I had a post in draft form wherein I mentioned that I was keeping my eye on the egg case of the Chinese mantises (Tenodera aridifolia sinensis,) figuring it was due to erupt at any time. This morning, that post was ruined.
I was just about to head off to meet with a student when I took a last look at the egg case, and found it almost literally dripping with newborn mantids. I quickly got the camera out of the car and did a quick, impromptu photo session, toying briefly with the idea of calling the student and postponing slightly. I decided to keep to schedule, so I shot in natural (brilliant) sunlight, trusting to the camera’s exposure meter, which was not the best of choices. I was using a different camera with, apparently, radically different base settings for contrast and exposure – believe it or not, this is at a setting with contrast and saturation intentionally lowered, specifically to use in bright conditions, and it was still off the scale. I tweaked the image a bit in Photoshop to make it more presentable, but this is far from what I would have liked to have captured.
Still, this is the first time I’ve gotten the actual emergence, and by the time I returned the action was over, so at least I have these. In the center of the image, marking the top of the swarming babbies, three mantids can be seen emerging from the egg case, which has the consistency of styrofoam, or maybe that expanding foam insulation stuff. They would draw themselves out like worms, legs held tight against their bodies, and stretch the legs out once free to slowly crawl down and join the mass of siblings, where they would pause for a bit to allow their chitin to dry and harden. One earlier emergent can be seen at the top of the egg case, scampering around cockily, while the hind end of another appears behind the emerging three. The dark spots are their eyes, and this hatching gave me a little more of a baseline in using their coloration as a guide, as we’ll see shortly.
Here’s another view, as one plays daredevil off to the side. Notice how the heads have swollen after hatching, with the eyes becoming prominent. The whole mass was writing slowly in an insectily creepy way, and every once in a while one of the firstborns would scamper up or down the column excitedly. I am not, at this point, sure of what exactly they’re hanging from; while it could be each other, right now there’s also a string of some kind of debris hanging from the egg case, so perhaps they were using that.
When I’d returned about four hours later, the young’uns had dispersed throughout the bush, and it took a few moments of careful examination to even spot one – then, abruptly, there would be several visible. They measure 10mm long at this point, and their coloration has become more what we’d expect, though they still stand out against the darkness of the azalea leaves. Their eyes have now blended in with their bodies, giving an indication that if you’ve found any with dark eyes, they really are newly hatched.
Considering that on March 7th, and again on the 18th, this egg case was coated in ice during the freezing rain storms, it’s somewhat weird that these guys are out now – not because they’ve weathered the cold, but because it doesn’t seem like winter’s actually past yet. I’m cool with all the signs of spring that are apparent now, including the first hummingbirds at the feeder, and it’s interesting to watch the ongoing family tree develop – this is the third generation of this genetic line that I’ve watched here. There are also the green lynx spiderlings still to be found, which I’ll be watching develop – most of these are a few meters away on the rosemary bush.
And then, there’s another generation soon to appear, and I’m going to horrify a lot of people by saying I have no intention of interfering, and hope to see the hatching. This will be a lot harder though, since mama put her egg sac under a wooden box out of sight, so I have to overturn the box to check on progress, something that I don’t want to do too often because I’d prefer not to disturb them frequently. Still, now that the egg case has appeared, I suspect the black widow mother will stay put regardless, and the newborns should be along pretty soon themselves. And yes, I’m almost positive this is the same one photographed last year. I’ll be sure to post any images of those babbies when they appear too, so you have that to look forward to. And should, because they look quite a bit different from the adult phase. Keep watching this space…
I threatened to do this, and after watching I felt more than obligated, so let’s talk about Your Inner Fish, a video program from PBS.
This one-hour program by Tangled Bank Studios is hosted by Neil Shubin, a self-described ‘fish anatomist’ from the University of Chicago, and based on the book of the same name. If you’ve read the book, the video will hold few surprises – but that isn’t why we watch videos, is it? And for the visual augmentation that is provided by such, PBS did an excellent job. CGI is present in a lot of things anymore, and ridiculously overdone in many cases, but here it was used judiciously and with great effect. Most of the program is straight video – interviews, set pieces, location shoots, and dramatizations – but mixed among them all, often overlaid on top, are graphics that illustrate the concepts and anatomy in a compelling and often dramatic way, but without going overboard at all. Fossils can be very hard things to merely spot, much less ascertain the details of, so the glowing outlines delineating their presence and shape are much appreciated, and manage never to get too obtrusive or distracting. Meanwhile, the virtual long-track across the curving tree of descent is both illustrative and expressive, taking a relatively simple subject and giving it a nice bit of flair.
We travel to the road cut in Pennsylvania, where the first discovery was made, and thence to remote and forbidding Ellesmere Island in the Canadian Arctic, seeing firsthand the conditions that greet fossil-hunters (and many other scientists.) But we also see the lab work, watching skate embryos swimming within their egg cases and the beating hearts of unhatched chickens. Overall, the visualizations kept pace with the details, always giving us something to see along with the information imparted by the narrative.
There were a few small exceptions. The actual developments spurred by the implantation of the sonic hedgehog genes were graphically portrayed, but not shown as real photos. There is an illustration of the tendons of the human hand, but not of the counterpart in Tiktaalik, despite indicating the broad attachment points for such. These are minor and largely up to personal preference; others might have wanted to see something else illustrated, or felt that what was included was more than adequate.
Another minor point was the solitary perspective, only noticeable early in the program. Shubin announces that, as a scientist, he looks at people differently, and in a few other places he speaks of what “I” do, in circumstances where these are shared by not just the scientific community (whatever that is,) but everyone who even holds a strong interest in the topics. It was a slightly uncomfortable distinction, separating the scientist from the viewer, and served no purpose, but thankfully it was brief (and not noticeable in the book.) Shubin is an entertaining and enthusiastic speaker though, so this is a minor detraction in an otherwise positive presentation.
The anti-evolutionist will not be convinced, unfortunately – a one-hour program covering a lot of territory isn’t going to provide the kind of rigor necessary, but then again, nothing would be adequate for a large percentage of creationists anyway; their desire is for self-indulgence, not real understanding. I’m not coming from a perspective that will allow me to judge, but overall, I got the impression that what was given in the program was a pretty enticing taste of what can be found, indeed in the book, but also with a greater study of the subject matter through other sources. It is one of the best ways I’ve seen science presented, beating out both incarnations of Cosmos, and appears well able to spur greater interest in pursuing some of these subjects. It also helps that PBS is marketing the book right alongside the DVD as a package.
There are two more installments to come, Your Inner Reptile and Your Inner Monkey, and right at the moment it does not appear that PBS has scheduled these yet – I will try to keep an eye on them and throw out an alert when they’re due to air. I will do the same if this particular episode gets run again. If you’re not inclined to wait (and definitely shouldn’t trust little old unconnected me to catch the later episodes,) there’s always the DVD – it might seem a little pricey, but this is PBS, and part of that fee is going towards supporting such programs free of idiotic commercial interruptions. Whatever it takes, however, I urge you to check it out – I doubt you’ll be disappointed.
So, I made that previous post, checked it out in draft form, including (as always) all links and the embedded video. Everything worked fine. Published the post, went to the blog home page, and for some reason, the video wouldn’t load.
Played around a bit, checked the embed code, went back to the host site, and found a new layout of their clips, including another copy of the preview one I embedded. Suspicious now, I checked the embed code of that one, to find it different from the one I had just used and checked. I edited the post to use that new code, and everything seems to be working now.
So it seems, in the few minutes between proofing my post and publishing it, they changed the layout and video sources on the program site. If they’d delayed just a few more minutes, I likely wouldn’t have known the video went dead after I posted. Timing is everything.
Damn, this is what comes from being out of the loop as much as I am. While I never hear about what every chuzzlewit celebrity is up to (which is a major plus,) I also don’t hear about promising new programs in time to give adequate notice. Case in point: Your Inner Fish, airing tonight on PBS.
That name should sound familiar, considering that I reviewed the book of the same name a few years back (and you’ve undoubtedly read every post I’ve ever made.) The author, Neil Shubin, is the host of this show, the first of a three part series – following behind are Your Inner Reptile and Your Inner Monkey. The first airs tonight (April 9th) at 10 PM Eastern Time on PBS. And I have to say, if the preview and Shubin’s writing are any indication, it should be pretty damn good.
UPDATE: I have no idea what they’re doing, but the video clip I tried to embed has gone back and forth in the space of an hour, currently giving me a “no longer available” error. If you get that, just click on the link further down to go directly to their site, which I highly recommend, since the previews are great.
Check out all of the clips on their site – it certainly doesn’t look like they skimped on production values.
Anyone familiar with hominid fossils will instantly recognize the incomplete skeleton they’re laying out in several places in that clip: it’s Lucy of course, Australopithecus afarensis, and yes, that’s really all we have of that particular specimen, which is actually quite a bit for that time period – for many others, we have only a handful of fragments, and a few even have just one bit. It’s easy to question whether one bit can tell us anything, but if it doesn’t match anything else we have, then it tells us that it likely belongs to a whole new species. By the way, Lucy is not the only Au. afarensis specimen we have, though it was for a while – we actually have bones from ten individuals, including a toddler.
Anyway, check out the program! I may be back with a review myself…
This is an extension of the topic tackled in a previous Composition post, because I felt it deserved a closer examination. So join me as we dive bravely into the seedy underworld of the cliché again.
The word itself has distinctly negative connotations, doubly so when there’s any connection whatsoever to the Art World (which is a peculiar-looking, off-balance planet that changes its own orbit just to remain unpredictable.) If someone looks at something that you’ve done and uses the word “cliché,” chances are it’s not a compliment. Combined with the artistic desire for originality, this can be enough to push someone into previously unexplored creative realms.
There’s nothing inherently bad about this, and indeed, it can occasionally lead to something really interesting. But not by itself. What should be examined is exactly why someone would want to do this, and what exactly they are trying to accomplish. Yes, there’s a lot of emphasis on doing something unique – you become the only person known for this, and the artistic style becomes synonymous with your name. This is a well-established method of garnering fame, income, and a fanbase, but it’s one of those things that gets misinterpreted very often – it’s not the only set of factors ever involved, and nobody seems to have any figures for how often it doesn’t work. Art isn’t just about doing something different, especially not when you’re hoping to accomplish any recognition for it; there also has to be the patron, the person (usually a lot of them) who gets a connection with what you do, who finds the shared spirit, who understands the mood you’re trying to evoke, who gets it. This is almost the exact opposite of individuality, even when it’s just a select few, an elite following. For someone to like your work, there needs to be a certain level of social interaction – not in the form of shaking hands or accepting a Friend request, but in the form of someone getting a positive response from your creation.
There are a lot of people who never seem to recognize this, who pursue individuality to the point of breaking down whatever social interaction is to be had – they create confusing, scattered, unrecognizable works that avoid a resemblance to anything else, including whatever kindred spirit they might have evoked from the viewer. True enough, they have avoided clichés, and derivative works, and thus established their uniqueness – but is that all that was desired? Does this mean anything, to anyone? Or is it just neurotic overreaction?
As indicated in the earlier post, clichés exist largely because something has become inherently recognizable – the empty playground swing that represents lost childhood, the monochrome photo of a smoking young woman in a café. They’re expressive – so readily, in fact, that they can be overused, which is how they became clichés in the first place. And it’s certainly true that if the viewer sees anything as a cliché, they’re not likely to possess a positive reaction to it. But we also can’t abandon every last vestige of recognizable elements in the obsessive desire to leave this epithet behind. What people like about art is the positive elements they find, not the mere lack of negative elements, or even the originality of the approach. Randomness, like paint from an overturned bucket or the leaf litter of the forest floor, is unique; obviously, something more is needed.
Quite often, what works is the balance point: the method or style that’s rare, combined with an ability to strike that common chord with the viewer. Don’t look at me, I make no claims of having accomplished this at all, and am not terribly motivated to either. A lot depends on what the goal really is. If anyone does anything at all that they show, to even just one other person, they’re looking for approval, and there’s nothing wrong with this. But approval can come from a lot of different things, and sometimes, it’s doing something very common. Current styles in just about anything relate directly to conformity, the desire for people to connect with as many others as possible, and this means you can occasionally make a lot of money by being able to provide this. Sometimes people want to see something dependable, even predictable – tally up the number of films you’ve seen with happy endings against those without. The things that spark our emotions are mostly very simple, as any advertiser will tell you – and hearing that will put countless artists on the defensive: “Don’t even try associating me with commercial advertising!” Such a perspective can be damaging if taken too far, because the human traits that the advertiser manipulates are the same traits to give an appreciation of anything artistic or creative, they just need to be summoned in a different way. Think of it from the standpoint of a chef; you can start with the ubiquitous base ingredients such as chicken or potatoes, but it’s what you do with them that matters. And to continue this analogy, fast food places do not exist because people solely crave originality.
It is important to recognize that ego likely plays a role in all this: “I want to start my own style.” Yet, this is no different from opinion, and everyone has one. What we want isn’t our own style, but for others to look at it and say, “Wow, what a cool style!” Or perhaps, even just, “Sure, I’ll buy that.” Ego is always stroked by others. While we might like to think others will come to us, it’s probably more useful to think in terms of bringing to others what they want.
Some of my most appreciated images aren’t unique, and some of them are downright trite – it’s not the originality at all, but just the emotions that are invoked, perhaps, “I want to be there,” or, “Those colors are gorgeous.” Other images are unique, in limited ways, by showing atypical angles or details, surprising people while still showing them mundane (sometimes even creepy) subjects. I’ll never claim to be accomplished at it, and I don’t do the artsy thing often, but I still get compliments on my work. Many of those would never have been forthcoming if I worried way too much about being truly original.
About a week ago, I noticed that another of The Girlfriend’s Younger Sprog’s flowers was of the type that opens each morning (when the conditions are right,) and started planning to try again to capture this. Naturally, the weather went to yuck for the next few days after that, but I watched for the promise of a clear warm morning and got set up early when it arrived. I learned that the flower (whatever it is – I’m yielding to laziness again by not looking it up) responds more to temperature than sunlight, and defiantly stayed closed and motionless for the 90 minutes and fifteen frames that the camera was dutifully snapping away before the day warmed sufficiently. After I packed up, of course, the flower bloomed.
So, as seen here, I tried again the next day and was a bit more successful. Scattered thin clouds made the light highly variable, most noticeable at the very end when the final frame is shot under haze, lowering the contrast and making it seem as if I’d altered the photo (I mean, beyond the resizing and format changes to make an animated gif [pronounced "fig"] in the first place.) This time I went with auto-exposure, but under-exposed a stop to keep the flower from getting bleached out, knowing the meter was reading more of the background than the flower itself – I should probably have gone for only 2/3 of a stop under, though. While a gentle breeze may have been at play too, the motion of the flower is not my doing at all, and why it was waving around is beyond me – the sun certainly did not move that far to support the idea that the bloom was following it. Yes, I could have been better at leveling the camera when I set up, but at least I kept the shadow of the tripod out of the pic this time.
Okay, okay, I stopped being lazy – I think these are Tulipa turkestanica, or Turkestan tulips, but that’s just a tentative identification (I wasn’t the one who planted these.) But I do have a positive ID on this next pic.
You have to appreciate the texture of these leaves. This is a Tulipa greigii, or red riding hood tulip. The leaves spread about 10cm, so the central blob of water is about 4cm, or 1.5 inches – I’ve never seen a surface so repellant to water, and I’d love to view it close enough for detail, but that would take a microscope I think. This isn’t the first time I’ve photographed the peculiar edge effect either, where it seems the only place water will actually adhere, and I can’t tell you anything more about it. I’m a photographer, not a botanist; I can tell you why the light looks the way it does and what f-stop was used (f16,) but the nature of leaves has to come from someone else. Or you can buy a print and I’ll look it up for you.
Today was apparently a great day for the arachnids to venture out. At times, the light was just right and the yard could be seen crossed by numerous strands of web from the spiders ballooning to new locations, and I actually had two different species suddenly appear on my arms – dog knows how many might have landed on my shirt where I couldn’t feel them (or my hair – I said that just to creep you out, even though it’s as likely as anyplace else.) The butterfly bush, sprouting just two new leaves of the season, was heavily rigged with lines from this little spud, some species of Theridiidae I believe. Likely the same species found here, on a plant not a dozen meters away – probably not one of the ones pictured in that post, but quite possibly a relative. I found all the webbing and started looking for the responsible party, suspecting it was one of last year’s newborn green lynx spiders, and the increasing number of web strands and a tangle of protective canopy pointed out my tiny subject. That’s one of those tricks if you’re looking for arachnid subjects: the webbing is densest in the high-traffic areas. You can see the shelter out of focus behind the spider – this is shot aiming almost straight up. For scale, I can tell you that this one is even smaller than the green lynx spiderlings (Peucetia viridans,) and I can provide a photo of one of those on my thumb. We’re talking tiny here.
The biggest difference is, the lynx spider will get significantly bigger while the Theridiidae won’t – it might even be an adult. Well, okay, that’s probably not the biggest difference from an entomological standpoint, so let’s just say that this scale comparison isn’t going to last for long. The lynx spider may achieve a body length slightly longer than the first joint of my thumb, big enough to be ‘skeery’ (due to the prevalence of arachnophobia, this should not be considered a scientific description, since the word has been applied to widely disparate sizes of spiders.)
The rosemary bush that several of the lynx spiders have made their home, at least for now, also plays host to several specimens of sheetweb spider. These make a horizontal, very dense base web, often pulled down into a rough bowl shape, and a tall enclosing structure above, less dense and distinctly triangular in shape. When coated in early morning dew, they put me in mind of a sailing ship, with the base web forming the hull of the boat and the upper structure serving as the rigging. Often these webs are most easily spotted in dewy conditions or during a misty rain, and several times the snows of the season pointed out how many of these spiders were actually living on the bush. Yesterday and today I got a few images of one, proving that they have already started feeding, in this case on an eentsy little leafhopper. I’m fairly certain this is a filmy dome spider, Neriene radiata – probably twice the size of the lynx spiders right now, but also unlikely to get a lot larger.
What I’m pleased about capturing, in both images, is a particular detail of the web. The haphazard nature of the sheet is clearly visible, as are some of the anchor lines that draw the sheet taut and downwards, providing the bowl/hull shape and coincidentally illustrating the warp of spacetime at a black hole. If you didn’t get that, some day you will…
If you think the sheet looks too dense to allow the spider to slip through to the other side, you might be right. I just looked closely at the original image, the top one of the composite above, and I’m almost positive the leafhopper sits above the sheet while the spider sits below, reaching through the surface to feed. If this is typical, it implies that the spider does not bother wrapping its prey but counts on the venom to immobilize it instead. I’m going to have to keep a close eye on these now to see if this repeats, but that’s going to be a little tricky – the webbing defies easy depth-perception and it’s hard to tell which side anything is on, while the locations that the spiders have chosen for their lairs, purposefully I imagine, do not allow a wide range of camera positions. We’ll see what happens.
I am contrite over not posting much (and the complaints are pouring in,) but between several projects, bid sinuses, and no motivation to write, those last two largely being related, I just haven’t been able to get anything out. I have a few things in draft form, just not too close at the moment.
Meanwhile, zefrank returns with another True Facts video, this time about The Octopus – despite the footage he uses, he seems to think there is only one specimen of any animal he informs us about, for some reason. Maybe he’s picking one that is the quintessential example of the species. Isn’t ‘quintessential’ a great word? Use it in a sentence every day and you’ll automatically feel better…
As I’ve remarked before, zefrank’s definition of ‘true’ is not exactly Oxford’s, yet closer to it than the usage of ‘true’ by UFO proponents, alt-med enthusiasts, and the religious.
When I was in Florida and ‘maintained’ a saltwater tank, I would have loved to have had an octopus, if only for a day or so for photos, but I really didn’t have the equipment for it – they’re high-maintenance critters. They remain on my list of things to encounter personally, one way or another, but until I’m actually doing scuba trips this is unlikely, except for the local Chinese restaurant (“alive” is one of my incredibly specific criteria, demanding as I be.)
Anyway, more will be along shortly.
While skimming through images in my folders, I came across this pair taken back in 2012, and decided to feature them to appease all of the people who started coming here because of the bugs, who now have nothing to see during the cold months. You haven’t been forgotten.
On the spearmint flowers this butterfly, likely a pearl crescent (Phyciodes tharos,) was holding a little too still – they might often pause and sun themselves, occasionally fanning their wings slowly, but won’t typically allow this close an approach. Not to mention that the wings aren’t held in a natural position. The faintest clue can be seen to the left of the butterfly if you look close, but the real explanation came from lying on the ground below and shooting up from underneath – this next image still sparks the memory of a damp shoulder obtained from not using a ground pad when I got the shot.
It will probably help if I explain what you’re seeing here, since it’s an odd angle and much is obscured. The most noticeable aspect is the pale, dimpled abdomen of a crab spider, most likely a white-banded crab spider (Misumenoides formosipes) – its cephalothorax (head) is partially hidden behind the butterfly it is gripping. You’re seeing the butterfly tail-first from below, the abdomen out-of-focus in the center of the shot since I was after the spider; one wing goes into the top right corner, the other down the left side. Not the best illustrative angle, which may be why I never bothered to feature the images back when I got them, but there’s a real limit in many situations. The spearmint plants were not very tall, and to get a perspective that showed the spider at all required shooting almost straight up from flat on the ground, with no opportunities for other angles. The lighting is deceiving, since it comes solely from the flash – in ambient sunlight this would have been in deep shadow. Trying for anything else might have resulted in disturbing the subjects, which could have made the spider discard its meal and scamper for cover.
The spider probably has a grip on the thin neck of the butterfly; this seems to be a very common trait of spiders, likely because it provides the best access to internal fluids. Arthropods don’t really have blood vessels, but instead an open circulatory system – this means the ‘blood’ (actually hemolymph) runs freely throughout the body cavity. Yet there are still organs that ensure that the hemolymph reaches the head, and it might well be this that the spiders tap into; it could also be that their venom works most effectively when applied here, eradicating struggling quickly. I’m not an entomologist, so this is only speculation, but the grip in this area is something I’ve seen dozens of times.
Another example is provided by the same species of spider from this past summer, an image I dug out while writing this post – yes, they can change their coloration to match the flowers they conceal themselves within.
Unless it’s very early morning after a chilly night, bumblebees never hold still, and certainly not in this position, so it was a dead giveaway that something else was happening. At least, it is to anyone who takes a moment to think about insect behavior – this was in the NC Botanical Garden, and plenty of people were walking past and paying no attention to this tableau at all, though some of them might have been there for the flowers and not the bugs. I know, right? There’s no accounting for taste…
There are a few minor photo challenges that remain in the back of my head, waiting for the right opportunity to tackle them – some of them are inconsequential, hardly anything to catapult me onto the pages of National Geographic or even The Daily Mail. This is one of them.
I mentioned before that I’ve long wanted to capture the sunrise on the central peak of the lunar crater Tycho, which takes some pretty specific timing, not all of which is within my grasp; despite the length of lunar days, the ideal moment may still occur when the moon is out of sight behind the Earth. But it also occurred to me that perhaps I could get sunset instead, and so I’ve been keeping this in mind too.
A brief bit of the physics involved. Tycho sits very close to a central position on the moon, when seen from our vantage point on Earth, so sunrise and sunset therein will take place at either the first quarter (half moon, heading towards full) or last quarter (half moon heading towards new.) This means the sun is either leading the moon into our sky by roughly six hours, or trailing it by the same amount – it has to be shining on the moon from the side (again, according to our vantage.) So the moon will rise about six hours behind the sun for Tycho’s sunrise, and be visible for half of our day and half of our night. For sunset, the moon rises six hours before the sun and, again, be visible for half the night and half the day.
This means Tycho sunrise might be captured in the evening before midnight, but sunset has to be well after midnight – in this case, around 4 am for the moon to get high enough not to be obscured by trees, or dimmed by thicker atmosphere. I was up pretty early this morning (I have a weird sleep schedule anyway) to get the shot above.
And yet, still missed it. Tycho can be seen as the darkest crater about one-fifth of the way up from the bottom, sitting right on the terminator (line of shadow) – not that big crater, but the much smaller one that looks like a hole. The entire crater floor, including the central peak, is shrouded in shadow, and the sun is only hitting the top edge of the far wall. I had been out the previous morning, and the shadow was well away from the crater, so this morning was the best time I could arrange, but it was too late.
I even took a quick look at the images I’d gotten soon after moonrise, when it still wasn’t free from obscuring trees, and there’s no indication of the peak in those either, so it seems sunset on that peak occurred while the moon was someplace below my horizon. At least I tried.
Now, if I was much more capable of math than I am now, I could possibly calculate the exact time period when the peak will remain in the light while the crater floor is shadowed. I’d also have to be more obsessive than I am now, so it ain’t gonna happen. I imagine someplace online, someone has already worked it out, but I’m going to yield to laziness right now. Snark all you want – I was out twice in the wee hours of the morning, ice crystals crunching under my feet, just to get these images. For nothing. Nothing!
But here’s another perspective. While on the moon, there is no Earthrise or Earthset – not in most fixed locations, anyway. The moon is tidally locked with Earth, meaning the same side faces Earth all the time – mostly. There’s a slight wobble. But anyplace within Tycho, the Earth remains high overhead. It changes phases, just like the moon does for us, but there’s never a dark night in Tycho. When the sun is below the horizon, the Earth is at least half full, and when the Earth’s phase drops down to a crescent or less, the sun is high in the lunar sky. A ‘full Earth’ occurs in the middle of the lunar night, and a ‘new Earth’ occurs during lunar midday – this means that Earth goes through all phases in the course of one lunar day/night cycle, which averages 29.5 Earth days long.
The classic photo of Earthrise, taken by Williams Anders during Apollo 8, occurred because the Apollo spacecraft was orbiting the moon – that’s the only way to see this. Almost. There are some locations on the moon that do see Earthrise, just by the barest amount, because of that aforementioned wobble (technically, “libration.”) From our vantage, they sit in a narrow band that marks the outer circumference of the moon, the limits of what we can see from Earth, and the libration means that the Earth peeks just barely above the horizon once a lunar day. While the far side of the moon, never seen from here, also never sees us.
If you saw the caveat that the lunar day averages 29.5 Earth days in length and wondered about it, that’s another curious aspect of the orbital mechanics, and a demonstration of relative measurements. Picture the sun, moon, and Earth laid out on a grid, surrounded by stars. For now, we’ll consider the sun fixed on the grid among the stars, while the Earth orbits the sun and the moon orbits the Earth – the Earth, at the same time, is rotating to produce its own day/night cycle. The moon is rotating itself as it orbits the Earth, but mostly keeps one side facing Earth – its orbit and its rotation are synchronized, except for that libration.
The moon completes a full rotation, measured by that grid, in a little over 27 Earth days – but because it’s riding along as Earth orbits the sun, that isn’t enough to complete a day/night cycle on the moon; the Earth is almost one-twelfth of the way along on its own yearly orbit of the sun, and so the sun angle is slightly different now, and it takes another two days or so to complete that light cycle. Yet, this varies, because Earth’s orbit around the sun isn’t a perfect circle, but an egg-shaped ellipse with the sun off-center, and as it draws closer to the sun, it actually accelerates in its orbit a little, slowing back down as it draws farther out in the course of the Earth year. The moon is dragged along in this acceleration/deceleration cycle, so the lunar day changes length slightly in this time too.
Makes you realize how much we’ve simplified terms like “day” in the face of the physical actions of orbits and rotations. Astronomers have lots of specialized terms to pin down what, exactly, they’re referring to at any given moment.
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