For the first time, a set of equations that can help describe waves in the solar wind known as Alfven waves was created
by Aaron Roberts, a space scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.,
"Since the 1970s, scientists have known that movement in the solar wind often has the characteristics of a kind of
wave called an Alfvén wave," says Aaron Roberts, a space scientist at Goddard. "Imagine you have a jump rope and you
wiggle one end so that it sends waves down the rope. Alfvén waves are similar, but the moving rope is a magnetic field line itself."
Click on image to enlarge
A constant stream of particles and electromagnetic waves streams from the sun toward Earth, which is surrounded by a protective bubble called the magnetosphere. A scientist at NASA Goddard has recently devised,
for the first time, a set of equations that can help describe waves in the solar wind known as Alfven waves. Credit: European Space Agency (ESA)
The Alfvén waves in this case tended to have great consistency in height -- or amplitude, which is the common term
when talking about waves -- but they are random in direction. You might think of it like a jump rope twirling,
always the same distance from center, but nonetheless able to be in many places in space.
Another way scientists have envisioned the waves is as a "random walk on a sphere." Again, always the same distance
from a given center, but with a variable placement.
Such metaphorical descriptions are based on what instruments in space have, in fact, observed when they see magnetic
waves go by in the solar wind. But it turns out that the equations to describe this kind of movement -- equations
necessary to advance scientific models of the entire system -- were not easily found.
"The puzzle has been to figure out why the amplitude is so constant," says Roberts.
"But it's been very difficult to find equations that satisfy all the characteristics of the magnetic field."
Similar waves are, in fact, seen in light, known as polarized waves. But magnetic fields have additional constraints
on what shapes and configurations are even possible.
Roberts found a way to overlap numerous waves of different wavelengths in such a way that they ultimately made
the variation in amplitude as small as possible.
To his surprise, the equations Roberts devised matched what was observed more closely than he'd expected.
Not only did the equations show waves of constant amplitude, but they also showed occasional random jumps and
sharp changes -- an unexplained feature seen in the observations themselves.
"Overlapping the waves in this way gives us a way of writing down equations that we didn't have before," says Roberts.
"It also has this nice consequence that it is more realistic than we expected, since it shows discontinuities
we actually see in the wind. This is important for simulations and models where we want to start with initial
conditions that are as close to the observed solar wind as we can get."
Of course, having an equation doesn't yet tell us the reason why the waves in the solar wind are shaped in this way.
Nonetheless, equations that describe how the waves move open the door to increasingly accurate simulations that may
well help explain such causes.
Lake In France Turns Red
This year, we have encountered the color red in places where we don't expect to see it. A while back the strange appearance
of Azov Sea stunned residents who saw how the water had turned red. The red rocks in China have also puzzled scientists for a long time.
Now, a lake in Southern France has also suddenly turned red.
An Incredible Geological Phenomena
Earth is an amazing planet and our nature is full of wonders. We have previously written about incredible singing plants.
This time we would like to focus our readers' attention on another amazing geological phenomena, namely so-called growing stones.
It is difficult to image that stones can really grow, but these stones seem to be alive!
Yangtze River In China Turns Red
We have seen on a couple of occassions how lakes and seas have suddenly turned red.
In August a lake in Southern France unexpectedly changed color and shortly before that the strange appearance of
Azov Sea stunned residents who saw how the water had turned red....