GvG was one of several readers to point out this "incredible photo clearly showing the silhouette of Atlantis and the Hubble Space Telescope as they passed in front of the Sun was taken Wednesday, May 13, 2009, from west of Vero Beach, Florida. The two spaceships were at an altitude of 600 km and they zipped across the sun in only 0.8 seconds." The image is all over the Web now, for good reason.
Reminds me of the scene in the new Star Trek movie with all the people escaping from the Enterprise, and you see the scene with a massive star behind them, and they look like tiny specks against it.
Your understanding seems off -- the picture we're discussing is a photograph in every sense. "Trick of perspective" is an odd way to speak of it, since the perspective is simply that as visible from the ground, where the photo was taken.
From the link: "Thierry made this image using a solar-filtered Takahashi 5-inch refracting telescope and a Canon 5D Mark II digital camera." If that's not a photo, then what is?
That's so fucking obvious I don't see why you felt the need to mention it, unless you think everyone else is stupid. My hat blocks the sun, but that never made me think the sun is turnip sized.
more to the point: why does the brightest object in the solar system have nice shading effect to make it look spherical?
I accept that this photo has been certified legit, but that shading screams fake to me because the sun should only look like a flat disc. So the question I'm asking astronomers is to explain why the sun appears spherical instead of like a big flat bright disc?
I don't know *why*,
but that is indeed what the sun looks like if you watch it heavily filtered in a telescope,
or use a telescope to project it on a surface.
The edge like that because you see a shallower, thus cooler, portion of the sun's photosphere. As a cooler source of blackbody radiation, it looks darker and more orange. The phenomena is called limb darkening.
We see spherical objects as spherical because of the shadows and light reflected from it causing different intensities of light reaching our eyes from it.
The sun is different, it has no shadows or light landing on it. It is the light source. If you assume that the sun is a black body of a constant temperature across its surface, the light reaching us from anywhere on its surface is constant which would make it appear to be a completely flat disc. This effect is due to two cos(theta) terms cancelling each other out if you want to do the maths and would be true no matter what the shape that the sun (or any perfect black body) actually was. If for example, the sun was a cube, we would just see the silhouette of the cube as a flat surface and none of the sides.
Now, in reality, the sun isn't a perfect black body of constant temperature and is both less dense and cooler at the edges than at the centre. This makes the edges darker and makes it look more like a spherical object. The post below on limb darkening gives the details.
Do we actually have satellites in that high orbit?
Yes. The STEREO-B satellite is in a heliocentric orbit (i.e., centered on the Sun, not the Earth) outside the Earth's orbit, gradually getting farther behind it because the period of an orbit increases with distance from the Sun. That picture was taken early in the flight, when the geometry still permitted seeing the Moon and Sun in line; it won't happen any more.
Its partner, STEREO-A, is in an orbit inside the Earth's, and gradually getting ahead for the same reason. As the two diverge, they can image the Sun simultaneously and take 3-D pictures of it.
My first thought was "oh geez! with all the camera technologies we have these days, that's the best we could get??" I want voyeuristic photos of naked female astronauts with 0-g boobs. Give us some serious zoom!
Yes, who would have thought that the Sun, the star around which would rotate, would be SOOOOO much bigger than a space vehicle and a space telescope. Next thing you know we'll have pictures showing how tiny people and cars look seen from space compared to the hugeness of Earth.
When seeing a picture of a two-thousand ton manned space ship next to a space telescope with a huge nanometer accuracy mirror being repaired by a crew of people in space suits all whizzing through space with a class G star looming in the background, "simple" was not exactly the first thing which came to my mind.
This photo is actually of comparable quality to what you'd get from NASA, given the same conditions under which it was taken under.
Bear in mind that the photo is being taken through many, many miles of air, during the daytime, and the daytime heat causes all kinds of instabilities in the air that will show up as waviness in the image (the same phenomenon causes stars to twinkle at night). Finding steady air at night is hard enough, but getting images this clear during the day is remarkable, even taking the quick shutter speed into account.
Also bear in mind that the Sun is only about 30 arcminutes across as seen from the Earth, meaning that the Shuttle silhouette itself is at most just a very few arcseconds in size. To put it in perspective, it's on the order of getting a clear photo of the text "In God We Trust" on a dime from the other end of a (US) football field while the dime is moving at 4 feet or so per second.
The photo is noteworthy for a number of reasons. Among them:
1) This was done by a guy with a portable telescope and camera that he carts around in the back of his car, not a mountaintop observatory or mega-million satellite.
2) You had to be in exactly the right place at the right time. That is, in a line a few km long for the less-than-one-second that the transit took place.
3) You have to know how to photograph the Sun without frying your equipment or going blind. You need enough magnification to resolve the spacecraft but not so much to miss the target.
4) For a non-professional, this photo took an impressive amount of equipment, configured properly and operated perfectly.
And it's no fake. There's another photo showing the Shuttle and the ISS transiting the Sun and the two are very similar. In that photo, the ISS is the more prominent object.
While I realize the difficulty of actually taking this picture, am I the only one who thinks this picture is actually really terrible quality? Or am I just used to much better quality from NASA photos?
They're up there to *fix* the hubble. They haven't actually fixed it yet...
west of vero beach is the stomping grounds of nasa engineers. I was in melbourne (like a 20 minute drive from vero beach) this past weekend and spoke with a few engineers who worked for nasa through contracts. That entire area is known as the "space coast". This was probably taken by an ex-nasa engineer or photographer. About month ago when I was up there was a rocket launch and there were probably 5-10 nasa guys in the street watching it. That area is absolutley saturated with guys who have an interest in nasa's activities and the professional know-how to do such things. While it could still be a hoax, there is nothing physically impossible and the location of origin of the photo only lends credibility.
Astronomy Picture of the Day (Score:5, Informative)
It was todays astronomy picture of the day!
http://antwrp.gsfc.nasa.gov/apod/astropix.html
Re:Astronomy Picture of the Day (Score:5, Insightful)
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Re:Astronomy Picture of the Day [ISS] (Score:5, Interesting)
Here's one with the space-station taken a few years ago:
http://apod.nasa.gov/apod/ap060921.html [nasa.gov]
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Re:Astronomy Picture of the Day (Score:5, Interesting)
nary a sunspot
no faculae here at all
last chance to see this
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Reminds me... (Score:4, Interesting)
Re:Reminds me... (Score:5, Funny)
...my eye's...I can't see anymore...
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Re: (Score:3, Funny)
may I suggest that you try the goggles?
Re:Reminds me... (Score:5, Informative)
Your understanding seems off -- the picture we're discussing is a photograph in every sense. "Trick of perspective" is an odd way to speak of it, since the perspective is simply that as visible from the ground, where the photo was taken.
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Re:Reminds me... (Score:5, Informative)
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Re: (Score:3, Funny)
Re:Reminds me... (Score:5, Funny)
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Re:Reminds me... (Score:4, Funny)
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Fly (Score:3, Funny)
is that me or is that a housefly on an orange.
Re: (Score:3, Funny)
It's just you.
It's actually a mosquito on a grapefruit.
Re:Fly (Score:5, Informative)
I don't know *why*, but that is indeed what the sun looks like if you watch it heavily filtered in a telescope, or use a telescope to project it on a surface.
Parent
Limb darkening (Score:5, Informative)
http://en.wikipedia.org/wiki/Limb_darkening [wikipedia.org]
http://en.wikipedia.org/wiki/Black_body [wikipedia.org]
Parent
Re:Fly (Score:4, Insightful)
IANAA, but the sun appears spherical instead of like a big flat bright disc because it is indeed a spherical object - not a big flat bright disc.
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Re:Fly (Score:5, Informative)
Sensible question but a non obvious answer.
We see spherical objects as spherical because of the shadows and light reflected from it causing different intensities of light reaching our eyes from it.
The sun is different, it has no shadows or light landing on it. It is the light source. If you assume that the sun is a black body of a constant temperature across its surface, the light reaching us from anywhere on its surface is constant which would make it appear to be a completely flat disc. This effect is due to two cos(theta) terms cancelling each other out if you want to do the maths and would be true no matter what the shape that the sun (or any perfect black body) actually was. If for example, the sun was a cube, we would just see the silhouette of the cube as a flat surface and none of the sides.
Now, in reality, the sun isn't a perfect black body of constant temperature and is both less dense and cooler at the edges than at the centre. This makes the edges darker and makes it look more like a spherical object. The post below on limb darkening gives the details.
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Re:Fly (Score:5, Informative)
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Re: (Score:3, Interesting)
It doesn't. Look at the image showing the whole sun - it's dark on all sides.
Transit (Score:5, Interesting)
Re:Transit (Score:5, Funny)
That's no moon....
Parent
Re: (Score:3, Funny)
... It's the Eye of Sauron.
Re:Transit (Score:4, Informative)
Yes. The STEREO-B satellite is in a heliocentric orbit (i.e., centered on the Sun, not the Earth) outside the Earth's orbit, gradually getting farther behind it because the period of an orbit increases with distance from the Sun. That picture was taken early in the flight, when the geometry still permitted seeing the Moon and Sun in line; it won't happen any more.
Its partner, STEREO-A, is in an orbit inside the Earth's, and gradually getting ahead for the same reason. As the two diverge, they can image the Sun simultaneously and take 3-D pictures of it.
rj
Parent
Re: (Score:3, Insightful)
small (Score:5, Interesting)
My first thought was that the picture is a reminder of our insignificance relative to the greater universe (and even the quantum universe).
But what daring goes into these missions! Tiny we may be but we have great ambition.
Re: (Score:3)
My first thought was "oh geez! with all the camera technologies we have these days, that's the best we could get??" I want voyeuristic photos of naked female astronauts with 0-g boobs. Give us some serious zoom!
Re: (Score:3, Funny)
You know how boobs sag?
Imagine that sagging upward.
Or outward.
Re:small (Score:4, Funny)
Yes. But, some are longer than others.
Parent
Re:small (Score:5, Interesting)
a reminder of our insignificance relative to the greater universe
You may have seen this already, but it is still an amazing video emphasizing this point: http://www.youtube.com/watch?v=855LIxE0qP0 [youtube.com]
Parent
Shocking fact (Score:5, Interesting)
I find the most eye opening fact is that the sun is 93,000,000 miles behind the shuttle. It is an awesome display of the scale of the sun.
Re:Shocking fact (Score:4, Funny)
Parent
I didn't think... (Score:5, Funny)
I wondered (Score:4, Funny)
That explains it. I wondered what that fleeting shadow was.
I could see more clearly (Score:4, Funny)
I could see more clearly what was going on if they just cleaned off those two little black specks in the picture.
It's amazing... (Score:4, Insightful)
Simple??? (Score:5, Interesting)
When seeing a picture of a two-thousand ton manned space ship next to a space telescope with a huge nanometer accuracy mirror being repaired by a crew of people in space suits all whizzing through space with a class G star looming in the background, "simple" was not exactly the first thing which came to my mind.
Parent
Fail. (Score:5, Funny)
Re:fail (Score:4, Funny)
thats because god used coreldraw
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Re:fail (Score:5, Funny)
I think you need to spend more time staring at the Sun. Big yellow orb? Check.
Parent
Re:Crappy quality (Score:5, Informative)
This was done with a refracting telescope and a digital camera, and it happened in 0.8 seconds.
What, exactly, were you expecting?
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Re:Crappy quality (Score:5, Informative)
Its not a NASA photo.
http://www.astrophoto.fr/ [astrophoto.fr]
Thierry Legault is a guy with a telescope and camera.
Your not supposed to look directly at the sun and this guy points a telescope at it. I think its pretty good. Who knew what the sun would look like with a shutter speed of 1/8000 sec.
http://blogs.discovermagazine.com/badastronomy/2009/05/15/check-this-out-amazing-photo-of-the-sun/ [discovermagazine.com]
Parent
Re:Crappy quality (Score:5, Interesting)
Bear in mind that the photo is being taken through many, many miles of air, during the daytime, and the daytime heat causes all kinds of instabilities in the air that will show up as waviness in the image (the same phenomenon causes stars to twinkle at night). Finding steady air at night is hard enough, but getting images this clear during the day is remarkable, even taking the quick shutter speed into account.
Also bear in mind that the Sun is only about 30 arcminutes across as seen from the Earth, meaning that the Shuttle silhouette itself is at most just a very few arcseconds in size. To put it in perspective, it's on the order of getting a clear photo of the text "In God We Trust" on a dime from the other end of a (US) football field while the dime is moving at 4 feet or so per second.
Parent
Re:Crappy quality (Score:5, Funny)
Bear in mind that the photo is being taken...during the daytime...
Definitely should have taken the picture at night.
Parent
Re:Crappy quality (Score:5, Informative)
1) This was done by a guy with a portable telescope and camera that he carts around in the back of his car, not a mountaintop observatory or mega-million satellite.
2) You had to be in exactly the right place at the right time. That is, in a line a few km long for the less-than-one-second that the transit took place.
3) You have to know how to photograph the Sun without frying your equipment or going blind. You need enough magnification to resolve the spacecraft but not so much to miss the target.
4) For a non-professional, this photo took an impressive amount of equipment, configured properly and operated perfectly.
And it's no fake. There's another photo showing the Shuttle and the ISS transiting the Sun and the two are very similar. In that photo, the ISS is the more prominent object.
Parent
Re: (Score:3, Informative)
Re:Crappy quality (Score:5, Funny)
While I realize the difficulty of actually taking this picture, am I the only one who thinks this picture is actually really terrible quality? Or am I just used to much better quality from NASA photos?
They're up there to *fix* the hubble. They haven't actually fixed it yet...
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Re:Crappy quality (Score:5, Funny)
Sure kid, I got one for ya [theknack.net].
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Re:fake? (Score:5, Interesting)
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Re: (Score:3, Informative)
NASA [nasa.gov]