Lightening keeps throwing up new
physics. That these reactions are so
apparent also suggests that we have a lot more room in terms of experimental
equipment than perhaps was thought.
There is a lot more going on than
can be modeled with simple electron flow which I think has been the obvious
assumption. Particles are also been torn
apart and reassembled. It has challenged
us forever.
Anyway, this is our surprise for
the week that defied prediction.
Antimatter caught streaming from thunderstorms on Earth
By Jason PalmerScience and technology reporter, BBC News, Seattle
11 January 2011 Last updated at 03:34 ET
Electrons racing up electric field lines give rise to light, then
particles, then light
A space telescope has accidentally spotted thunderstorms on Earth
producing beams of antimatter.
Such storms have long been known to give rise to fleeting sparks of
light called terrestrial gamma-ray flashes.
But results from the Fermi telescope show they also give out streams of
electrons and their antimatter counterparts, positrons.
The surprise result was presented by researchers at the American Astronomical Society meeting in
the US
It deepens a mystery about terrestrial gamma-ray flashes, or TGFs -
sparks of light that are estimated to occur 500 times a day in thunderstorms on
Earth. They are a complex interplay of light and matter whose origin is poorly
understood.
Thunderstorms are known to create tremendously high electric fields -
evidenced by lightning strikes.
Electrons in storm regions are accelerated by the fields, reaching
speeds near that of light and emitting high-energy light rays - gamma rays - as
they are deflected by atoms and molecules they encounter.
These flashes are intense - for a thousandth of a second, they can produce
as many charged particles from one flash as are passing through the entire
Earth's atmosphere from all other processes.
Scaling down
The Fermi space telescope is designed to capture gamma rays from all
corners of the cosmos, and sports specific detectors for short bursts of gamma
rays that both distant objects and TGFs can produce.
“Start Quote
I think this is one of the most exciting discoveries in the geosciences
in quite a long time”
"One of the great things about the Gamma-ray Burst Monitor is that
it detects flashes of gamma rays all across the cosmic scale," explained
Julie McEnery, Fermi project scientist at Nasa.
"We see gamma-ray bursts, one of the most distant phenomena we
know about in the Universe, we see bursts from soft gamma-ray repeaters in our
galaxy, flashes of gamma rays from solar flares, our solar neighbourhood - and
now we're also seeing gamma rays from thunderstorms right here on Earth,"
she told BBC News.
Since Fermi launched in mid-2008, the Gamma-ray Burst Monitor (GBM) has
spotted 130 TGFs, picking up on the gamma rays in low Earth orbit as storms
came within its scope.
But within that gamma-ray data lies an
even more interesting result described at the meeting by Dr McEnery
and her collaborators Michael Briggs of the University of Alabama Huntsville
and Joseph Dwyer of the Florida Institute of Technology.
"We expected to see TGFs; they had been seen by the GBM's
predecessor," Dr McEnery explained.
"But what absolutely intrigues us is the discovery that TGFs
produce not just gamma rays but also produce positrons, the antimatter
equivalent to electrons."
When gamma rays pass near the nuclei of atoms, they can turn their
energy into two particles: an electron-positron pair.
Because electrons and positrons are charged, they align along the
Earth's magnetic field lines and can travel vast distances, gathered into
tightly focused beams of matter and antimatter heading in opposite directions.
Gamma rays (purple) can turn into focused matter/antimatter beams
(yellow)
The dance of light and matter continues when positrons encounter
electrons again; they recombine and produce a flash of light of a precise and
characteristic colour.
It is this colour of light, picked up by the Fermi's GBM, that is a
giveaway that antimatter has been produced.
The magnetic field can transport the particles vast distances before
this characteristic flash, and one of the Fermi detections was from a storm
that was happening completely beyond the horizon.
The results will be published in the journal Geophysical Research
Letters.
Steven Cummer, an atmospheric electricity researcher from Duke
University in North Carolina, called the find "truly amazing".
"I think this is one of the most exciting discoveries in the
geosciences in quite a long time - the idea that any planet has thunderstorms
that can create antimatter and then launch it into space in narrow beams that
can be detected by orbiting spacecraft to me sounds like something straight out
of science fiction," he said.
"It has some very important implications for our understanding of
lightning itself. We don't really understand a lot of the detail about how
lightning works. It's a little bit premature to say what the implications of
this are going to be going forward, but I'm very confident this is an important
piece of the puzzle."
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