Tuesday, March 13, 2007

NASA - Stereo Eclipse

Just a very quick post, this time from NASA who have released a few images, including a movie, of the Moon transiting the Sun, which were captured as the cameras aboard STEREO-B were being calibrated.

"What an extraordinary view," says Lika Guhathakurta, STEREO Program Scientist at NASA headquarters. The fantastically-colored star is our own sun as STEREO sees it in four wavelengths of extreme ultraviolet light. The black disk is the Moon. "We caught a lunar transit of the sun," she explains.

The purpose of the experiment was to measure the 'dark current' of STEREO-B's CCD detectors. The idea is familiar to amateur astronomers: Point your telescope at something black and see how much 'dark current' trickles out of the CCD. Later, when real astrophotography is taking place, the dark current is subtracted to improve the image.


STEREO-B is one of a pair of spacecraft tasked with imaging the Sun, and is 1 million miles 'back' from STEREO-A, the 'advanced' positioned craft, which allows for offset images to be captured, which are then later combined to produce 3-dimensional images of such events as solar storms.

Of particular interest are coronal mass ejections (CMEs), billion ton clouds of electrified gas hurled into space by explosions on the sun. "STEREO's ability to see these clouds in 3-dimensions will revolutionize our understanding of CMEs and improve our ability to predict when they will hit Earth," she says.

The STEREO mission is still in its early stages. The two spacecraft were launched in Oct. 2006 and reached their stations on either side of Earth in January 2007. Now it's time for check-out and calibration. The first 3D views of solar storms are expected in April.


So hopefully, we'll be back in a month or two hence, gazing at suitably wondrous images of our shining parent star.

In the meantime, it's definitely worth paying the STEREO website a visit, as well as bookmarking it for return visits

2 comments:

DavidD said...

Ah, but isn't the sun merely a large sibling? Maybe it is older in terms of the time it took for all of our planetesimals to come together while solar fusion already had ignited, but that's only like being the oldest pup of a litter.

Our parents were however many supernovas it took to seed the solar system with elements heavier than helium. They're more like insect parents who lay eggs that yield offspring who then never see their parents, because the parents die in the meantime. That may not be disconcerting to insects, but for those of us who didn't know one or more biological parents, it is a strangely compelling mystery on a human scale as well as on a cosmic one. I remember some paper in the nineties by someone who was speculating about the last supernova that triggered the formation of the solar system, based on mapping nearby stars. It wasn't very specific.

So those of us who are fatherless look for father figures. Sol was a traditional choice, but no matter how one photographs it, it's still just a churning ball of hydrogen and helium. It's not the brains behind anything. Then again maybe the universe does it all without a brain in Her head. She needs us to tell Her how beautiful She is, mother, sister, spouse, child, whatever She is. Otherwise She wouldn't know. Maybe She doesn't care which one She is, as long as we love Her.

Tim said...

Hi David, good to hear from you again, loads of good points as usual! Although the Sun is as you say, an incandescent ball of hydrogen and helium, it's still capable of doing us great damage, including potential global extinction, with massive X-class Coronal Mass Ejections and the like. Whereas on the other other hand, this life that we know couldn't exist without it, so in that sense it holds ultimate sway over lives on Earth, with us powerless to intervene or mediate the effects therefrom, and that was more the parental effect I was alluding to.

But I take your point that the Sun obviously doesn't have sentient role in our lives, which in some ways is a shame as it might have then been able to tell some of the former solar cultures of our past not to bother with the blood sacrifice of thousands of hapless humans - just a thought.

Sorry to be so brief but I'm in a mad rush to get a lot of things done by tomorrow as I'm travelling abroad, but once safely at the other end I'll get back to your previous comments of last week, thanks again for commenting, best, Tim

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