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95 Comments
- Oatlord, on 11/29/2008, -1/+63Did the headline of this Digg link really require the exclamation points? I think a headline like "the moon is set to explode" or "oh *****, the moon is on fire" would be more fitting headlines for exclamation points than this.
- kirtap, on 11/30/2008, -2/+54365.25/27.32 = 13.37
science is elite - Pinkertinkle, on 11/30/2008, -0/+46The moon is earth's bitch, I don't even want to think about it orbiting some other celestial body.
- kplo, on 04/01/2009, -1/+37Wow. That's easily the most obvious thing I've seen lately. And by most obvious, I mean I completely would've guessed wrong had I been asked on the spot.
- JYoungest1, on 11/29/2008, -6/+32Looks a lot like Uranus.
- MCA2142, on 11/30/2008, -2/+25Sir we concluded that the "Bird" is equal to or greater than the "word."
- LBobRife, on 11/29/2008, -0/+18Interesting article. I've never thought about what the moon would look like in its orbit around the sun.
- displacednomad, on 11/29/2008, -0/+17Ow. Brain hurts.
- NathanielJ, on 11/30/2008, -3/+17How can such an interesting and smart article be submitted with such a mind-numbingly stupid headline?
- agbullet, on 11/30/2008, -0/+11hah! but the sun is on fire!
i r smaert. - inactive, on 11/30/2008, -1/+10I gave up after 3rd sentence.
- breakaway, on 11/30/2008, -0/+7Why does America still use imperial units?
- Visual77, on 11/30/2008, -2/+8Holy *****.
I'm a fairly intelligent guy with only moderate math experience (only up to high school Calculus) and no specialized astronomy training, and I never would've thought the moon loops back on itself. That drawing shows the orbit of the moon being about 0.2 AU. They can't be serious that actual, trained mathematicians would EVER think the moon doubles back on itself. That's insane (read: moronic). - cjh24, on 11/30/2008, -0/+6I can't believe how wrong you are.
The Moon DOESN'T travel 'backwards' in it's orbit around the sun, that would require the distance from the Earth to the Moon to be emense, and for it's orbital velocity to be higher than that of the Earth around the Sun.
Imagine to people racing around a track. As one (A) overtakes the other (B), does B stop, or go backwards?
Nice diagrams though. - jerbaker, on 11/30/2008, -3/+8Um, there is a problem with the logic.
"The speed of the Earth around the Sun is about 30 times the speed of the Moon around the Earth. That means that the speed of the Moon around the Sun will vary between about 103% and 97% of the speed of the Earth around the Sun."
Am I missing something? Imagine you're an observer on the surface of the Sun, and you're watching the Earth and the Moon along the Moon's orbital plane. Say on your first day of observation the moon is at the far left side of its orbit as seen from your vantage point, and the Earth is traveling towards the left on its orbit around the Sun.
o <----Moon O <----- Earth
The moon is going to have to move in the opposite direction as the Earth in order to transit the Earth and "get to the other side."
O <----- Earth o <----Moon
According to the author's claim, this can't happen. If it did, then the Moon's orbit as viewed from the Sun would indeed look like a spiral. It's called retrograde motion and it happens in astronomy all the time http://www.lasalle.edu/%7Esmithsc/Astronomy/retrog ... - rald84, on 11/30/2008, -0/+5THIS! IS! DIGG!
- primehifi, on 11/30/2008, -0/+5YES! IT! DID!
- Goonder, on 11/30/2008, -0/+4Both.
- Mizzark, on 11/30/2008, -1/+5You lost me on the swirls. O.o
- tnoy, on 11/30/2008, -2/+6Because we want to.
- AlucardZero, on 11/30/2008, -1/+513.37
- heavyd14, on 11/30/2008, -1/+4Social Momentum. Sure, I'd love to use metric, but I wouldn't have a clue about how warm it was outside if it were given in C, how meters tall I am or my mass in kilograms.
- agbullet, on 11/30/2008, -0/+3@aptanalogy
The Point, dude. You're missing it. - jasdf, on 11/30/2008, -1/+4I guess I've never thought about that before, but now that I see it I doubt I'll ever forget. I LOVE science on Digg, we are just a bunch of geeks anyway right?
- farfromhere, on 11/30/2008, -1/+4I was prepared to file this under "who gives a *****," but then I actually read the article.
Fascinating stuff. - Petrushka72, on 11/30/2008, -0/+3That image is incorrect. As the article states clearly -- and this is much more interesting than the absence of any retrograde motion -- the orbit of the moon around the sun is completely convex. It doesn't wiggle back and forth as that image implies.
- jcsw, on 11/30/2008, -0/+3Interesting but completely pointless. Just how I love my comments.
A+, would read again. - joe8pack, on 11/30/2008, -0/+3my research shows the moon's orbit to be a cube in 7 dimensions. Of course I cheated and used the square root of jupiter's orbit minus pi cubed over the distance between first and third and I was drinking heavily at the time.
- ledwyn, on 11/30/2008, -1/+4I had not thought of that, but now I am tempted (almost) to do the math to see if any satellite can 'loop back on itself'. I'm fairly sure it is not even possible to get an artificial satellite to do that without active propulsion.
- ryan631, on 11/30/2008, -0/+3proportionally to the affect on the price of tea in china.
- jerbaker, on 11/30/2008, -0/+3You're not getting it. How do you propose the Moon start in front of the Earth, and then end up behind the Earth, if it does not *appear* to move backward? I'm not sure why retrograde motion seems unbelievable to you. It is a regularly observed astronomical phenomena and it's real.
If you're imagining seeing the Earth speed past the Moon, and then the Moon speeding past the Earth in alternate fashion, perhaps you are imagining a frame of reference independent of the Sun, the Moon, and the Earth? When you say the Moon will only appear to slow down and speed up, you mean relative to what? - klitzbtc, on 11/30/2008, -1/+4I thought the moon couldn't catch fire since there's no oxygen in space.
- audiophiliac, on 11/30/2008, -0/+3I almost couldn't hold it in once I saw this lmao
- 80hd, on 11/30/2008, -0/+3at least you're honest.
- iMiXiMi, on 11/30/2008, -0/+3I'm doing this in physics right now,
cool how i can understand something now that i would have murdered myself trying to understand 2 months ago. - captainchris, on 11/30/2008, -0/+3seeing that the moon is made of cheese, and guatemala has no investments in spacial cuisine...
- inactive, on 11/30/2008, -1/+3And this affects the price of cheese in Guatemala how, exactly?
- Fordi, on 11/30/2008, -0/+2Oxygen isn't the only possible agent to provide combustion - it's just the most available and easiest.
Still, you can have a lot of fun with Cesium if you're not careful. - GUTTS, on 11/30/2008, -0/+2It turns out that we loops when d < p, a wiggly path when p < d < p^2 and a convex path if p^2 < d. = IDGAF!
- NathanielJ, on 11/30/2008, -0/+2...what more did you want? He gave two different proofs (well not exactly formal proofs, but he went through all the calculations for you).
- joe8pack, on 11/30/2008, -0/+2and they are all borne upon the back of a giant tortoise.
- ishotthedoor, on 11/30/2008, -0/+2Lousy Smarch weather
- mytCbumps, on 11/30/2008, -0/+2Serious buzz kill!
- inactive, on 11/30/2008, -0/+2You had Miss Barthelow too?
- klitzbtc, on 11/30/2008, -0/+2This is what happens, I say something intentionally stupid and what does it create: more stupidity.
I fail. - zambuka, on 11/30/2008, -0/+2It all depends on how you observe the Earth/Moon system. If you stood at the centre of the Earth's orbit and rotated so that the Earth would always remain in the centre of your view then the Moon would appear have this retrograde path in relation to the Earth.
However, if you were instead to stand on the surface of the sun and observe a section of the sky and follow as the Earth tracked from one horizon to the next then the Moon's speed would appear to pulse in its path going faster and slower depending on its current orbital position. When the Moon's orbital path has the Moon travelling in the same direction as the Earth's orbit it would appear to move slightly faster than the Earth. In the other half of the Moon's orbit, the part that has it travelling counter to the Earth's orbit the moon would appear to slow down in its path. However, because the Moon's orbital speed around the Earth is much slower than the Earth's orbital speed around your chosen point of view, the surface of the sun, the Moon would never actually appear to go backwards in its path.
You would observe a similar "pulsing" effect if your observation point were a point above the eliptic so you were looking down from "above" watching the Earth and Moon on their path about the Sun.
As for retrograde motion, well that is an interesting anomoly due to the fact that your point of observation is also in motion. In the example of Mars you see the retrograde path because both the Earth and Mars are in motion around the sun and your observation point is the Earth. There would be no retrograde path if you were observing the path of Mars from either a point above the eliptic or a point on the Sun. Take a good look at the Copernican model in the link you used.
Essentially, the path you observe is dependant entirely of the way you observe and where you take your observations from. However this observed path, most particularly the retrograde Mars path, is not the same as the actual physical path these celestial bodies take, which is what this paper is discussing. - inactive, on 11/30/2008, -0/+2by + or - 17 pesos.
- Fordi, on 11/30/2008, -0/+2The moon orbits the earth. The earth-moon subsystem orbits the sun.
- Gemfinder, on 11/30/2008, -0/+2There used to be more zodiac signs than the 12 we know now. According to different scholars, they usually fall between Scorpio and Sagittarius and they were Pegasus, Lupus and Aquila.
The way they addressed that was to separate Scorpio into a hierarchy of three signs: Scorpio, Lupus and Aquila. You're born a Scorpion; at some stage in your life, you undergo a psychospiritual change and then you're a Wolf; finally the Wolf changes into the Eagle and ascends to Heaven.
With the discovery of a thirteenth month, we could bring back Pegasus and put him between the Scorpio triad and Sagittarius. The trade-off is we wouldn't have Full-Moonless years (February 1865) nor would we have Blue Moon months. - Mpwns, on 11/30/2008, -0/+2so the moon has a smarch month?
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