Illuminating the Sun
BY BEN GILLILAND
|Considering how important it is to life on Earth - without it there would
be none - we know surprisingly little about the mechanism that drives the
workings of the star we call 'Sun'. Launched in September last year, the
Hinode (Japanese for 'sunrise') spacecraft has three powerful telescopes
trained on the Sun.
Some of the first results from the mission, led by the Japan Aerospace
Exploration Agency, are published today as a series of studies in the journal
The spacecraft can view the Sun in visible, X-ray and ultraviolet wavelengths,
allowing researchers to capture high-resolution images and video of its
structures and magnetic fields. One of the biggest mysteries the craft is
tasked with solving is the so-called 'corona problem'. The Sun's surface
is hot - 5,700ºC (10,300ºF) - but its atmosphere is hotter - a
searing 999,000ºC (1,800,000ºF) plus. Why, or how, this can be
has puzzled scientists for decades. One of the studies has confirmed the
existence of a type of magnetic wave, known as an Alfvén wave, which
ripples through the plasma of the Sun's corona and may heat the corona as
it travels from the Sun. Another has pinpointed a region where plasma is
continually flowing into the upper corona as a possible source of solar wind
- vast clouds of electrically charged particles that can disrupt communication
systems and power grids on Earth.
|We are currently basking in a solar minimum
- a period of low solar activity. However,. over the next few years, the
number of solar flares and eruptions known as coronal mass ejections will
increase until they reach a peak in about 2012.
Scientists are also predicting that this next solar cycle will be the most
intense for 50 years. Such activity produces solar winds that can have drastic
eftects on Earth, disrupting satellites, communications and even power grids.As
such, understanding mechanisms of the Sun is increasingly important.
Crucial to this research is Hinode's X-ray telescope which has already provided
a now look at the less powerful cousins of these solar eruptions: X-ray jets.
Both X-ray jets and solar flares are the result of 'magnetic reconnection'
- areas where magnetic field lines of opposing polarity meet and annihilate,
releasing energy. This energy propels electrically charged gas or plasma
out into the solar system and towards Earth. Previously research had looked
at only a few X-ray jets. Hinode has already observed an average of 240 jets