Time lapse: The spinning Chilean sky

By Phil Plait | February 21, 2011 7:10 am

I do so love time-lapse animations, and this one is particularly nice: it shows four of the ALMA microwave antennas in Chile as they scan the night sky, while the starry vault rotates around them. [Make sure you set the resolution to 720 and make this full screen; it’s really nice.]

The video starts at moonset, and ends with an amazing view of the the vast central bulge and disk of the Milky Way looming over the ‘scopes.You can see the famous Coal Sack dark dust cloud as a circular "hole" in the Milky Way, with Crux, the Southern Cross, right next to it. Just above and to the right (at the lower tip of the elongated dark patch in the Milky Way) is the bright star Alpha Centauri, with Beta Centauri just below it. The European Southern Observatory has posted a similar video showing a different part of the sky, too. These videos are from last summer, but there’s a timeless, enthralling quality to them.

I found this through the tortuous route of a tweet from my friend Lila Mae, then to io9 (who got it from reddit), and then to the ESO. Phew!

Credit: ESO/José Francisco Salgado

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (37)

  1. These videos are from last summer

    Wouldn’t that be winter for them? 😀

  2. If you concentrate near the horizon, you really get the feeling of the Earth spinning! Feeling a bit dizzy now …

  3. Absolutely amazing time lapse! The fact that you can clearly (as far as clearly goes in this instance) see the central bulge is awesome!

    One question. At 35 seconds there is a very strange white object that flashes (slowly, considering) across the middle of the time-lapse (slightly to the right). Anyone know what that is likely to be? Only lasts for a second on the video.

    Potential UFO alert!! 😉

  4. Gorgeous, but I can’t actually identify any of the objects you point out because I don’t know what point in the video you are referring to, so left, right, up and down don’t mean much as the whole sky turns upside down. I’m familiar with the Southern Cross, and know how to find Alpha Centauri from it, but this video shows … too many stars!

  5. So watching this has made me wonder whether our orbit around Sol is aligned with the galactic plane, so to speak. Do we orbit “flatly” along with the arms of the Milky Way or are we at an angle? I haven’t done enough observation to derive the answer myself, so perhaps one of the astronomers here can shed some light on the subject.

  6. Moogle

    Gah! Full screened on a large monitor, sitting back, it really looked to me like the stars were moving relative to each other, consistently enough that I had an illusion of depth. Playing it again while closer to the screen, I think it was just the compression artifacts. But still it was a really neat effect.

  7. Aaron

    @Alex: It is probably a meteor . . . or an alien spaceship . . . or perhaps even a -government- spaceship! Whatever it is, it happens to fly right through both the Trifid and Lagoon nebulae, which is pretty awesome!

    @Bill: The plane of the ecliptic (the plane which contains the mean orbit of Earth) and the galactic plane of the Milky Way are inclined by about sixty degrees. Where they identical, then the Sun and the planets would always appear somewhere within the band of the Milky Way, as seen within our sky. Well, approximately–not all of the planets orbit in the same plane as Earth. In fact, the invariable plane of the solar system–defined by the average of the planets’ orbital angular momentum and thus dominated by Jupiter–differs from our orbital plane by about 1.5°.

  8. CameronSS

    @Alex Hall: From the video author on YouTube: “@iampivot – considering it’s right before sunrise, my guess is that it’s either the International Space Station or more likely an iridium flare — a temporary sharp increase in brightness of the GPS satellites due to their solar panels catching the light of the sun. Iridium flares, which are often more brilliant than the planet Venus, can be seen worldwide… appearance predictions are published well in advance through multiple websites and phone apps (Heavens Above, for example).”

    Also, did anyone else, every time they all suddenly slewed at the same time, think “OMG wassat?!”

  9. Gary Ansorge

    Umm, pretty,,,and a bit disorienting.

    Gary 7

  10. dave cortesi

    at 0:30 the dishes have a little hissy-fit, shaking their heads rapidly. What’s that all about? In fact they seem to point all sorts of directions throughout the night. Why don’t they schedule observing targets to get a smoother and simpler progression point-to-point, rather than jerking back and forth all the time?

  11. Lila

    Aww. I feel so honored. It is so much fun to watch, isn’t it?

  12. José Francisco Salgado (creator of the video) works at the Adler Planetarium in Chicago. Our astronomy club had the pleasure of having him as a guest speaker last fall, he’s a great guy, very enthusiastic. He takes beautiful photographs and timelapses of observatories around the world, much of which he turns into audio/visual presentations for the planetarium. I’d recommend checking out his Flickr for more: http://www.flickr.com/photos/josefranciscosalgado/

  13. @dave cortesi: My understanding is that very large radio telescopes do not have equatorial tracking like many optical telescopes, meaning they do not track a single object in the sky as the earth rotates. Since they are on an alt-az mount, they point to a fixed spot in the sky and let whatever object they want to observe transit in front of the dish’s field of view. They then take their data in the few minutes or seconds as the object passes. I’m not sure this explains the hissy-fit at 0:30 (perhaps this was a calibration sequence?) but it might help explain why they jump around a lot throughout the video.

  14. Pete Jackson

    @1 Larian: Yes, you’re right, it must be the northern hemisphere summer, which means winter in Chile. The clue is that Sagittarius (the direction of the center of our Galaxy) is in opposition to the sun. The sun goes through Sagittarius in December, and is in opposition to it in June.

    Winter, of course, means long nights and longer time-lapse sequences like this one!

  15. Russell

    I had a tummy ache before, and now it feels better ! Beautiful.

  16. The Fermat Liar

    @ Garrett: yeah, I always squint my eyes a bit and focus on one spot when I look at these time lapse night sky videos – you can really get a sense of the bigness of the earth and the way it moves through space. I’d love to see an Imax sequence of something like that, although it might make you kind of dizzy.

    Incidentally another way to get a feel of the size of the earth is to lie on your back and look at some very high clouds, so that the blue sky fills your entire field of vision, and imagine that you are looking downwards rather than upwards (say, into the Pacific, as you obviously won’t see any landmasses this way…) you can vaguely get a feel of how the earth looks from the edge of space, and a (slightly) better appreciation of its size.

  17. George Martin

    kurtjmac @14 said:

    @dave cortesi: My understanding is that very large radio telescopes do not have equatorial tracking like many optical telescopes, meaning they do not track a single object in the sky as the earth rotates.

    While they are not equatorial mounted, alt/azimuth telescopes DO track celestial sources
    at the sidereal rate by driving both axes of the telescope. By the way, it not just modern radio telescopes which are alt/azimuth mounted but also all modern large optical telescopes. It is much easier and therefore less expensive to build them that way.

    The only thing an alt/azimuth telescope can’t do, compared to an equatorial mounted telescope, is to track an object near the telescope’s zenith. But that is a small price to pay for a simpler and less expensive mounting.

    The largest telescope ever built with an equatorial mount is the NRAO’s 140 foot telescope at Green Bank, West Virginia. I’ve heard that the reason it is equatorial mounted rather than alt/az is that when it was being designed in the 5o’s, it was thought computers of the time, that they could afford, were not fast enough to do the calculations necessary to command the motors on both axes.


  18. George Martin

    @dave cortesi

    They have not yet started doing science with ALMA, only testing as new antennas get moved to the high site. (I think there are several more antennas there now than the four in the video.) But even if what was seen were an astronomical science observation, the telescopes would normally often move off the object of interest to observe a calibrator source; even for test observations. (And besides, there may be more than one object of interest in a run.) That is likely the reason the individual dishes appear to be jumping around in the time lapse domain.

    In 2011 ALMA expects to begin the transition from construction to operations. A call for “Early Science Proposals” is expected any day now:

    The Joint ALMA Observatory (JAO) expects to start Early Science observations (Cycle 0) on a best effort basis late in 2011 and a call for proposals will be issued at the end of the first quarter of 2011.

    See: http://www.almaobservatory.org/en/announcements-events/250-plan-for-alma-early-science-cycle-0


  19. Salt

    Thank you, Bad Astronomers, for presenting that soothing swirl of sky. Since the days of my childhood when I was glued to a seat at the old McDonnell Planetarium (whenever I had the price), I’ve always found space imagery enthralling and becalming at the same time.

    News and events in my part of the world have been awful–seeing the galaxy spin (I’ve not slept under the stars in decades) puts all kinds of folly in perspective.


  20. Pete Jackson

    @18 George: They had a better idea for the Parkes 210-foot and Algonquin 150-foot radio telescopes. They have altazimuth mounts, but deep inside, there is a small equatorial mount (called the “master equatorial”) that goes to the commanded right ascension and declination, and the altitude and azimuth are read off of it, and the main telescope commanded to that altitude and azimuth. Basically an analog computer if you will!

  21. @ Alex @ Aaron:

    At about :30-:31 there’s a huge lens flare from a vehicle driving by with its lights on. At about :31-:32 there’s a flash of light reflected on the far right dish. Are those what you were referring to?

  22. Aaron

    @ kuhnigget: I see those, but this is far more subtle. Look at the galactic center in full screen at 720p. At 0:35 a white light appears just off to the right.

    Considering the fact that this is a time lapse video, it is far too long lived to be a meteor as I suggested earlier. Instead, I agree that it is probably either the ISS or an Iridium flare (which, are reflections off of Iridium Communications Inc. satellites, not GPS, and therefore neither an alien nor a government spacecraft, but rather a private one).

  23. Daniel J. Andrews

    A bit OT, but is about satellites. A handy app for iPod touch, iPhone, iPad is NASA’s app. One of the functions is that it lists visible satellites/space station transits for your area. Tonight it said the ISS would go overhead at 7:10, and it was right on schedule. I had my dad, my wife, and my dad’s next door neighbours outside waiting for it despite the cold. Everyone was excited and I’ve given them the times for the next few transits for this week.

    The app is becoming one of my favourite apps and it does a whole lot more than just satellite transits. Search terms: NASA, app.

  24. @ Aaron:

    Ah, yes, I see what you were talking about.

    Yeah, looks like a satellite in a polar orbit. (Judging by its roughly S to N path) I suppose if you could get the date and time the video was shot it would be easy enough to figure out the exact satellite.

  25. Messier Tidy Upper

    Great clip. Love it. :-)

    What a difference in darkness the Moonset makes.

  26. Joseph G

    @5 Bill DeVoe: The invariable plane of the solar system (sort of a weighted average of the inclination of all the planets’ solar orbits, I believe that’s what you’re referring to) doesn’t seem to be at all aligned with the galactic plane. The rotation of protoplanetary discs from which planets form is influenced by the local density and velocity of the dust clouds from which they collapse, so the orientations of the various star systems in the galaxy are pretty much random.

    On a related note, our orbit around the galactic center is also inclined to the galactic plane, so that at times we’re closer to one “side” or the other, though IIRC this inclination is extremely low.

  27. Joseph G

    Neat! 8)
    What’s with the cars that come and go at intervals? Or is that just one car that’s blurred and brightened by the time-lapse?

  28. @dave cortesi et al.
    Calibration is most likely correct. The way we calibrate our data with these dishes is to find a source with a very well known brightness, something we call a “Standard Candle”. By measuring the flux of these standard candles and comparing it to a patch of black sky that is very close to it, we can find out the brightness temperature of the telescope system and determine the true flux values of whatever sources we might want to observe next. Most often we will take two “off-source” measurements for each “on-source”, one each side of the standard candle, which gives it that strange “skitzing out” effect.

  29. @7 Aaron and @27 Joseph G. Thanks! That’s what I’d suspected, but it wasn’t one of those things I could affirmatively declare one way or t’other. Aaron’s explanation that the planets would appear within the Milky Way’s band made it easier for me to explain to my daughter. :) Appreciate it!

  30. Keith Bowden

    I love this stuff!

    I had a great couple of conversations with my 7 year old nephew over the weekend. We were outside and I pointed out Jupiter and Sirius. (Pretty much all we could see that night from my home. :( ) He was fascinated and wants to get a telescope so we can look at the stars through it together. He was amazed that one “star” was a planet.

    The next day I took out an oversized coffee table book (at a yard tall, it practically is a coffee table!) and showed him pictures of the sun and planets, showing him more about Jupiter and that men have been on the moon, looking back at Earth.

    I also showed him the solar system extra on the 4th disc of From the Earth to the Moon. It made a good break from Spongebob and jumping on my bed… 😀

  31. Joseph G

    @#7 Aaron: D’oh! Sorry, I didn’t even see your post way up there! I’m a doofus 😛

  32. Chris Winter

    Another awesome time-lapse video. It’s (mildly) interesting that the abbreviation for European Southern Observatory (ESO) means something in Spanish, so that the title of this video means “that soul.”

    And one great thing about radio astronomy observatories is that you can drive cars around them at night without causing problems. (Unless your car has a leaky ignition wire, or you key the transmitter you installed.)

  33. Vaish

    That was stunning! Makes me want to sit next to those antennas, stare up at the sky and watch the dawn break.. hmmm


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