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Scientists Finally Confirm How Sun Produces Light

by ScienceDave | August 20, 2007 at 01:35 pm

2184 views | 65 Recommendations | 9 comments

It seems a bit far fetched - humanity has come a long way, yet one of the basic questions proto-Homo sapiens dealt with for millenia, "Where does sunlight come from?", has only now been confirmed by scientists at Princeton University.

The Princeton scientist's discovery was made possible by the Gran Sasso National Laboratory, 120 km from Rome, Italy. The laboratory is the largest of its kind, and specifically designed for investigating how subatomic particles work their 'magic'.

That's also why the laboratory had to be built in a mountain bearing the same name as the lab itself - this geographical seclusion drops any background radiation flying around the universe from interrupting their 15 experiments currently underway.

The Borexino experiment, led by the Princeton scientists, has sought out to study neutrinos - subatomic particles responsible for so-called 'weak-nuclear forces', one of the fundamental quantum forces keeping our universe cohesive and stuck together. However, successfuly detecting neutrinos sing only water, according to the Borexino website is equivalent to requiring width of water equivalent to the diameter of 100,000 of our solar systems.

However, they make use of "scintilation liquid" - a special mixture of chemicals that produces a flash of light when neutrinos bombard it. These flashes are then measured and enhanced by photo-multiplying tubes surrounding the sphere of liquid scintillation.

The answer lies in the fact that neutrino absorption is a statistical process: a few neutrinos (very few!) can interact even in a small amount of material. They key to neutrino detection is in fact having very many neutrinos impinging on your experimental setup...

... Therefore, in spite of the elusiveness of this particle, experiments are being made to determine its properties. An important experimental feature is a big detector mass, so that many targets are available for neutrinos to interact. BOREXINO is no exception in this sense. The detector features 1300 tons of scintillator and 2400 tons of water.

So what exactly have the Princeton scientists discovered about our sun using this mountain-sized instrument? Well, the sun is actually our closest source of neutrinos - created at its core during the plethora of nuclear reactions that take place to convert hydrogen into helium. This process was hypothesized to require the element beryllium, but it has not been possible to determine whether this was true - until now.

"Our observations essentially confirm that we understand how the sun shines," said Frank Calaprice, a professor of physics and principal investigator of the Princeton team. "Physicists have had theories regarding the nuclear reactions within the sun for years, but direct observations have remained elusive. Now we understand these reactions much better."...

..."This experiment is an important step along the way toward understanding the details of neutrino physics using neutrinos from the sun," said physicist Morgan Wascko, co-spokesman for SciBooNE neutrino experiment at Fermi National Accelerator Laboratory. "Using these particles to observe the sun is important because they give us a lot of information about the way the universe functions, because it's full of stars."

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Jordan Yerman

flagged this story as Good Stuff

at 13:49 on August 20th, 2007

Awesome.

kkaefer

flagged this story as Good Stuff

at 14:06 on August 20th, 2007

Thanks for sharing this very interesting story!

Zlender

flagged this story as Good Stuff

at 14:34 on August 20th, 2007

nouseforadave, thanks. This is amazing stuff.

enathu

at 21:07 on August 20th, 2007

nouseforadave, this is an interesting stuff..

JaredM

flagged this story as Good Stuff

at 06:42 on August 21st, 2007

Here I thought it would be another grass is green, water is wet article from the Research Institute of the Bleeding Obvious. I was pleasently surpised it is an very interesting read. Good Stuff.

bill field (not verified)

at 16:07 on July 27th, 2008

Very interesting, but can anyone tell me the frequency of sunlight?

MPL (not verified)

at 07:02 on August 6th, 2008

I understand what neutrino detectors are and how they work, and they are cool and all, but what in the world is the title and opening paragraph about?? You make it sound like scientists didn't know how the sun produces light. Of course they did! Studying neutrinos doesn't specifically give us any new information on the sun's emission of visible light, though the 2 are of course interconnected...

You even include this quote: "Our observations essentially confirm that we understand how the sun shines." These observations provide more detail, but that title is extremely misleading. I don't think there has been any doubt in recent decades that the Sun shines by nuclear fusion.