Solar Flares
Solar flares are huge explosions of energy from the
Sun. They may also be known as solar prominences or, in some circumstances,
coronal mass ejections (CME). The energy contained inside a solar flare is
immense, ten million times more powerful than a hydrogen bomb. They produce
huge levels of heat and light, throwing out radiation and particles from the
Sun.
The energy that is required for a solar flare to be produced can take days,
even weeks, to build up. However, once the energy is released, it is over within
minutes. The blast of energy in a solar flare is so powerful that it can take
minutes for it to travel from the Sun to Earth - that's a journey of 150 million
kilometres (93 million miles). And once it reaches Earth, it can cause all kinds
of chaos. Yep, they can mess up your television reception and phone signal,
amongst other things.
What causes Solar Flares?
Solar flares are caused by the same process that produces sunspots. Sunspots are areas of intense magnetic activity which prevents some of the Sun's energy, such as heat, from reaching the Sun's visible surface (its photosphere). Therefore sunspots are cooler than other regions of the Sun and are also darker. However, although the Sun's energy is prevented from reaching the Sun's surface in sunspots, it builds up in areas nearby. Eventually, this energy builds up so much that it blasts out of the Sun and into space with such power and force that it produces a solar flare. The Sun goes through an eleven year period of activity. At its least active - during solar minimum - there are very few, if any, sunspots and their related solar flares. However, during solar maximum, the Sun is at its most active, and spottiest, and sends out flares aplenty. On an typical active day, the Sun will produce several flares.
Solar Wind and the effects of Solar Flares
As we know, the Sun produces heat and light, and is
what keeps Earth warm and, um, light. Heat and light are examples of
electromagnetic radiation. The Sun continually pumps out radiation and charged particles of
electrons and protons, sending them across the solar system and into space by a
process known as the solar wind. The
solar system is said to end at the point where the solar wind is no longer able
to push the particles any further. This point known as the heliopause and is many billions of miles further
away than the most distant known planets.
As the solar wind passes the objects in the solar system, it interacts with them
in the several ways. The solar wind carries the Sun's heat (thermal radiation)
and light to Earth. It also carries invisible radiation, such as ultraviolet (UV)
light, to Earth. UV light is what causes people to tan, or if exposed to it for too
long, burn. Excessive exposure to ultraviolet light can cause serious illnesses.
Ultraviolet light is an example of the dangerous radiation that the Sun
produces. In fact, Earth ozone layer, about 20 to 40 kilometres (13 to 25
miles) above the
surface, absorbs about 98% of ultraviolet light, meaning that
only a small percentage of it actually reaches the surface. This is just one
example of how Earth protects itself from the dangers of the Sun. The Sun
produces other kinds of radiation, with different effects, and
Earth deals with
them in different ways, even to the point of producing its very own light show
just to show off. When solar flares occur, they intensify the effects of the
solar wind, as they pump additional levels of the sun's energy - radiation and
particles - into space. This kind of intensified activity is known as a solar
storm.
As an example, the Sun produces electromagnetic radio waves and microwaves. On
Earth, certain technological items also produce these kinds of waves as a way of
sending signals. These include television and radio transmitters, mobile/cell phone masts and satellite dishes. Like the Sun,
Earth also
has a magnetic field. Usually when the electromagnetically charged particles from the
Sun reach Earth through the solar wind, Earth's magnetic field repels them.
There ain't gonna be no harmful electromagnetic thingummies gettin' to
Earth, y'hear!? Some of these particles do get stuck in a region surrounding
Earth called
the Van Allen belt, which is an area of intense radiation, and is of concern
when sending astronauts into space. But during a solar storm, when the effects of the solar wind are more
intensified, quite often as the result of increased solar activity (solar
flares) they do get through the Earth magnetic shield and get into
Earth
atmosphere. And that's where the fun begins. Kind of. The electromagnetic radio
waves from the Sun interfere with the electromagnetic waves produced by radio or
television transmitters. This usually reduces the quality of the signal being
received by radios or television sets, making them seem like they need retuning.
Sound may become unclear and crackly, and picture quality may break up or become
grainy or blocky.
When solar flares aren't affecting people's enjoyment of their favourite
television shows, they produce beautiful light shows. Charged particles sent from the Sun interact with particles in the
Earth atmosphere. They cause the particles to glow and light up the night sky.
This occurrence is known as an aurora and usually occurs in areas near to the
poles, in the far north or far south regions of Earth (northern Scandinavia,
Greenland, Alaska, Canada, southern New Zealand and Australia, South America and
Antarctica). An aurora in the northern hemisphere is called the aurora borealis,
or the northern lights, and in the sourthern hemisphere, it is called the aurora
australis, or the southern lights. During particularly strong solar storms when
the sun is in the solar maximum part of its solar cycle, an aurora may be seen
further away from the poles. The video below shows the aurora australis filmed
from Antarctica.
