Galileo's Epiphany

Galileo could not deny what he saw through his new telescope. These were not stars, as he had first thought when he discovered the moons of Jupiter on January 7, 1610. The little pinpoints of light, arrayed in a straight line near the large planet, moved. Stars don't do that. Even in the space of 30 minutes, one could observe changes in position relative to the planet and to each other, as I witnessed and photographed on Tuesday. (Please pardon the third shot's quality; I was shooting through a thick smoky haze.)

On January 10, 1610, Galileo observed that one of the objects disappeared behind Jupiter, then re-emerged later. He concluded that these objects must be moons orbiting Jupiter. It was a mini "solar system," in plain view of anyone who cared to observe. Eventually, Galileo even worked out their orbits and could predict when and where the Jovian moons would show up.

This was an earthshaking finding. According to http://en.wikipedia.org/wiki/Galileo: A planet with smaller planets orbiting it did not conform to the principles of Aristotelian Cosmology, which held that all heavenly bodies should circle the Earth, and many astronomers and philosophers initially refused to believe that Galileo could have discovered such a thing. His observations were confirmed by the observatory of Christopher Clavius and he received a hero's welcome when he visited Rome in 1611.

However, Galileo's "hero" status was short-lived: Galileo's championing of Copernicanism was controversial within his lifetime, when a large majority of philosophers and astronomers still subscribed (at least outwardly) to the geocentric view that the Earth is at the centre of the universe. After 1610, when he began supporting heliocentrism publicly, he met with bitter opposition from some philosophers and clerics, and two of the latter eventually denounced him to the Roman Inquisition early in 1615. Although he was cleared of any offence at that time, the Catholic Church nevertheless condemned heliocentrism as "false and contrary to Scripture" in February 1616, and Galileo was warned to abandon his support for it—which he promised to do. When he later defended his views in his most famous work, Dialogue Concerning the Two Chief World Systems, published in 1632, he was tried by the Inquisition, found "vehemently suspect of heresy," forced to recant, and spent the rest of his life under house arrest.

At issue was the belief that the Bible delares the earth to be the center of the solar system: Psalm 93:1, Psalm 96:10, and 1 Chronicles 16:30 include (depending on translation) text stating that "the world is firmly established, it cannot be moved." In the same tradition, Psalm 104:5 says, "the LORD set the earth on its foundations; it can never be moved." Further, Ecclesiastes 1:5 states that "And the sun rises and sets and returns to its place" etc.

Of course, in hindsight all Christians now understand that these passages were written from the perspective of an observer; they do not address the astronomical relationship between the sun and the earth.

A friend of mine who is a pastor in California put it well: Careful observation of the natural world can cause Christians to go back to the Bible and reexamine whether it really teaches what we have understood it to say in the past.

Liquid HDR

On a recent trip to Idaho, we took a walk that crossed the Boise River on a footbridge. The photo above is what I saw from the bridge: sunlight glinting off the water's wavelets, a vehicle bridge with cars, and bright picturesque clouds in the sky. Surrounding the scene was late-summer green foliage, gently moving in the breeze.

Here was the camera's best effort to capture the scene in one photo:



The sun reflections were blown out, yet the back-lit bridge was underexposed. The overexposed sky lost cloud detail, but the trees were darkened by their underexposure.

Of course, the first photo is a High Dynamic Range picture, which rescued the scene. I have discussed HDR in numerous postings in this blog, but there has always been a problem: motion. In one posting ("Dynamic World Thwarts Dynamic Range Photography"), I lament the need for multiple photos to compile an HDR shot: "Until cameras start getting built with High Dynamic Range sensors to capture contrasty motion scenes in one shot, much of the dynamic world will remain out of reach of HDR photography."

Last week, much to my chagrin, I realized that the "until" time has already arrived for many motion HDR shots -- without the need to buy new equipment. The HDR photo above is an example of that "new" technology, enabling me to capture an High Dynamic Range image from a single instant in time -- a necessary feature for any photo with liquid water, breeze-blown tree leaves, etc.

As you may know, an ordinary JPEG digital photo is composed of data with 24 bits per pixel; 8 for each primary color. So, each color channel must be expressed with an intensity number of 0-127. That significantly limits the dynamic range. Wouldn't it be nice if cameras could capture more dynamic range in each shot?

Well, DSLRs do that very thing. In my case, the Canon 400D captures 36 bits per pixel; 12 for each primary color (0-2047). Then, when it constructs the 24-bit JPEG image to be stored on the memory card, it throws away the "extra" bits after applying color balance, contrast and sharpness parameters. But the original image's data -- all 36 bits -- is still available in the RAW format file, adding one or two stops of dynamic range. Duh. (Why didn't I think of that before?)

That lets me construct a triad of three exposures by "developing" the RAW data into JPEGs that are underexposed, normal, and overexposed. Then HDR software like Photomatix takes it from there.

With this realization, I will be able decide to use HDR after the fact. And, I'm no longer troubled by motion in the scene.

Of course, an extreme case like the Tillamook Air Museum's blimp hanger still needs multiple shots; six in this case, with a 9-stop dynamic range:



But now I can reserve the time-consuming sequence shooting for the situations that truly need them.

Chasing the Space Shuttle

At 12:26p Tuesday, the space shuttle Discovery undocked from the International Space Station (ISS). At 9:20p, the pair presented a graceful duet of brighter-than-Venus dots silently gliding overhead. I guess the ISS didn't want the Shuttle to leave, since the space station appeared to be chasing it across the sky. Of course, the ISS will never catch up; the photograph proves it. The eleven-second trace for the Shuttle is 36% longer than the one for the ISS, vividly showing their relative speeds.

About 30 seconds later, both the ISS and Shuttle disappeared. Here is the trace from the ISS plunge into the darkness of Earth's shadow:



To see it larger, click on the image above. To see it full-size, click here.

The last time I saw the ISS and the Shuttle undocked, I was in downtown Cairo, peering between buildings, hoping my view was somewhat toward the southwest. This time was much better! :-)

Moon-lit Moonless Night

It only happens a few times a century. First it was Callisto, followed by Io. Then, Europa and Ganymede briefly "kissed" before meeting their fate. One-by-one the the four Galilean moons of Jupiter disappeared. The first two went around the back; the second set across the Jovian face. Between 9:43p and 11:28p last night, Jupiter appeared to be moonless.

In the photo above, nothing looks amiss. Our own moon bathes the clouds with light while Jupiter peeks out from an opening in the lower-right. But if Jupiter is magnified, it seems strangely naked:



In comparison, here is how it looked in an earlier post, at the same zoom level:



At that time, all four Galilean moons were quite visible, in contrast to the view yesterday.

Note that the Jovian disk is overexposed to show the moons. In a differently exposed photo from last night, I was able to resolve some markings on the planet itself (more visible here thanks to contrast enhancement and a 2x digital zoom):



Of course, the resolution is not high enough to see the disks of Europa and Ganymede in front of the large planet -- or much of anything else for that matter -- but IMHO it's not bad for an ordinary telephoto lens and photographic tripod.

As a bonus last night, I also captured a fun shot of a baby dragon practicing his puffs. :-)