Science Bulletins: Space Weather—Storms from the Sun


The sun is often referred to in astronomical
texts as a garden-variety star, which is okay because it is a fairly common type, although
I object to it sometimes because “garden” sort of implies “uninteresting.” We can have energy from the sun that affects our communication systems. It can also affect
satellites, space missions, and can cause problems with power grids and things like
that. This is Kitt Peak National Observatory and
the National Solar Observatory. This is a pretty sunny site. We are in the Southwest,
in the middle of a desert at a fairly high altitude—about seven thousand feet—so
we’re above much of the atmospheric haze that lies down in the lower desert.
This is called the solar vacuum telescope. It’s a special telescope to observe only
the sun, making a special use of mirrors to produce a stationary image inside an observing
room. The actual observing apparatus then consists of a spectromagnetograph, which is
a special instrument designed to look at the sun’s magnetic field. The magnetic field
is probably the fundamental physical mechanism which controls the outer solar atmosphere.
It’s because it varies and changes that particles become accelerated and they’re directed towards
the earth. The areas of strong field are probably here,
here, here. This region in particular is an example of an active region. It’s a region
that is likely to erupt, where large volumes of the sun simply are ejected out into interplanetary
space and that is at the heart of space weather. Space weather starts at the sun and the sun’s
atmosphere explodes off of the sun and it flows out into interplanetary space in all
directions at about a million miles per hour. And then, when that flowing solar wind impacts
the earth’s magnetosphere, hits the earth’s magnetic field, some of the solar wind particles
and some of that flowing energy get trapped, and when the energy is released, it causes
enormous acceleration of particles that give us the radiation belts that impact astronauts
and impact satellites. It also generates the aurora borealis that we see, and it drives
large electrical currents in the high latitude ionosphere that can impact power transmission
on the ground, pipelines, communications, those sorts of things. And then on top of
that, the sun occasionally blasts off these large coronal mass ejections, and when one
of those impacts the magnetosphere, it is just like hitting an already stressed system
with a very large wallop and that causes some of the largest space weather activity that
we see. Good morning, Space Weather Operations. This
is Ken. The largest flare was in M2. That’s an incredibly
impressive region. All solar activity does not hit the earth–CMEs, solar flares. It
depends where they originated from on the sun and where we’re located in space. Something
that’s located in the middle of the sun, from there heading straight toward the earth would
be the most likely direct hit. Right here, that’s the one that has been giving
us most of the activity. The data that the Space Environment Center
uses is a collection of ground-based and space-based instruments. So a forecast made moderate to
high M class flares are likely. Our forecasts, our information, our alerts and watches and
warnings go out to a variety of customers. Power companies receive our information. Operation
centers that are operating satellites. Airlines use our information for radio blackouts. Geologists
use our information for checking their instruments before they drill. Our forecasts on the short
term are not bad at all, they’re actually pretty accurate. Long term, even with the
weather forecasts, it’s difficult to say things three to seven days out.
I think the day will come when space weather reports become mainstream in our society,
in our news broadcasts and our newspapers, because we’re certainly using space more and
more and I think we will continue to, and we’re relying on it more and more for our
economy and for our standard of living. And as we use space and rely on space, space weather
information is likely to become more prevalent in our daily lives. Space Weather Operations, this is Gail.

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