The sun's corona -- its wispy outer atmosphere
-- has long befuddled scientists.
The sun's surface is 5500 degrees Celsius.
Yet temperatures in the corona, much farther out,
soar to more than a million degrees.
NASA is about to launch a mission not only
to study the corona, but fly into it.
After the Parker Solar Probe launches in August,
it will sidle right up to the sun and spend
the next 6 years conducting 24 flybys
through its scorching corona.
Its closest pass will bring it 10 times closer to the sun
than Mercury's orbit, shattering previous records.
To protect delicate scientific instruments
from the immense heat, the probe is equipped
with a shield made of carbon foam,
similar to the materials that protected
the nose cone of the Space Shuttle.
The Parker probe will repeatedly plunge
into the sun's corona, beaming back measurements
of the tangled net of magnetic fields that shape it.
Most scientists think that the sun's magnetic fields
are responsible for heating the corona,
by somehow transferring energy from a
bubbling cauldron of plasma at the sun's surface.
In one theory, the magnetic field lines that protrude
from the sun move around and get tangled up.
When the field lines suddenly snap into
a more stable arrangement
in a process called magnetic reconnection,
vast amounts of energy are released
into the surrounding plasma of the corona.
The process could also be happening on a
much smaller scale,
with "nanoflares" constantly going off,
each as powerful as a 50-megaton hydrogen bomb
A second theory suggests that the
motion of the bubbling plasma cells on the sun's
surface excites waves in the magnetic
field lines that course outward.
The wiggling of the field lines heats nearby particles.
Researchers hope that Parker will also help
explain another conundrum - how plasma particles
in the solar wind escape into the solar system.
The magnetic field in the sun's corona
has a tight hold on charged particles, but somewhere
at the edge of the corona, they break free
of the sun's gravity, rocketing out into
the solar system at hundreds of kilometers per second.
These particles should slow down and cool off
the farther away they get from the sun,
but they don't --
they're propelled forward by some unknown energy.
By recording the small-scale physics
of the plasma it flies through, the Parker probe
will pinpoint where the wind takes flight
and narrow the possible mechanisms that could launch it.
Understanding the solar wind could help us
better predict dangerous solar storms, launched
by extreme events called coronal mass ejections.
In these storms, the solar wind overpowers
the shield of the Earth's magnetic field,
potentially crippling satellites and electrical grids.
The Parker Solar Probe's future is
definitely going to be bright --
good thing it has some shades.
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