Shuttle and Hubble Passing In Front of the Sun 161
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.
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: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?
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]
Re:fake? (Score:3, Informative)
NASA [nasa.gov]
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.
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.
Re:Reminds me... (Score:5, Informative)
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.
Re:Fly (Score:5, Informative)
Re:Shocking fact (Score:2, Informative)
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.
Actually we know all the distances so we can calculate how much bigger should the sun look than the shuttle in this picture.
Distance from Sun =1.496 x 10^11 m
distance form hubble=5.59*10^5
size of the sun=4.37*10^9
size of shuttle=5.6*10
Simple math says that the sun should look 291 times bigger, but this assumes that the sun was right on top when the picture was taken and that the shuttle was in horizontal position.
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.
Re:Crappy quality (Score:2, Informative)
Limb darkening (Score:5, Informative)
http://en.wikipedia.org/wiki/Limb_darkening [wikipedia.org]
http://en.wikipedia.org/wiki/Black_body [wikipedia.org]
smaller! Re:small (Score:2, Informative)
Pah, if you want to feel more insignificant, hop on over to images.google.com and look at (in order): "globular cluster", "M31 Andromeda", "M31 Andromeda +halo", and "Hubble Ultra Deep Field" (HUDF).
Bear in mind that when you see a spiral galaxy in HUDF or in the deeper part of the M31 Andromeda halo deep exposure, you are seeing a galaxy about the size of M31, with about a trillion stars about the size of the one in the picture that is already making you feel insignificant relative to the "greater universe".
HUDF, btw, is a rather small fraction of the sky, subtending a solid angle of about 10% the size of the full moon. The sky looks about the same (filled with galaxies) in all directions where we don't have stars and dust clouds in the way. HUDF also only shows what could be picked up during the exposure time; a longer exposure would show still more galaxies at all ranges. Finally, HUDF shows human-visible wavelengths only; there are lots more galaxies visible in longer wavelengths, for a variety of reasons (mainly related to angle, occlusion and the Hubble Flow).
Something to think about the next time a science fiction character or superhero talks about destroying or saving the universe...
Re:Fly (Score:2, Informative)
A sphere has more of its surface pointing directly at you near whatever point you see as the center. As your eye moves towards the edges more and more of the surface is pointing more and more away from your eye, and thus less light is emitted to your eye and it appears less bright. As the sun is SO bright that you cannot look at it, or notice the difference in brightness, without a huge amount of filtering you will only see this effect if you look at a photo, or through a telescope, with a huge filter made specifically for looking at the sun.
This same effect can be seen of any evenly lit spherical light, and even on an evenly lit sphere that is just reflecting light. This is an effect known to virtually any serious artist, much like artists study perspective and shadow casting, to make their art more realistic. You see the same effect on cylinders, they seem brighter in the middle than the edges.
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
Re:Crappy quality (Score:3, Informative)