“Once in a Civilization” Comet to Zip past Earth Next Year


By Michael Moyer, October 5, 2012


 

Comet Hartley 2

Close, but not this close

As it flares out of the distant Oort Cloud, the newly discovered cometC/2012 S1 (ISON) appears to be heading on a trajectory that could make for one of the most spectacular night-sky events in living memory. Why is this comet expected to be so unique? Two reasons:

Astronomers predict that the comet will pass just 1.16 million miles from the Sun as it swings around its perihelion, or closest approach. (This may seem like a lot, but remember—the Sun is big. If we were to scale the Sun down to the size of Earth, the comet would pass well within the orbits of dozens of satellites.) The close approach will melt enormous amounts of the comet’s ice, releasing dust and gas and forming what should be a magnificent tail.

After it loops around the Sun and forms this tail, the comet should then pass relatively close to Earth—not near enough to cause any worry, but close enough to put on a great show. Viewers in the Northern Hemisphere will get the best view as the comet blooms in the weeks approaching Christmas 2013. The comet could growas bright as the full moon.

Of course, comets have a habit of not living up to expectations. This one could be sucked into the Sun during its close approach, or not grow as much of a tail as astronomers hope.

But that hasn’t dampened enthusiasm for what Astronomy Now is awkwardly calling “a once-in-a-civilisation’s-lifetime” event. The comet expert John E. Bortle is already comparing ISON with the Great Comet of 1680, which, according to contemporary accounts, caused the people of New York’s Manhattan Island to be “overcome with terror at a sight in the heavens such as has seldom greeted human eyes….  In the province of New York a day of fasting and humiliation was appointed, in order that the wrath of God might be assuaged.”

We can only hope for such a show.

 

Image of comet Hartley 2 courtesy NASA/JPL-Caltech/UMD

Sunflowers inspire efficient solar power


By Emily Eggleston    |  Sun, 09/30/2012 – 4:21pm

In August, UW-Madison researcher Hongrui Jiang published his design for solar panels that act like sunflowers, tracking the sun’s movement throughout the day. Jiang, a professor in computer and electrical engineering, used nanotechnology to design a system that helps the panels move by reacting to the warmth of the sun’s rays, rather than using a motor and global positioning system (GPS) as many solar tracking panels do. Read Jiang’s answers to Madison Commons’ questions about how the new solar technology works and what else he is doing with nanotechnology.

 

MC: Why are you interested in solar technology?

HJ: Renewable energy is very important right now because we are running out of fossil fuels. We have to look for other possible sources of energy. Solar energy is very promising because pretty much everywhere has sunlight, not like wind or geothermal, and it lasts forever.

MC: Describe the work you do in patterning solar panel movement after sunflowers.

HJ: The basic idea is solar-tracking. If you can have a solar panel follow the sun during the day, you’ll have more interception of light, and therefore more electricity. The idea is very simple and done by many plants in nature. Sunflower is one example, a buttercup flower is another. The idea is very simple but not easy to realizing it with solar plans is complicated because you have to mimic complex biochemical processes.

MC: Don’t some solar panels already track the sun’s movment?

HJ: In the solar tracking systems available now, most use GPS with motors. They are active mechanical systems to orient towards sun. Active systems are great but mechanics consume energy themselves. The purpose is to get as much electricity as possible. Our system is passive, it doesn’t consume electricity to drive solar tracking. Also, it is very hard for active systems to realize full range tracking, sunrise to sunset. Ours does.

MC: How does the passive system of solar tracking work?

HJ: We needed a material that would respond to natural sunlight, whole spectrum light of all wavelengths. has to be sensitive enough. Some materials are responsive to strong light like lasers, but we need the solar panel to be responsive to whatever intensity the sunlight is at. Sunlight hits a mirror which projects light onto actuator holding carbon nanotubes. When the nanotubes warm they contract, causing the panel to shift toward the contracted nanotubes.

MC: You use nanotechnology in your some of your other research. What else do you do on the super tiny nano scale?

HJ: My expertise in the microsystems and microscale optics. I’m working on making a tunable liquid contact lens that adds extra focusing power. When you are getting older the muscle in your eye starts to lose power and it becomes harder and harder for you to see up close so people wear bi- or trifocals. This contact lens autofocuses, basically like the point and shoot cameras that you use. It’s not just a lens, it’s a whole spectrum of gadgets [with] circuits and everything, but it has to be flexible. You need an energy source to provide electricity for the circuits. Right now we’re trying to harvest and store solar energy right in the lens. It’s a very challenging idea and we’re off to a good start.