respect the other, really has just 50% more, because the exit pupil is in practice limited by the age of my pupil size: the main difference of the 11x is the wider field, which makes more easy to find objects (and posibly it can e also used handheld for naturalistic use). Price and weight (1.3Kg) of the two are equivalent. Which of the two would you suggest? Thank you very much

    1. astrobob

      Not an easy question but with the extra FOV and ability to handhold I’d give the 11x70s the edge. You’re still fairly young, right? A slight loss of exit pupil should be tolerable. I used to have pair and they were wonderful on brighter comets.

      1. Giorgio Rizzarelli

        Thanx Bob. You’re right, the loss of exit pupil is small: The pupil-age curve I had found on web is oversimplified (a linear approximation, too crude), I now found better curves and data. Thanx for letting me realize I’m not that old, you made my day 😀

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