Starship Asterisk*

by **bystander** » Mon Oct 22, 2007 2:42 pm

In the description of the apod, it is stated

The above image was taken near Jupiter's terminator

That along with the "above image" url confirm it is the terminator.

by **Qev** » Tue Oct 16, 2007 1:02 pm

The "above image" link in the APOD description leads to the New Horizons page for this image, where it appears to confirm that this is the terminator that we're seeing.

by **starnut** » Tue Oct 16, 2007 2:00 am

iamlucky13 wrote:It might be the terminator, but it seemed very abrupt to me...it doesn't seem to fade gradually as the sunlight strikes at increasingly oblique angles, but I guess that could make sense if, as auroradude suggested, they selectively brightened portions of the image. I'm also not used to seeing smooth terminators (think craters on the moon), but now that I look a little closer, I see there seems to be a little unevenness corresponding to the bands that may reveal slightly different cloud heights.

I am also wondering why there is no shadows of the cloudtop and reddening casted by the setting (or rising) sun near the terminator. It would have been a more dramatic image if they were left in instead of being doctored.

by **geckzilla** » Mon Oct 15, 2007 10:35 pm

I get the feeling the edge of the actual composite image was more like a bunch of photos laid on top of each other so it had a boxy edge but rather than show that, they added the dark arc to cover it up. I think I might have preferred it with a more natural looking terminator.

by **iamlucky13** » Mon Oct 15, 2007 7:24 pm

It might be the terminator, but it seemed very abrupt to me...it doesn't seem to fade gradually as the sunlight strikes at increasingly oblique angles, but I guess that could make sense if, as auroradude suggested, they selectively brightened portions of the image. I'm also not used to seeing smooth terminators (think craters on the moon), but now that I look a little closer, I see there seems to be a little unevenness corresponding to the bands that may reveal slightly different cloud heights.

I passed over the mention in the caption that the image was "near" the terminator on my first read. It seems the image is not just near the terminator, it's of the terminator.

You'll also notice the top of the image is a little darker. I'm not sure what to think about that either, but it's much less dramatic.

by **hughhyatt** » Mon Oct 15, 2007 5:34 pm

Anybody know what the prominent shadow at the bottom of the image is.

You aren't talking about the terminator, are you?

by **auroradude** » Mon Oct 15, 2007 5:26 pm

I was also having problems trying to interpret the bottom of the image.

I'm not sure of the angle that it was acquired but possibly the spacecraft was looking at a "1/4" Jupiter from nearly 90 degrees above the terminator. This would render the terminator nearly straight.

It also looks like there is more noise or banding towards the lower edge so this might indicate that the "ISO" was cranked up to even out the shadow and pull more detail from the darker areas.

This banding in the terminator area (not the wave-like patterns seen in the less turbulent zone) is possibly is the result of the type of imager. It probably scans narrow lines to build a complete image and as the brighness is adjusted for deeper and deeper shadow the scan lines to not match up as well as if the brightness were constant. This adjustment also could easily have been and most likely was made, post-production.

by **iamlucky13** » Mon Oct 15, 2007 4:38 pm

Yes, those are some kind of artifacts, although I'm not sure what kind. They're not hot pixels and don't really look like over-saturation lines. They might be noise introduced during transmission of the data to earth.

And the ripples are cloud structures, as there is no solid surface on Jupiter. It's fascinating how much they look like transverse dunes, though.

Anybody know what the prominent shadow at the bottom of the image is. Surely that's not the edge of the planet? As I understand it, this covers a signifant portion of Jupiter's latitude, so it doesn't curve nearly enough to be the edge. And it doesn't soften like the edge of spherical objects usually seem to. Perhaps I'm just having trouble with the scale, though?

http://en.wikipedia.org/wiki/Image:Jupiter.jpg

by **hughhyatt** » Mon Oct 15, 2007 3:54 pm

I notice some light-colored—possibly yellowish—horizontal streaks and spots, most prominently near the terminator toward the right (North) end of the image. I assume these are photographic artifacts. Just the right of center I see some ripples like one might find in a dry riverbed or along the beach. I assume these are cloud structures. Are these assumptions correct?

Thanks!

by **Qev** » Mon Oct 15, 2007 2:29 pm

This article seems to indicate that windspeeds continue to increase with depth in the Jovian atmosphere. Speeds over 640km/h are pretty much certain at depths of over 90km. In the zonal bands, typical speeds seem to be around 360km/h.

by **orin stepanek** » Mon Oct 15, 2007 12:43 pm

http://antwrp.gsfc.nasa.gov/apod/ap071015.html

I was intrigued at the close up New Horizons was able to capture on it's fly-by of Jupiter.

Orin

by **Alietr** » Mon Oct 15, 2007 12:37 pm

Does anybody happen to know the speeds of winds in the cloud bands shown in the picture? Which bands contain the higher speed winds?

Thanks.

Starship Asterisk*

Jupiter's Clouds from New Horizons (APOD 15 Oct 2007)

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Prominent shadow

Streaks and spots?

Jupiter's Clouds from New Horizons (APOD 15 Oct 2007)