A real-time Earth orbit

I still remember that when John Glenn, the first American to orbit the Earth, did his three circuits in 1962, it took about ninety minutes per orbit. Apparently that’s still the case, and this video, made from photos taken by the International Space Station, shows a complete orbit in real time. It’s 92½ minutes long, and mesmerizing.  You might just want to put it on your screen (leave the music on if you won’t give yourself away!) and let it roll.  Matthew, who sent it to me, gives more information:

Made by Seán Doran using NASA images (with a Joyce quote at the beginning). Crank up the sound and watch in full screen, (lasts 90 mins!) Spot the geographical locations, too.

Extra points if you identify the Joyce quote, and super-extra points if you give its significance in the book. Oh, and look below the video for more information from YouTube.

More stuff;

Orbit is a real time reconstruction of time lapse photography taken on board the International Space Station by NASA’s Earth Science & Remote Sensing Unit.

The structure of the film is built around a nested selection of Phaeleh’s last three albums; Lost Time, Illusion of the Tale & Somnus. The tone & pacing of each track influenced the choice of material used.

Typically each time lapse sequence was photographed at 1 frame per second.

Each sequence was processed in Photoshop. A dirtmap was made in order to repair dust, blemishes and hot pixel artifacts that would otherwise confuse the re-timing phase of the workflow resulting in strobes and distracting blurs.

Image processing techniques were used to emphasize features on the Earth’s surface. Every sequence consists of a number of layers that when masked, processed & blended correctly produce the final look of each shot.

To make sure each sequence was recreated faithfully to the actual rate of speed observed I referenced time-stamps on the first and last frame in the sequence and used frame interpolation software to produce the other 59 frames.

The length of the film is exactly the length of time it takes ISS to orbit the Earth once, 92 minutes & 39 seconds.

56 Comments

  1. Posted February 9, 2018 at 3:34 pm | Permalink

    “riverrun, past Eve and Adams, from swerve of shore to bend of bay, brings us by a commodius vicus of recirculation back to Howth Castle and Environs.”

    /@

    • Posted February 9, 2018 at 3:40 pm | Permalink

      Btw, if you like the music, it’s available on bandcamp. (Which is great way to support musicians, cf. iTunes, Google, Amazon, &c.; bc takes only the money from every 11th sale.)

      It’s definitely going on my wishlist!

      /@

    • Posted February 9, 2018 at 3:42 pm | Permalink

      … that it’s at the beginning?

      Is the significance that you’re looking for something different than … 

      /@

  2. phoffman56
    Posted February 9, 2018 at 4:12 pm | Permalink

    “…it took about ninety minutes per orbit. Apparently that’s still the case…”

    Yes, IIRC (at that distance from the centre of mass of the earth) Newton explained to us centuries ago that everything orbits at that same speed, and much more generally of course. And (despite Smolin’s recent philosophizing) laws of physics tend to not evolve in time. I think it would be centuries before General Relativistic corrections would make any noticeable difference, but somebody might have done that calculation.

    Closer in would be faster, except that the thin air gets thick enough to bring the satellite down. And farther out is slower. E.g. stationary orbits to send us our satellite TV. These take about 24 hours and run parallel to the equator, if I understand correctly.

    • Posted February 9, 2018 at 4:21 pm | Permalink

      Does a geostationary satellite ever actually circle the Earth?

      (How is the period of an orbit canonically measured: With respect to the stars, the Sun or a fixed point on the Earth’s surface?)

      /@

      • glen1davidson
        Posted February 9, 2018 at 4:39 pm | Permalink

        Does a geostationary satellite ever actually circle the Earth?

        Yes.

        Rotation under it makes no difference. It just has to move around the particular body.

        It just doesn’t move with respect to a points on the surface of the earth. But those points also are moving around the center of the earth, so the satellite and surface points remain in synch while both circle the center of the earth.

        For a small satellite, you’re approximately going around the center of the earth. For something like the moon-earth system, both orbit a point within the earth that is offset from the earth’s center toward the moon.

        Glen Davidson

        • gravelinspector-Aidan
          Posted February 9, 2018 at 7:17 pm | Permalink

          For a small satellite, you’re approximately going around the center of the earth. For something like the moon-earth system, both orbit a point within the earth that is offset from the earth’s center toward the moon.

          Many people mis-estimate the relative masses of Earth and Moon. While the Moon is approximately 1/4 the diameter(radius) of the Earth (3474.2 vs 12742 km ; 1:3.67, but that equates to a 1:49 ratio of volumes. Since the Moon is less dense than the Earth (smaller iron core, considerably less pressure compression of the interior ; 3340 vs 5514 kg/m^3), the ratio of masses is even larger, 1:82. The Moon is approximately 1% of the Earth’s mass. Most people think it’s much closer to the ratio of diameters, neglecting the other factors.
          From the ratio of the masses, you can get the ratio of distances between the centres of the two bodies and their mutual barycentre – the centre of mass of the Earth- Moon system. With the Moon’s typical orbital range being 384000km, the mass ratio puts the distance from Earth’s centre to the barycentre as 4700km – which is in the Earth’s lower mantle.
          Doing the same calculations for Jupiter puts the Jupiter-Sun barycentre a little over half way from the centre of the Sun to it’s surface. to a first approximation, the rest of the planets don’t matter – including Pluto and Planet Nine (Brown-Batygin, 2016)

          • rickflick
            Posted February 9, 2018 at 7:25 pm | Permalink

            “The Moon is approximately 1% of the Earth’s mass.”

            Holy cow jumped over the moon! That’s just amazing. And yet it manages to lift the oceans a few feet.

            • gravelinspector-Aidan
              Posted February 9, 2018 at 9:11 pm | Permalink

              Like I said, most people carry the wrong impression. I suspect it’s the cubing of the diameter that catches people. It caught me when I first worked it out too.
              All of a sudden, the “Giant Impact hypothesis” for the formation of the Moon doesn’t sound so incredible, does it?

              • rickflick
                Posted February 9, 2018 at 10:01 pm | Permalink

                That’s right too. The impact of a Mars sized object would have no trouble lifting 1% of the Earth into orbit. I imagine some of the other planets(Phobos and Demos around Mars?) experienced this as well. Small moons can be considered impact splatter.

              • gravelinspector-Aidan
                Posted February 10, 2018 at 5:16 pm | Permalink

                Phobos and Deimos may be accumulated “splatter” from impact debris, but they’re also perilously close to the Roche Limit (the point at which the differential forces due to gravitational gradient can overcome the self-gravity of a satellite, leaving only the tensile strength of the satellite material to hold a satellite together – or to assemble it from parts. Most people are assuming that they’re captured asteroids, but that’s not without problems either.
                One of the Ice Giant’s satellites – I forget if it’s one of Uranus’s or Neptune’s swarms – was imaged by Voyager and seen to have a wild hodge-podge of terrain types, which some have interpreted as signs of a “cold” reassembly from something fragmented in an earlier collision.
                It’s a violent place, space.

              • glen1davidson
                Posted February 9, 2018 at 10:23 pm | Permalink

                I imagine some of the other planets(Phobos and Demos around Mars?) experienced this as well. Small moons can be considered impact splatter.

                They’re believed to be captured asteroids. Most small moons, like the non-Galilean moons around Jupiter and non-Titan moons around Saturn are thought to be, usually a half of binary, mutually orbiting asteroids.

                Glen Davidson

              • gravelinspector-Aidan
                Posted February 10, 2018 at 5:23 pm | Permalink

                That’s certainly the leading hypothesis for the formation of Phobos and Deimos. But the question remains of how come their orbits are very circular. Most models of capture events produce satellites in high eccentricity orbits, and the tidal forces to circularise them take time to operate. More time than is available *with* the same components in Martian space as at the moment. More debris – a ring, even? – in the past might have circularised the orbits faster, and then … ? Well, an icy ring (as Saturn) could then evaporate as the Faint Young Sun paradox works it’s climatological ju-ju. Not insoluble, but definitely not “solved”.

              • rickflick
                Posted February 9, 2018 at 11:01 pm | Permalink

                Hmmm…that would make our moon kind of special. It’s hard to know, but maybe life would not have gotten started on Earth if it wasn’t for heave-ho of the tides. Much of life in the oceans is synchronized to the lunar cycles.

              • gravelinspector-Aidan
                Posted February 10, 2018 at 5:26 pm | Permalink

                That’s a not unreasonable position. However at least one major model for abiogenesis does not require tidal action.
                On the third hand, the alternation of environments due to twice-daily inundation and drying is almost tailor-made for driving evolution of changed body forms and chemistry.

              • Michael Fisher
                Posted February 10, 2018 at 5:56 pm | Permalink

                And of course all that groovy tidal action keeps a number of ice moons in a nicely liquid-but-maybe-rather-salty-world-ocean state. I often wonder if 99.9% of complex, thinking organic life is trapped under ice – no tech as we know it & probably no knowledge of a universe ‘above’ their ice ceiling.

              • glen1davidson
                Posted February 10, 2018 at 12:16 am | Permalink

                Yes, it’s quite special, notably because it’s large compared with the planet (much smaller than earth, of course, but still relatively large for the planet compared with other planets’ moons). That means that it keeps the tilt of earth’s axis the same over billions of years, which gives life relatively stable climates to which life can adapt.

                Mars has about the same axial tilt as earth right now, but it’s thought that over the history of the solar system that there have been dramatic shifts in the tilt of Mars. When there was little tilt there’d be no real seasons, so no summer in what would be “temperate zones” on earth, and it would be worse when one pole is warm all summer (with no night), then cold all winter (with no day), with the rest of Mars just staying chilly.

                Earth, by contrast, keeps the same tilt and same seasons through time, thanks to a relatively large moon.

                Glen Davidson

              • gravelinspector-Aidan
                Posted February 10, 2018 at 6:01 pm | Permalink

                Yeah. I know that proposition. But even Mars barely reaches a 1deg axial inclination change per million years. Putting that into a terrestrial context, it would mean that climate zones would have shifted by around 37km since the origin (well, oldest fossils) of Homo Sapiens. Climates change far faster than that, so the contribution from axial tilt shifting to evolutionary pressures is not major.

              • Posted February 10, 2018 at 7:30 am | Permalink

                Rickflick:

                Hmmm…that would make our moon kind of special. It’s hard to know, but maybe life would not have gotten started on Earth if it wasn’t for heave-ho of the tides. Much of life in the oceans is synchronized to the lunar cycles.

                Read Asimov’s The Triumph of the Moon.

              • Posted February 12, 2018 at 11:45 am | Permalink

                Cube-square-linear relationships are hard – look how long it took (until the time of Galileo, and if I recall, he still doesn’t quite get it right) to get something as “simple” as the various proportions of bones in animals.

            • nicky
              Posted February 10, 2018 at 1:23 am | Permalink

              It also explains why the ‘tide-cycle’ takes about 12 hours instead of 24h. As a younster I never understood that, until I found out that the barycentre of the Earth-Moon system is well below the earths surface.

            • Posted February 10, 2018 at 2:04 pm | Permalink

              The oceans account for only 0.02% of Earth’s total mass.

              /@

              • rickflick
                Posted February 10, 2018 at 4:25 pm | Permalink

                Like tight leotards, I know.

              • Posted February 10, 2018 at 6:53 pm | Permalink

                Nice image!

                /@

          • Michael Fisher
            Posted February 10, 2018 at 9:05 am | Permalink

            Hi nicky – you wrote:

            It also explains why the ‘tide-cycle’ takes about 12 hours instead of 24h. As a youngster I never understood that, until I found out that the barycentre of the Earth-Moon system is well below the earths surface./blockquote> This is incorrect – the barycentre is irrelevant What matters is the difference in gravitational ‘force’ across a body – that is the tidal force.

            [1] If you replaced the Moon with an object the mass of the Earth the barycentre would be in outer space – and yet you would still get a tidal bulge on the Earth side facing the more massive Moon AND on the Earth side facing away from the more massive Moon. The Moon of course also has two tidal bulges caused by the Earth [irrespective of the mass of the Moon]

            [2] As it is now [with standard Moon] there is a second pair of tidal bulges on the Earth caused by the Sun’s gravity even though the barycentre of the Earth-Sun is inside the Sun! The Sun’s tidal effect on the Earth is about half that of the Moon.

            [3] In general all the masses in the universe have a tidal influence on all the other masses [forget ‘inside’ black holes & across small objects!] – so Pluto raises a tide on the front & back of the Sun which is below the level of noise. From an Earth perspective the only tides that matter are those caused by the Moon & the Sun – even Jupiter & Saturn have little influence on the tides on Earth.

            • Michael Fisher
              Posted February 10, 2018 at 9:07 am | Permalink

              I screwed up – my quote of you is 4 lines & the rest is me 🙂

            • gravelinspector-Aidan
              Posted February 10, 2018 at 6:06 pm | Permalink

              Not untrue. But Jupiter is still the dominant body in pushing the Earth’s orbit around with respect to the Sun. If there were no Jupiter interaction, for example, there would be zero chance of Mercury or the Earth being ejected from the solar system, whereas with Jupiter the odds are on the order of 1% (before the Sun goes red giant).

              • Michael Fisher
                Posted February 10, 2018 at 6:28 pm | Permalink

                I realise you wrote “not untrue”, but in my comment to nicky I was only talking about tidal forces & they follow an inverse CUBED law. From a tidal perspective the max tidal influence on Earth of…

                Sol = 45% of the Moon’s tide
                Venus = 0.005% of the Moon’s tide
                Jupiter = 0.002% of the Moon’s tide

                Moon + Sol account for more than 99.99% of the tidal influence on Earth

      • Dick Veldkamp
        Posted February 9, 2018 at 4:46 pm | Permalink

        Of course it just depends on the coordinate system you choose.

        However, considering that there is nothing special about the geostationary orbit (it is just an orbit with a period of ~24h, and a radius of 42000 km or so), I would say that a geostationary satellite does “circle” the Earth.

        For any orbit of this type outside the equatorial plane we would not hesitate to use the word “circle”.

      • phoffman56
        Posted February 9, 2018 at 5:35 pm | Permalink

        Instead of picturing the earth, imagine it shrunk right down to its centre of mass. But keep all the mass, since orbits do depend on the earth’s mass, but are independent of the mass of the satellite (as I’d said). Anyway, now there’s no ‘earth’ motion (we ‘coordinate’ with that mass centre fixed as the origin). There’s no rotation, since points don’t rotate. Then the (so-called stationary) satellite goes nicely round that point every 24 hours. So it does revolve around the earth.

        The farther out you get, the longer each orbit takes. So if you could spy a satellite which was, say, twice as far out as the correct orbit for stationary, it would appear to you to be going in the opposite direction to what it’s actually going. Same thing as driving past a cyclist on your own side of the road, if you avoid looking at anything fixed to the ground. Standing right next to another train in a nice smooth Euro rail station, when the other train seems to start moving, sometimes it’s you that’s actually moving in the other direction. Or else the other way round.

      • Posted February 9, 2018 at 5:45 pm | Permalink

        Hmm … I don’t really need the didactic responses. I understand celestial mechanics well enough. I was imagining how Wittgenstein might have responded. Certainly, from the pov or an observer on a non-point Earth, a geostationary satellite wouldn’t look like it circled anything.

        And it seems to me that there is some utility in measuring the orbital period with respect to a fixed point on Earth, to know when a (non-geostationary) satellite would next be overhead.

        /@

        • phoffman56
          Posted February 9, 2018 at 7:06 pm | Permalink

          “..imagining how Wittgenstein might have responded..”

          Here’s a supposed Wittgenstein quote, placed with a quote from Everett’s thesis, at the very beginning of David Wallace’s excellent “The Emergent Universe” on the many worlds interpretation of quantum theory. I think Wallace is being sarcastic putting it there, but many philosophers will say I’m just too much of a dullard to appreciate the other Ludwig’s depth:

          “What would it have looked like if it had looked like the Earth went round the Sun?”

          • phoffman56
            Posted February 9, 2018 at 7:08 pm | Permalink

            Sorry, “The Emergent Multiverse”

      • gravelinspector-Aidan
        Posted February 9, 2018 at 7:21 pm | Permalink

        (How is the period of an orbit canonically measured: With respect to the stars, the Sun or a fixed point on the Earth’s surface?)

        Yes. Both, and probably several others too. There would be a period for it to return to the same position with respect to the “fixed” stars as seen from far away. Another period for it to appear in the same position as seen from the centre of the Earth. Another (because of non-trivial parallax effects) from one position on the Earth’s surface.
        And I can’t remember the names of the different periods.

  3. Posted February 9, 2018 at 4:48 pm | Permalink

    You can also watch a live view from the ISS here!

  4. rickflick
    Posted February 9, 2018 at 5:38 pm | Permalink

    I’ve just watched few minutes so far but the earth looks like it could be some uninhabited exoplanet. So far I can’t identify any familiar geography. Clearly, there are rivers and larger bodies of liquid and ripples of dunes admitting to a windy atmosphere. But, so far it could be planet XYZ a few hundred light years away. I’ll keep watching for something that tells me there are conscious, moderately intelligent(qualification due to the possibility they could have elected a Trump of their own) beings down there.

    • rickflick
      Posted February 9, 2018 at 5:44 pm | Permalink

      At about 8:30 I can identify the Nile River. Looking for the Aswan Dam as evidence of life on this planet. It must be just out of frame.

    • glen1davidson
      Posted February 9, 2018 at 5:47 pm | Permalink

      Red sea (and Nile delta) starting around 8:20. But north is down, not up;

      Glen Davidson

      • gravelinspector-Aidan
        Posted February 9, 2018 at 7:30 pm | Permalink

        But north is down, not up;

        I’ve noticed that with lots of images posted from the ISS too. It is another hurdle to identifying the subjects of their photos. I haven’t worked it out exactly, but I suspect the the actual angle between image-up and north is the orbital inclination (51.64deg), suspecting that has some relation to the orientation of solar panels and radiators to the Sun. Plus-or-minus the Earth’s axial tilt at different times of the year. Multiplied by Cook’s Constant.

    • rickflick
      Posted February 9, 2018 at 5:50 pm | Permalink

      23 minutes in and there we have evidence of life. It’s city lights at night. Gotta have a night life if you’re a conscious being.

    • rickflick
      Posted February 9, 2018 at 6:37 pm | Permalink

      At 1:15:38 I see Baja California, Mexico.

    • rickflick
      Posted February 9, 2018 at 6:40 pm | Permalink

      There’s a thin East-West line that I suppose could be the beginnings of Trump’s immigration policy.

    • rickflick
      Posted February 9, 2018 at 6:41 pm | Permalink

      Overall a spectacular tour.

    • gravelinspector-Aidan
      Posted February 9, 2018 at 7:36 pm | Permalink

      They did that experiment with, IIRC, the Galileo spacecraft during one of it’s gravity assists around Earth. The clearest evidence of life they could find was the “red cut-off” as an indication of some common chemical actively seeking out and absorbing the highest-intensity wave band of the solar radiation.
      Don’t confuse Star Trek’s “scanners” with reality. “M-class planet” indeed. I’m almost tempted to find out if Trek-ology has actually invented a word salad to go behind that phrase.

      • gravelinspector-Aidan
        Posted February 9, 2018 at 7:40 pm | Permalink

        word salad
        My brain feels … used. Not in a good way.

  5. Jake Sevins
    Posted February 9, 2018 at 6:57 pm | Permalink

    I have this playing in the background in my living room now… the music is a little spooky in parts, but still soothing.

  6. gravelinspector-Aidan
    Posted February 9, 2018 at 9:08 pm | Permalink

    Beautiful orographic control of cloud formation around 07:00 ; I haven’t worked it out, but I suspect this is maybe the Hoggar. Yeah, that would gel with Rick & Glen’s timings up-thread. Odd mountains, the Hoggar.
    … Ah, it flips from a NE orbit pass to a SE path when it jumps from the Sahara to the Nile valley/ Red Sea. And more orographic cloud over the West Arabian mountains, shrouding Mecca from infidel eyes. nice dendritic drainage (relicts from the Pleistocene) snaking out of the Mountains into the Empty Quarter. Then at 15:00 the Yemen and Somaliland coasts. (There are proposals for oil exploration in Somaliland, which is definitely not Somalia. Still made my ring twitch as I touted for the work.)
    The city at 23:00 is a discontinuity. They’ve jumped back to the Red Sea coast, on a NNE track. So you see Mecca-Medina, then Ryadh and then L-to-R Basra-Dahrahn-Qatar-UAE and the Iranian coast. I can’t quite make out the Caspian, so they do the next jump from somewhere near the Kazakh-Iranian-Afghan border. Then more seascape. Landfall again is
    [Discontinuity] At 38:43, we’re back over the Red Sea coast, a little north of Medina heading NE to pass over Baghdad and you can just see the end of the Gulf at RHS. At 43:00 you can see the Caspian. Everything gets lost in cloud then. At 59:40, I think I see the Korean coast with the East Sea (Sea of Japan), then Kamchatka? Then two passes (on to SE, then one to NE) over the Baja California as someone else spotted.
    It looks to me as if the compositor has stitched together various clips in more-or-less the right order, but left out the boring bits of acres of ocean. I’ll assume that he’s got his timing right, but it’s not what I’d expected from the puff.

    • rickflick
      Posted February 9, 2018 at 9:54 pm | Permalink

      You deserve a prize for naming all those places. At first I was expecting a single, actual orbit, but that would be too boring – I understand. So the film zigzags. And why so much of the Middle East? Maybe less clouds.

      • gravelinspector-Aidan
        Posted February 10, 2018 at 4:57 pm | Permalink

        Cloud cover was my thought as I asked myself the same question.

        • Michael Fisher
          Posted February 10, 2018 at 5:46 pm | Permalink

          INO the guy who put this time lapse together, Seán Doran was going for an ‘orchestrated’ mood piece that matched the imagery to various Phaeleh [AKA Matt Preston of Bristol, UK] vinyl LP tracks & ending with the Aurora Borealis finale. He writes this:

          “The tone & pacing of each [music] track influenced the choice of [video] material used”

          I was hoping for night time lightning strikes under cloud, but he didn’t have that material to hand I guess.

          • gravelinspector-Aidan
            Posted February 10, 2018 at 6:08 pm | Permalink

            I turned the sound off after about 5 seconds.

    • nicky
      Posted February 10, 2018 at 4:50 am | Permalink

      Yes I saw about the same. About all of the first half was Red Sea, Egypt, Horn of Africa, and further Middle East. Notable how narrow the Gate of Tears indeed is.
      Then some persian Gulf, Iraq, Iran and Caspian sea. Could not orient myself well in what I guess was Central Asia, lots of mountains and cloudy.
      The image flipped regularly. And I suspect some North East Asian passage, guessed I saw Sakhaline. Lower California was again very clear (and Mexico), like the red Sea earlier. And then again what I suspect was the Gulf of Mexico, but not sure.
      I found it exhilarating, but at the same time slightly disappointing with the flipping and the cloud cover.

      • gravelinspector-Aidan
        Posted February 10, 2018 at 6:02 pm | Permalink

        I was arguing with myself over Sakhalin Island, or Kamchatka. Couldn’t decide, and by that point, wasn’t caring much.

  7. Posted February 10, 2018 at 10:23 am | Permalink

    Earth looks great from ISS. Wish we could work and play this way all the time in peace.


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