Astro Bob A look at celestial happenings in the Northland and beyond Bob King View my profile Click here to view previous posts or additional resources

Flying seeds and Jovian gas bags

A 12-minute time exposure of the moon reminds me of a glowing test tube. The earthlit portion of the moon is at upper left. The star Delta in Gemini makes its own trail alongside the moon. Details: 200mm lens at f/16, ISO 100. Photo: Bob King

It's fun to try something different. Instead of a quick snap of the crater-crusted crescent moon through the telescope, why not a 10-minute exposure with a telephoto lens? Notice how smoothly the moon slides downward to the right (west) because of Earth's rotation on its axis during the lengthy time exposure.

What looks like the back of someone's head against the starry sky is really the top of a power pole. The myriad flecks are poplar seeds born aloft by tiny attached hairs. Look around the head for the faint arcs of rainbow colors. Details: 400mm lens at f/11. Photo: Bob King

Poplar tree and dandelion seeds have been unleashed in the Duluth area this week. Everywhere you turn, there's white fluff in the air. Reach you hand up to block the sun and if your eyes can stand the glare of blue-white sky, you'll see bazillions of tiny flecks a-flying. When I took the photo above, I was very careful to hide the sun behind a power pole. I like my eyes and hope to use them for the rest of my life. A close-up look at an individual poplar seed (left) shows it to be very tiny and attached to a hairlike tuft of fuzz to aid in flight.

Besides the seed fluff, the picture recorded something I wasn't aware of at the time -- a remarkable series of concentric arcs of color surrounding the sun and no doubt caused by diffraction of light by the tiny hairs protruding from the seeds. These same colors stand out in the close-up photo, too. Light is always getting sliced and diced by objects and media. In this situation, as rays of light pass around the hairy obstacles they interfere with one another like two overlapping expanding wave circles in a pond. Some of the waves reinforce each another and others cancel out. The end result is a series of colored fringes or rings around the light source, in this case the sun.

When I see the floating seeds I'm reminded of a 1976 paper written by the late planetary scientist and astronomy popularizer Carl Sagan and physicist Edwin Salpeter. They wrote of the possibility of life in the extensive atmosphere of Jupiter. At the cloudtops the temperature is more than 200 below zero but hits 70 degrees some hundreds of kilometers below where the pressure is 10 times as great as on Earth. There may even be water vapor clouds at that depth. Since Jupiter has no solid surface, if life evolved, it would be strictly airborne. Jupiter's "surface" lies tens of thousands miles further below and would be hellishly hot and under tremendous pressure from all the material that lies above it.

Jupiter's cloudtops are composed of ammonia ice crystals driven into stripes and swirls by powerful winds. Beneath these temperatures are warmer and perhaps conducive to life. Credit: NASA

Sagan and Salpeter wrote of the potential for huge, gas-bag like organisms that would breath in Jupiter's air and pump it back out, propelling themselves around the planet like extraterrestrial squid. Jupiter has plenty of the right stuff for the building blocks of life to form. Ammonia, water, methane and hydrogen are found in abundance. Under the influence of ultraviolet radiation from the sun, heat from the planet's interior and lighting, these simple materials can be transformed into amino acids, sugars and fats. This seemingly unlikely possibility was demonstrated back in 1952 in the famous Miller-Urey experiment.

The bacterium Deinococcus radiodurans (above), nicknamed "Conan the Bacterium", is extremely resistant to radiation, ultraviolet light and desiccation.

So is Jupiter's atmosphere busy building life? While none has yet to be found, you have to start somewhere and amino acids play a key role in all living things. Our bodies are composed of proteins built of amino acids under the direction of DNA. Perhaps bacterial life (right) might be a better fit for Jupiter. Something microscopic and durable. We know that bacteria thrive in the most extreme environments found on Earth. Toss 'em in boiling water and shoot beams of radiation at 'em and they come back wanting more.

It will probably be a long time before a probe is sent to the Jove to search for potential life. In the meantime we can watch the fluff go by and imagine what could be.

Posted by: rking@duluthnews.com on 5/20/2010 at 1:01 PM | Comments (0) | Permalink | Edit

Tags: daily updates, astro bob, blogs, life, moon, poplar, dandelion, seeds, diffraction, jupiter, bacteria, sagan