How does the image of Earth taken by Cassini compare?

[willpittenger]

Back in the 1990's, Voyager took a series pictures of the solar system from well past Neptune's orbit. The image of Earth was roughly 3-4 pixels. How does that compare in angular resolution to the one that Cassini just sent back? (see the latested image at http://i.a.cnn.net/cnn/2006/TECH/space/09/20/saturn.ring.reut/story.earth.from.saturn.jpg.) <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[qso1]

I recall the Cassini image referencing the colors. The image appears grayscale to me. I'd chalk it up to color blindness but I see everything else in color. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[baktothemoon]

Is that the moon on the upper left side?

 

[willpittenger]

Actually, the CNN version of the image looked overexposed to me. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[qso1]

I saw the image on space.com and it looked about what I would expect for a spacecraft imaging a target that far away but it was grayscale or what we used to call black and white. It may have been overexposed and what I recall of the Voyager image was that it had to be greatly enhanced to even see Earth. But as I'm sure you already know, Voyager was much further away when it took its image of Earth. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

baktothemoon:<br />Is that the moon on the upper left side?<br /><br />Me:<br />Unless it was a defect in the image, I'd say it was the moon. In fact, when Pluto is imaged by ground based instruments, its moon Charon appears similarly. Only Hubble has imaged the Pluto Charon system as distinct separate objects. I havn't seen images of that system with the Keck or ESO telescopes so I don't know if they can resolve them as separate objects.<br /><br />One way to verify the object is to use Starry Night to view Earth/moon from Saturn and see what position the moon is in although the Cassini orientation would have to be confirmed as well. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[willpittenger]

I just assumed the Moon was partially behind the Earth or too small to show up. How many pixels would have been needed at this distance? <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[qso1]

The moon might have been behind the earth which was the reason I commented on using Starry Night to verify the moons position. You could use the JPL solar system sim as well but its a bit more complicated to use. I don't have the answers to the pixel questions but the general appearance of the earth in the image is consistent with what I recall of pre-hubble Pluto Charon images. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[CalliArcale]

According to the captions released with the image by the Cassini team, that is indeed the Moon peaking out from behind. The relative brightness compared to the Earth looks about right; the Moon is much dimmer than Earth (which is shiny because of all the water). And it is indeed part of a color image. The extreme closeup, however, is not in color; it's a monochrome image.<br /><br />How can part of the big portrait be monochrome while the rest is color? Simple. The big portrait with Saturn was made by combining several monochrome images taken through different filters. For the extreme zoom-in image, they didn't bother with that and just used one of them. So yes it's monochrome and yes it's color! <img src="/images/icons/wink.gif" /><br /><br />The full portrait <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[qso1]

Thanks for that link and confirmation of the moon in the image. I didn't get to see the color wide shot image when I initially posted. That is a really cool shot too. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>