New pictures of the surface of Mars, taken by the Mars Reconnaissance Orbiter. They’re interesting — what looks like water eroded canyons, very familiar, and exotically odd things like cones of snow produced by windblown eruptions of geysers.
One thing I wish they’d do, though, is either tell us where the light source was, or be consistent in their orientation — I learned early on that you need to lay out photomicrographs of DIC cell fields so it looks they are lit from the top of the picture, or otherwise you get ambiguous shadows that can make cells look like craters rather than plump bumps. It’s the same problem with these photos — half of them, I can’t tell whether I’m looking at a canyon or a hill, and worse, they flip between the two states as I’m looking at them. Don’t people using telescopes have conventions to accommodate human visual perception quirks, just like us people who use microscopes?
“Don’t people using telescopes have conventions to accommodate human visual perception quirks, just like us people who use microscopes?”
No. Probably because astronomers are accustomed to photographing stars and galaxies, and orientation really doesn’t matter for those.
Astronomy: Where orientation doesn’t matter. :P
These are planetary scientists, not astronomers, acquiring these images. And yes, there are conventions for annotating the sun (or illumination) angle, but they are easily overlooked and either not added as image overlays or dropped by re-editing figure captions, not including the metadata in captions, or dropping the captions entirely.
There’s other conventions, such as North is Up, which conflict with Light is Upper-Left. Unfortunately, there’s yet other conventions such as South is Up or The First Scanline is Up (which is largely equivalent either to North or South, but you have to read the metadata to find out which).
The general convention for telescopic imaging is to have celestial north at the top of the frame and east to the left, at least in the northern hemisphere as that mirrors the sky. However the sky is “upside down” south of the equator so any such orientation is completely arbitrary. The reality is that for most extra-solar system objects the orientation is only important with respect to other nearby extra-solar system objects.
Why are those Martian Landscapes “ancient”?
Jason @ 5:
Yes, and in itself it’s a perfectly logical convention, but when you look at a terrestrial globe, if north is to the top, east is to the right, so astronomers’ east-west convention is reversed relative to geographers’.
I’ve often wondered whether optometrists have a similarly confused lateral sense as a result of spending their working lives looking at charts labelled R —- L ;-)
I just thought I’d use this post as a flimsy excuse to mention that The Martian by Andy Weir is a very enjoyable read.
If you are looking at cells, don’t you already know everything should be a bump and not a depression? Planetary surfaces have both in abundance, so I don’t know if there would be a way to trick your brain into perceiving it correctly. They use stereoscopic images to resolve these kinds of issues.
The landscapes are ancient because Mars has neither plate tectonics, nor frequent global volcanism to resurface or rework the planetary surface, and meteor bombardment is isn’t doing it at any great pace these days.
These images weren’t taken with a telescope, but rather with a camera onboard an orbiting spacecraft. There’s no standard or convention for illumination angle because it changes constantly as the spacecraft orbits Mars. If you go to the original image page though (for example: http://www.uahirise.org/ESP_038646_1805), and scroll down, you’ll see all sorts of information about illumination, incidence angle, longitude, etc…this info just doesn’t tend to get reported when folks write about the images on their blog or news site.
that is one the things I dislike about photos like these while the details are stunning and dense I have a hard time telling what they actually are. My mind just ends up seeing them as abstracts.
I for one would really appreciate it if they at least sometimes included a summery of the associated data.
uncle frogy
Chigau, Because unlike Earth, Mars has not had any large scale resurfacing or erosional activity for thousands of millions of years.
richardh, when looking at Earth on a map, you are looking down at it from above, while looking to the heavens requires looking up from below, or perhaps out from within the celestial sphere.
It’s a whole other world. It’s why I wish we’d either pony up the money for more robotic landers or bite the bullet and do a manned mission there – our ground robotic explorers have covered only a tiny fraction of the overall surface, and that of a planet that’s close to Earth in cosmological terms.
BBC reports that the Curiosity Rover has figured out the mystery of the multi-layered Martian mountain.
@brett #15:
Sadly, as things stand, a manned mission to Mars would be more like eating a bullet. Think of how many Apollo missions it took before Apollo 11 was considered to stand a better than 50-50 chance of the crew returning alive. We don’t face so much of a rocketry problem now, but surviving two long space trips and managing a successful Martian descent and ascent are still very tricky problems.
I just thought I’d point out that Brandenburg himself started posting to the Sb version of PZ’s post about his paper in the Journal of Cosmology.
Cydonia hypothesis, woo!
The same thing that terrestrial imagers use, anaglyphs and stereopairs. https://hirise.lpl.arizona.edu/
I downloaded some Curiosity images and turned them into stereo views that work with old-fashioned stereograph viewers. They’re really quite striking. I’ve uploaded them to my website if anyone is interested.
Mars 3D
Moggie,
seconded.
BTW the breakthrough with pattern-recognition computer chips (see “TrueNorth” chips) would make it possible for Mars rovers and other robotic missions to be more independent of flight control -very important considering the looong time lag.
I doubt we will see non-conventional thrusters (such as VASIMR) but better, independednt computers will make it possible to load up with rocket fuel (“in situ propellant production”) at a landing site before the first astronauts arrive. Which is what Robert Zubrin suggests.
kc9oq, thanks for the stereo pairs.
I can view such pairs without a viewer, thanks to my near-sightedness. I take off my glasses, hunch up close, and wait for focus. (The pairs have to be “wall-eye”, and no further apart than my eyes are.) Other folks might like to give that a try.
Indeed. That’s why it’s a perfectly logical convention. But what happens when astronomers look “down” at a non-Earth object? When people last walked on the Moon, if they faced Polaris was lunar east to the left or the right?
And let’s not get into the fact that Earth’s northern magnetic pole is a “south pole” and vice versa ;-)
#22:
Yes I can do the same thing and I think with a little practice anyone can train their eyes to view stereographs without an apparatus. I collect old stereo views and can go through a bin of them at an antiques shop & evaluate them without a viewer.