Ceres: Just a little bit closer (and officially better than Hubble)
Last week's Dawn images of Ceres were just slightly less detailed than Hubble's best. This week's are just slightly more detailed. Detailed enough to be dangerous. It's very tempting to talk myself into interpretations of the various light and dark splotches visible in this latest animation -- I see double-ringed craters, arcuate ridges, and a smattering of bright dots that I want to call fresh impact craters. But since Dawn's getting closer every minute, I'm going to refrain from drawing any conclusions for a little while! In the meantime, let's just enjoy the images.
Here's the animation more or less as released by the Dawn team -- I aligned it and tweaked the levels a little bit:
NASA / JPL / UCLA / MPS / DLR / IDA / Emily Lakdawalla
Dawn's view of Ceres on January 25, 2015 (animation)
This animation is composed of 20 images gathered over a period of about an hour for optical navigation purposes. Dawn was 237,000 kilometers from Ceres at the time.
Just for fun, let's compare it to the view from January 13:
NASA / JPL / UCLA / MPS / DLR / IDA
Dawn optical navigation sequence on Ceres, January 13, 2015
Dawn took the 20 images for this animation on January 13, 2015, in its first lengthy optical navigation sequence on asteroid 1 Ceres. Dawn was 383,000 kilometers away at the time. The images in this animation have been aligned and contrast-adjusted.
As he did last week, Björn Jónsson took a subset of the frames from the animation, reprojected them to a common map projection, stacked them, and then reprojected the result to give a super-resolution view of the globe. It's lovely work. But I think I'm still going to put off expressing opinions about what I see. We'll get to watch these features grow and come into focus over the next few weeks. I can be patient for that much longer!
NASA / JPL / UCLA / MPS / DLR / IDA / Björn Jónsson
Dawn's view of Ceres on January 25, 2015 (super-res stack of 9 images)
This image of Ceres is composed of 9 frames from the January 25, 2015 optical navigation movie, stacked and then sharpened in order to reveal sub-pixel detail.
If the images look blurry to you, it's because they've been enlarged. The Dawn team did release still images, one each from January 13 and January 25, showing just how much of the Framing Camera's field of view Ceres presently occupies. It's not much: 27 pixels in the first, and 43 in the second. In both cases, that beacon of a white spot on Ceres is essentially just one pixel. That means it's rather small, and really shockingly bright by comparison to the rest of Ceres' surface.
Shortly after these images showed up online, Ted Stryk pointed out an interesting similarity, which I shared on Twitter:
Pretty striking similarity, eh? To be fair, a lot of things in the solar system look similar when they occupy less than 50 pixels' width on your camera detector. The comparison does make me wonder whether Ceres will continue to look like Umbriel. Whether or not it does, I wonder what Umbriel would look like if we sent a modern camera on a spacecraft that could enter orbit at Uranus to photograph it. We need a mission to an ice giant!
NASA / JPL / Ted Stryk
Umbriel (2013 version)
This view of Umbriel was composed by stacking Voyager 2's best two images of it, and coloring it using images taken from a greater distance.