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Sunday, 17 May 2009


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Congrats to Thierry...his website is overloaded with requests and is currently unaccessible

He photographed two transits - the one you show is the first, with the shuttle at an altitude of 260km, and lasted only 0.3 seconds! I was amazed by his comment about the image: "The thin silhouette confirms that the cargo bay doors were opened." The image has enough resolution to distinguish a 2 meter wide feature at 260km - incredible.

this has been all over the net, but i still cannot see it enough. it's always good to have a reminder of how small even our largest creations are when compared to what exists in nature. gives you a sense of perspective :)

Dear Folks,

Here's the link to Thierry's homepage; worth perusing for all sorts of cool photos (personally, I prefer the ISS against the sun over the current fave).

I haven't had an problem with it loading the last few days, and that's with him having another APOD photo a coupla days back:


pax / Ctein

Nasa Astronomy Picture of the Day, for those who need more of astro photos.


Why is the sun darker around the edges?

Talk about the decisive moment.

I'm not really into this stuff...space travel, the celestial galaxies etc, but I have been looking at this photo for a few days now. I find it as fascinating as almost any photo I have ever seen.

Somehow I knew it would show up here on TOP.

Out of this world man.

Re: John Camp:


@John Camp: The effect is called "limb darkening". The wikipedia page describing it seems to be reasonably accurate from a quick skim. Essentially when you look at the solar limb, you are seeing less deep into the atmosphere than you are at the center of the disc, so it's cooler and therefore redder and dimmer.

Some of Thierry's photography is spectacular, and this transit is certainly no exception.

I saw this on NASA's APOD, too. Plus he got the shuttle and Hubble side-by-side: http://antwrp.gsfc.nasa.gov/apod/ap090516.html

Who says 50mm is good enough for the decisive moment?

Spectacular stuff for sure. It makes my occasional full moon photo look kind of pathetic.

If you love astronomy images, I enthusiastically recommend checking out the Hubble heritage site at

This site contains scores of high resolution images captured by the Hubble orbiting space telescope, some of them greater than a gigabyte in size when saved to your computer. (You have to click through to the "full resolution image" links.) Needless to say, you'll need a broadband connection. One mind-blowing image of the Carina nebula opens at a native resolution of nearly 48x100" at 300 ppi. As you repeatedly click on the "+" icon you just keep seeing more detail in the dust clouds and stars. And the thing is, you could drop our entire solar system into this image, and it would cover about three pixels.
Some of the images of spiral galaxies (M51 is my favorite) are breathtakingly beautiful. I printed this one at 17x24" and have it hanging on my wall; I keep finding myself standing in front of it, staring in slack-jawed astonishment.
Consider yourself warned.

This guy is deserving of all the praise he gets, that is a shot of a lifetime.


next up: the clouds of venus? titan? the gas giants?

Isn't the sun 93 million miles away?

John Camp wrote: "Why is the sun darker around the edges?"

John, this effect is known as Limb Darkening. Here is a technical explanation:


And here is a more layman-friendly version:


Although not quite the same thing as limb darkening, you can see the effect in spheres frontally-lit by reflecting light, too, because there's less light reflecting back off the surface at the "edges" of what you can see. Here's a random example I pulled off the web....



Similar and equally cool are videos of the Space Station taken from the ground. Search a bit...you can also see the ISS transiting the Moon.


It is a fantastic picture, and somehow feels so lonely. This tiny man-made craft with a handful of human beings on board sailing through the vastness of space. It's quite wonderful.

1) WOW! Look how clear the sun is!!! NO SUNSPOTS!

2) Since we're on the topic...

This guy has some really great stuff to help people get started in astrophotography:


He also has an image of ISS against the sun:


The info accompanying the photo is great!

You know, considering the strong backlighting, I think he should have opened up a couple of stops. There's no detail in the spacecraft at all.

Wait a minute! I'm sorry. I thought I was posting to photo.net.

"Isn't the sun 93 million miles away?"

Yes, it is, and the shuttle is only a few hundred. Space is actually pretty close. You could drive there in an afternoon if only you could go straight up.

My 1990 Volvo 240 has enough miles to make it to the Moon. It's just not space-rated.

I think this is a testament to Canon auto-focus technology that it locked on to the correct subject, Atlantis, despite being a small part of the whole frame, and the second object being so much farther away.


I assume you're kidding, but Canon's AF doesn't enter into it when you've got the camera mounted on a telescope.


You could do this in Photoshop...without any need for cropping :)

>>WOW! Look how clear the sun is!!! NO SUNSPOTS!<<

If I didn't know that solar activity was unusually low, I might suggest they'd been cloned out in PS.

And what about those suspicious artifacts around the shuttle silhouette ? :-)

Re: Aizan's "next up: the clouds of venus? titan? the gas giants?", I went so far as to compare the angular diameter of the shuttle in the featured photo (pixel counting relative to the size of the sun in the photo, it's about 25" of arc), because it looked as if it might be comparable in size to some of the planets. It turns out that Saturn subtends 25-30" of arc, Jupiter 30-49", Venus 10-66", depending on relative positions in their orbits (this from "Angular Diameters" on Wikipedia). I didn't post because it gets a little ridiculous. Transit times are about 5 milliseconds and the shadow path on earth is about as wide as the shuttle itself, so it's a real challenge. Starting to take photos 2 seconds before the event and hoping for nice framing isn't going to work! Getting enough light in a short enough exposure to freeze the motion of the shuttle becomes the issue, instead of controlling the backlight. Nooooo!

Mike, I think Steve Bufton is right: the data reported in your post is for a different exposure, taken a day after this one. However, both exposures have identical wicked cool quotients.

Wow! That was a shot I never expected to see unless done as a special effect for a film.

I wonder what a rig like the one shown on his website would run?

Dear Al,

Thierry's using primo gear. His scope's run between $3K and $12K. The CCD camera's $6K. And good mounts are in the same price range as the scopes. So, serious bucks.

BUT... you can do excellent astrophotography for a whole lot less, comparable to what you'd pay for a good DSLR; see the comments in this column:


Mostly, astrophotography's about the skill, not the gear. You could make photos like the one at the top of this page with under $1,000 worth of equipment.

pax / Ctein

One of the nice things about the latest batch of DSLR cameras is their wonderful high ISO performance.
There are a lot of moderately priced scopes out there with equatorial mounts that you could use as a guide.
Learn how to polar align the scope, put a 300 f4 (2.8 would be even better) on the camera and piggyback a 30 second exposure of M42 at about ISO 3200 and you will be amazed.
Heck on a dark night just lock the camera down with a fast prime for a star trails shot. I tried it with a D70 with an old 105 2.5 wide open and got nice color off Orion.
What fun. You don't have to spend the price of a nice car to give astrophotography a try.

You've done it again here Mike. Another mind-boggling, fantastic post. Thank you.

Dear Folks,

What Mike Plews said-- that's how all the astrophotos on my web site were done.

Further comments on 'affordable' options.


This'll run you about $3,300 (the price of a fancy DLSR plus a lens or two). It's everything you need to do pretty serious astrophotography. Definitely NOT the least expensive way to go, but it's a sweet scope and camera. The mount is marginal; you'll need to take care to shield the scope from breezes and vibration. But it's usable

(BTW, I could trim a grand from the price tag by custom picking exactly what would suit my needs.)

As with terrestrial photography, great astrophotography depends more on skill than gear.

pax / Ctein

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