Featured Star: Our Sun

Oct 25 2013

When we think of the Sun, we picture a glowing yellow ball in the sky that gives us our sunny days and leaves us during our starry nights. Did you know the Sun is a star? It is our star; it sits at the centre of our solar system and is 150 million kilometres away. 

Like all stars, the sun is a ball of churning, million degree hot plasma generating colossal amounts of energy through nuclear reactions deep in its core. Similar to the Earth, the Sun has an atmosphere, but it consists of very hot gases that extend into space and powers what we call the solar wind. A solar wind is a flow of electrons and protons (the building-blocks of atoms and molecules) from the Sun out through the solar system. When the solar wind reaches the Earth, our planet's magnetic field guides these charged particles around the upper atmosphere. Thankfully this keeps us protected down here on the surface from the harmful radiation it would cause. 

But the Sun can also be a source of explosive energy release, causing eruptions at its surface in the form of solar flares and ejections of plasma. If these happen to be directed at the Earth, the increased amounts of particles in the solar wind can cause negative effects in our atmosphere - this phenomenon is known as "space weather". A classic example of this is the aurora that can sometimes be seen in the night sky, mostly close to the north and south poles. These are fantastic colourful light shows that arise from the interaction of the solar wind with the molecules of oxygen and nitrogen in Earth's atmosphere. 

Nowadays however, modern societies' dependency on technology, requires that we use the atmosphere to bounce signals around the Earth to and from aircrafts and satellites. To this end, it has become increasingly important to understand the dynamics of solar eruptions and their effects on the Earth, in order to develop methods to forecast their occurrence and possible impact time. 

Numerous missions have been launched to provide observations of the Sun. The data collected can be used to study the Suns activity, the solar winds, flares and eruptions. These missions include the NASA & ESA Solar & Heliospheric Observatory (SOHO), NASA's Solar Terrestrial Relations Observatory (STEREO) and NASA's Solar Dynamics Observatory (SDO). 

Using images from the telescopes on board these spacecrafts, it is possible to determine the speeds, trajectories and morphologies of solar eruptions, to model their behaviour and how it can affect the Earth. Such missions allow scientists to probe deeper into the physics of solar activity, shedding light on the mysteries of our closest star. How cool is that!

This guest post was written by Dr. Jason Byrne, a postdoctoral researcher at the Institute for Astronomy in the University of Hawaii who studied physics at Trinity College Dublin.

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