Starship Asterisk*

Eclipsing the Sun

Explanation: Skywatchers throughout much of Europe, North Africa, and Central Asia, were treated to the first eclipse of the new year on January 4, a partial eclipse of the Sun. But traveling to the area around Muscat, capital city of Oman, photographer Thierry Legault planned to simultaneously record two eclipses on that date, calculating from that position, for a brief moment, both the Moon and the International Space Station could be seen in silhouette, crossing the Sun. His sharp, 1/5000th second exposure is shown here, capturing planet Earth's two largest satellites against the bright solar disk. As the partial solar eclipse unfolded, the space station (above and left of center) zipped across the scene in less than 1 second, about 500 kilometers from the photographer's telescope and camera. Of course, the Moon was 400 thousand kilometers away. Complete with sunspots, the Sun was 150 million kilometers distant.

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GADS!! What timeing, and such fast reflexes!! Amazing to say the least.

381 m ~ Empire State Bld.
395 km ~ ISS
395 Mm ~ Moon
148 Gm ~ Sun

Congratulations, Thierry, for that photo.
I know the difficulties to hit the correct timing as the ISS takes about 0.7 secs across the sun in the best case.

I took a photo like this during the Oct. 3rd, 2005 eclipse in denmark, together with Bernd Schatzmann, but id didn't have that quality, however.
You can read the story (in German) here: http://www.astrotreff.de/topic.asp?ARCH ... C_ID=29051

Regards, mike

Thierry, congratulations on your APOD!

Fantastic photo of two in one eclipse.
These event require much planning and luck, even the weather conditions.
Greetings
César

APOD Robot wrote:...for a brief moment, both the Moon and the International Space Station could be seen in silhouette, crossing the Sun

And there was me thinking, "Incoming Tie Fighter!!!"

Does anyone else think the International Space Station looks like the Canadian flag?

zorro wrote:Does anyone else think the International Space Station looks like the Canadian flag?

Maybe an omen - Canada vs Russia hockey game's today? Go Team ISS!

Stupid question: Why is the sun yellow in this photo and so many others?

I am looking at that picture, and I'm thinking y smart people of the APOTD can be making a mistake this grossly bad!

This does not to me look like the ISS crosing the disk of the sun. it looks like Hubble that is in transit!

Yes?

it' far too small and not complex enough for ISS, yet the profile matches Hubble perfectly!

Joe
nss@mwt.net

WOW I've never seen anything like that before. Way to go Thierry.

Redstone wrote: Yes?

No. Here is another of Thierry's image, also an APOD, of the ISS and space shuttle transitting the sun:
http://apod.nasa.gov/apod/ap100523.html

And another ISS transit image from other photographers: http://www.astronomycamerasblog.com/2010/08/16/

And another: http://www.astrophoto.com.mx/picture.ph ... category/6

So... not the Hubble.

It does resemble the Canadian flag, though!

Dan Schroeder wrote:Stupid question: Why is the sun yellow in this photo and so many others?

The Sun is yellow when viewed directly (with sufficient filtering to avoid saturation). How yellow it appears depends on the type of filter used. A very common type of metal coated glass filter gives an even stronger yellow cast than the Sun by itself has. And finally, many imagers simply prefer to add yellow or orange to make what would otherwise be a nearly B&W image more colorful.

DCStone wrote:

APOD Robot wrote:...for a brief moment, both the Moon and the International Space Station could be seen in silhouette, crossing the Sun

And there was me thinking, "Incoming Tie Fighter!!!"

That's exactly what I thought when I first saw it!

Kudos to Thierry Legault - what a great picture!! I'm amazed at the planning, calculations, timing that had to go into getting this photo! The clarity is wonderful!

But I'm curious - 1/5000 second is beyond human reflexes (at least it is beyond mine) - is this photo taken with some kind of ultra-high-speed video camera and then a specific frame selected for display?


P.S. what is a tie-fighter?

biddie: http://en.wikipedia.org/wiki/TIE_fighter

(You have some ordering to do at Netflix! <g>)

Redstone wrote:I am looking at that picture, and I'm thinking y smart people of the APOTD can be making a mistake this grossly bad!
This does not to me look like the ISS crosing the disk of the sun. it looks like Hubble that is in transit! Yes?
it' far too small and not complex enough for ISS, yet the profile matches Hubble perfectly!

Having seen the ISS transit the sun and the moon visually through a telescope a number of times, as well as having seen the ISS visually through a telescope in the open sky a number of times, I can also add that today's APOD does indeed show the ISS, not the HST.

The profile does not match the HST, which has relatively small solar panels compared to the body of the spacecraft, as shown here:

http://en.wikipedia.org/wiki/Hubble_Space_Telescope

In contrast, the ISS has relatively large banks of solar panels as shown here:

http://en.wikipedia.org/wiki/Internatio ... ce_Station

The apparent size of the ISS can vary considerably since it is currently about 350 km away when it crosses the zenith, but over 2,000 km away near the horizon. It was around 45 degrees altitude when the image was captured. Regardless, based on the 109 m length of the truss from Wikipedia and the 510 km distance reported on Legault's web page, the ISS should subtend about 0.74 arc-minutes in the picture. Measuring the image on my computer screen, it was about 4.5 mm along the truss of the ISS and 190 mm across the sun. Using a solar diameter of 32.5 arc-minutes for January 4th (from USNO software), my crude screen measurements yield a similar 0.77 arc-minutes for the ISS.

Joe Stieber

biddie67 wrote:Kudos to Thierry Legault - what a great picture!! I'm amazed at the planning, calculations, timing that had to go into getting this photo! The clarity is wonderful!

But I'm curious - 1/5000 second is beyond human reflexes (at least it is beyond mine) - is this photo taken with some kind of ultra-high-speed video camera and then a specific frame selected for display?

The 1/5000 refers to the shutter speed of the camera, or the length of time the shutter is open to allow light to pass. It is not a matter of reflexes,. The photographer selects when to start the shutter process, but the camera operates at the selected shutter speed. In all likelihood, the photographer was using a multiple-shot sequence. Holding down the shutter button creates a sequence of images. Ah, the wonders of modern technolocgy...

Nice photo Thierry

biddie67 wrote:But I'm curious - 1/5000 second is beyond human reflexes (at least it is beyond mine) - is this photo taken with some kind of ultra-high-speed video camera and then a specific frame selected for display?

It was taken with an ordinary DSLR. The shutter time was 1/5000 of a second, but the photographer had nearly a second while the ISS was crossing the Sun to actually push the button and make that exposure. That still requires good reflexes, but nothing superhuman!

Anyone notice a wave in the surface of the sun along the right side of the photo?

Chris Peterson wrote:

Dan Schroeder wrote:Stupid question: Why is the sun yellow in this photo and so many others?

The Sun is yellow when viewed directly (with sufficient filtering to avoid saturation). How yellow it appears depends on the type of filter used. A very common type of metal coated glass filter gives an even stronger yellow cast than the Sun by itself has. And finally, many imagers simply prefer to add yellow or orange to make what would otherwise be a nearly B&W image more colorful.

No, the sun isn't yellow. It's white with a barely perceptible yellowish (or orangish) tint. So the yellow in the photo must be a result of either the filter or some kind of post-processing or both. I'm wondering which it is.

Dan Schroeder wrote:No, the sun isn't yellow. It's white with a barely perceptible yellowish (or orangish) tint.

Exactly. The Sun is yellow. A low saturation yellow is still yellow.

So the yellow in the photo must be a result of either the filter or some kind of post-processing or both. I'm wondering which it is.

The more saturated yellow could be the result of either, as you say. I don't know which. Legault's site says he uses a Baader helioscope, but I don't know what that is. Baader makes a solar attenuation film that is very neutral, but they also make some front aperture energy rejection filters that are not.

jman wrote:

zorro wrote:Does anyone else think the International Space Station looks like the Canadian flag?

Maybe an omen - Canada vs Russia hockey game's today? Go Team ISS!

First thing I thought - Who planted the Canadian flag on the sun? - Superb Photo.