APOD: Earth Rotating Under VLT (2011 Jun 01)

[APOD Robot]

Earth Rotating Under Very Large Telescopes

Explanation: Why is the Earth moving in the above video? Most time lapse videos of the night sky show the stars and sky moving above a steady Earth. Here, however, the frames have been digitally rotated so that it is the stars that stay (approximately) steady, and the Earth that moves beneath them. The video dramatically shows the actual rotation of the Earth, called diurnal motion, in a clear and moving way, as if the camera were floating free in space. The telescopes featured in the video are the Very Large Telescopes (VLT) in Chile, a group of four of the largest optical telescopes deployed anywhere in the world. A discerning observer of the above time lapse movie may also note the use of laser guide stars, zodiacal light, the Large and Small Magellanic Clouds, and fast-moving, sunlight-reflecting, Earth-orbiting satellites. The original video, on which the above sequences are based, can be found here.

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[islader2]

The music is as bad as it can be. Mute it, mute it!

[Ann]

Nice video. I like the music, too.

Ann

[Beyond]

Well, that was a bit different. Almost but not quite like defying gravity. I would have liked to have seen a bit more earth rotation, or even a complete 360' rotation, but i guess that isn't possible?

[Alberto Fernandez]

Made me quite dizzy, but even so, I loved it! A very nice idea, thanks for showing it to all of us!

[owlice]

I'm with Ann: like the video, like the music.

Very cool!

[Indigo_Sunrise]

WOW! Talk about a nearly vertigo-inducing video! I enjoyed it immensely! Especially at the end where the VLT complex is seen from a bit of a distance and the mountains seem to sort of crawl up and off to the right. Very interesting perspective!
And I thought the music was fitting, also.

Overall a 9 out of 10 - mostly for originality!

[Redbone]

It took me a while to translate the sweeping, rotating motion of the horizon into the rotation of a sphere. I learned to picture the center of rotation, off of the screen, and that helped. Sometimes the motion, or horizon, rotated left, as if you were in a plane doing a steep turn to the right. Sometimes the horizon rotated right, and once or twice it remained horizontal and appeared to be coming at the screen or going away from the screen. I interpreted that as Northern and Southern hemispheres, and equatorial. I feel that the presentation could be improved by making an effort to use the different hemispherical motions more harmoniously to give the viewer a sense of where on the earth the scene is located, rather than randomly jumping around. And yes, the music was not my choice. But overall very unique and interesting.

[biddie67]

Very interesting perspective!

[neufer]

I'm with Ann: like the video, like the music.

VERy cool!

Music: Arcadia (Licence: Kevin Macleod)

<<Arcadia is a 1993 play by Tom Stoppard concerning the relationship between past and present and between order and disorder and the certainty of knowledge. It has been cited by many critics as the finest play from one of the most significant contemporary playwrights in English. In Arcadia, Stoppard presents his audience with several highly complicated mathematical and scientific concepts. Stoppard uses these theories and ideas within the play to illuminate relationships between characters. One of the main thematic concepts in the show is chaos theory.

• "Chaos mathematics is about the recovery of information from apparently chaotic and random systems where entropy is high… It is 'asymmetric' (unlike the equations of classical physics), yet it finds regularities that prove to be the regularities of nature itself. Strikingly, this mathematics can generate patterns of amazing complexity, but it also has the power to generate seemingly natural or organic shapes that defeat Newtonian geometry. The promise, then, (however questionable it is in reality) is that information, and by extension, nature itself, can overcome the tendency to increase in entropy." -Paul Edwards
  
  "Deterministic chaos deals with systems of unpredictable determinism, but the uncertainty does not result in pure randomness but rather in complex patterns. Traditionally, scientists expected dynamic systems to settle into stable, predictable behavior. However, deterministic chaos has shown that as many of these systems respond to variations in input… Surprisingly, within these random states, windows of order reappear… 'There is order in chaos—an unpredictable order, but a determined order nonetheless, and not merely random behavior.'" -John Fleming

Further scientific and mathematical concepts coVERED in Arcadia are the second law of thermodynamics, and in relation to it, entropy. Fleming describes these two principles. "Entropy is the measure of the randomness or disorder of a system. The law of increase of entropy states that as a whole the universe is evolving from order to disorder. This relates to the Second Law of Thermodynamics, which states that heat can flow in only one direction, from hotter to colder. Since these equations, unlike Newton's laws of motion, do not go backward and forward, there is an 'arrow of time' that points toward the eventual 'heat death' of the universe."

By using all of these concepts within Arcadia, Stoppard exposes how "there is an underlying order to seemingly random events." The characters in the play discuss these topics while their interactions reflect them.

Arcadia is set in Sidley Park, an English country house, in both the years 1809–1812 and the present day—1993 in the original production. The activities of two modern scholars and the house's current residents are juxtaposed with the lives of those who lived there 180 years earlier.

In 1809, Thomasina CoVERly, the daughter of the house, is a precocious teenager with ideas about mathematics well ahead of her time. She studies with her tutor, Septimus Hodge, a friend of Lord Byron (who is an unseen guest in the house). In the present, a writer and an academic converge on the house: Hannah Jarvis, the writer, is investigating a hermit who once lived on the grounds; Bernard Nightingale, a professor of literature, is investigating a mysterious chapter in the life of Byron. As their investigations unfold, helped by Valentine CoVERly, a post-graduate student in mathematical biology, the TRUTH about what happened in Thomasina's lifetime is gradually REVEalED.

The play's set features a large table, which is used by the characters in both past and present. Props are not removed when the play switches time period, so that the books, turtle, coffee mugs, quill pens, portfolios, and laptop computers appear alongside each other in a blurring of past and present.

The genre of Arcadia is, at the surface, a drama in the specialized, modern sense of being somewhere between a tragedy and a comedy. It involves some elements of classical tragedy—"noble" characters and the audience's knowledge of Thomasina's impending death—but the predominant element is comedy, in the way that the characters interact with each other and their witty, epigrammatic dialogue.

The title is an abbreviation of an initial, pre-publication, title: "Et in Arcadia ego" (with Arcadia referring to the pastoral ideal of Arcadia), a phrase most commonly interpreted as a memento mori spoken by Death. The phrase translates as "and in Arcadia I am", frequently rendered as "I [Death] too am in Arcadia" or "Even in Arcadia I [Death] am", although the meaning of the phrase is enigmatic. Discussing paintings of pleasant landscapes, Lady Croom mistranslates the phrase as "here I am in Arcadia", on which Thomasina drily comments, "Yes Mama, if you would have it so". Thomasina's tutor Septimus notices; later, knowing that she Will appreciate the TRUE meaning, he offers the translation "Even in Arcadia, there am I". He is right: "Oh, phooey to Death!" she replies. In a more obvious sense, the title also alludes to the ideal of nature as a rustic paradise, with the landscaping of the estate to give a less stylised, irregular form as a major theme in the play. This serves as a recurring reference to the different ways in which "TRUE nature" can be understood, and as a pragmatic parallel to Thomasina's theoretical method of describing the structure of the natural world using mathematics.>>

[orin stepanek]

I liked the video; music was OK.

[Dustin]

Whoa I'm getting seasick. Holding on to my chair.
Nice sky video that puts earth in it's place. Not the center of the universe. Galileo would love it.

Dustin

[ukei]

This video looks just like we're on the surface of a spaceship... a really cool "Spaceship Earth."
just awesome keep it up APOD.

[Steve Dutch]

Note the scenes where the Milky Way is flat along the horizon. At that moment, the South Galactic Pole is directly overhead.

[emc]

I enjoyed this APOD! It’s cool to see the Earth movement perspective from approximate space. Clever idea… now excuse me while I experience diurnal.

[NoelC]

Two thumbs up from me! I love being shown alternate perspectives!

-Noel

[Ann]

The video reminds me very strongly of one of the defining moments that turned me into a diehard astronomy nerd.

It was 1970 or 1971, a crisp and clear winter night. Snow on the ground. I had just read about the Andromeda galaxy, that it was high in the sky and you could see it just fine with a pair of binoculars. My parents had a pair of binoculars, and I decided to go out and find the galaxy.

Well, this was the first time ever that I had watched the sky through binoculars. I was frustrated and confused at the small field of vision. A bright star would suddenly sail into view as I moved my binoculars a little, and then another, but I had no idea which ones they were.

I stood there for a while trying to aim my binoculars just so, but eventually my arms got just too tired. So I went inside and got myself a blanket that I spread on the ground. Now I could lie down on the ground on top of the blanket and rest my arms. But, wow! What a feeling that was, lying down on the snowy ground, feeling every inch of my body touch the ground, and feeling, as it were, the enormous sphere of the Earth curving away from me on all sides. And yet, even though the Earth was enormous compared to me, it was so incredibly, unbelievably tiny compared with the glittering blackness that stretched away to infinity above me, as I stared straight into this endless blackness. And I could feel, I could imagine, how the enormous yet tiny sphere of the Earth was like a sailing ship in the night, sailing along in the cosmos, floating inside it. I could almost feel the Earth turn, and I could almost see the stars move along grand celestial arcs above me, although I and the Earth were really the ones that were moving. And yet it moves, as Galileo said!

But the blackness that I was staring into wasn't all black. Back then, it didn't occur to me that stars could be blue, so as I swept my binoculars over stars with solidly negative (blue) color indexes - Alpha Andromedae, Pi Andromedae, Nu Andromedae - I didn't see that they were blue, but only brilliantly, icy white. So when I suddenly, and after a very long time of trying, finally found M31 as it sailed from nowhere into my field of view, I'm sure I gasped out loud. Where the stars had been brilliant points of icy white, the galaxy was soft, extended and yellowish. It was yellowish! I'm not kidding you! I can't explain how the soft texture and yellow color moved me, because these qualities made it so overwhelmingly obvious that the object that I had finally found in that ocean of blackness was a different thing that the stars. It was, rather, billions of stars. Billions and billions. And I was looking at all these stars all at once.

And I felt, again so strongly that I can't put it in words, that there was someone there inside that yellow softness. Not so that I felt a mystic "connection" with someone in that blurry spot. Not so that I felt the actual "presence" of someone. But I knew that I was looking at billions and billions of stars all at once, and I felt so strongly that I can't put it in words, that there was someone in there. At least one star out of the billions and billions that I was looking at all at once had a planet that was like the Earth, and there were people on that planet that were at least a bit like us. I was totally certain of it.

Now I'm not so sure. What I saw back then was the yellow bulge of M31, and I'm no longer at all sure that bulges are ideal places for habitable planets. I'm not sure of that at all. When I have thought back on that night, I have felt less and less certain that the yellow softness that I could see in my binoculars actually contained any advanced life forms at all. Of course, the actual life-friendliness or lack of it of planets in the bulge has nothing whatsoever to do with what I might think of it, so my first impression may have been right, for all I know: maybe there was someone in that yellow softness after all.

One thing is certain: I'll never forget the magic of that night. And I have been an astronomy nerd ever since.

I couldn't find any nice pictures to illustrate my story, but...



This is not me, because it's a guy. And it's broad daylight here. But he will have to do, because it is surprisingly difficult to find pictures of people lying on the ground watching the sky.

Click to view full size image

This clearly isn't the Earth, but it brings home the idea of the Earth as a small sphere floating in a big "skyscape".

Ann

[Wolf Kotenberg]

at 40 seconds, what was being lasered ?

[neufer]

at 40 seconds, what was being lasered ?

http://apod.nasa.gov/apod/ap100906.html

<<I love the shots of the observatories shooting orange lasers out their domes (here’s a gorgeous hi-res photo of it). They’re fending off attacks by the Goa’uld, Ori, and Wraith using those to help counteract atmospheric distortion; the laser hits a layer of sodium atoms high in the atmosphere and causes them to glow. This creates a bright artificial star in the telescope’s view, which jiggles and wiggles as the atmosphere roils. The way the "star" moves can be counteracted by the telescope, sharpening up the image it makes. This tech, called adaptive optics, has revolutionized high-resolution ground-based astronomy. It has also given the VLT the ability to make incredibly sharp and gorgeous images.>>

[NoelC]

I notice the laser is off sometimes... Is that when there's a sufficiently bright "guide star" in the field of view that the laser is not necessary?

-Noel

[islader2]

Since ANN and OWL like the music, I withdraw my comment about the bad music. ANN and OWL often are more sagacious that APOD itself.

[Beyond]

-(here’s a gorgeous hi-res photo of it).

WOW! The laser must be on long range auto-tracking. I can't see a Goa'uld ship anywhere.

[Chris Peterson]

I notice the laser is off sometimes... Is that when there's a sufficiently bright "guide star" in the field of view that the laser is not necessary?

Maybe. But not all images are made using the AO system. It depends on the wavelength and the FOV. AO is mainly used for IR, and only works for very narrow fields (a few arcseconds). So I'd expect that a normal imaging session, covering a range of targets, would only use the laser sometimes.

[BulletPeople]

Thank you a great deal for posting my minor edit of the excellent original video by Salgado and Guisard at ESO.

One thing that has gotten little comment and to me was the most fascinating result of this switched perspective is the distortion of the stars that occurs. Some people have guessed that it is lens distortion, but to me it appears to follow the horizon and I wonder if it is the lens effect caused by the atmosphere. This is not noticeable in conventional time lapse clips but really stands out here.

Also, is anyone familiar with other time lapse clips of the sky from NASA or some other government entity who would not object to my using their original footage to produce more of these? The ones I have done that I can't share publicly are absolutely mesmerizing and I would love to be able to produce some that could be shared freely.

Nick D'Orazio
BulletPeople.com

[bigrbigr]

very cool, as "noel" said (prespective) that was my first look at that cind of angle. it just puts a difrent look at how small earth truly is. almost like a astronauts view, but close up!

very cool!