Studying the Solar System and the Sun

Humanity has always been fascinated by the sun. As technology developed, people examined the sun more closely.

The first in a series of orbiting solar observatories was launched in 1962 and functioned for 18 months.

In late 1995, an Atlas rocket launched SOHO, the Solar Heliospheric Observatory toward a solar orbit 1.5 million kilometers from earth where gravity from both the sun and the earth act equally on the space craft.

SOHO is providing scientists with a comprehensive study of the sun. Its 12 experiments developed by scientists from Europe and the United States are investigating the sun from its core outwards to the solar wind.

On earth, we are screened from most of the dangerous parts of this radiation by our atmosphere and the earth’s magnetic field. But during extreme solar activity, charged particles can spiral in along the earth’s magnetic field lines.

Solar flares are the most violent manifestations of the sun at the peak of its solar cycle. SOHO has shown that powerful starquakes ripple around the sun in the wake of these mighty solar flares.

Scientists are starting to get a better understanding of how the sun is structured. SOHO also monitors the solar wind providing an early warning when a coronal mass ejection is headed towards the earth. Heavy bombardment of these particles will have a range of effects.

Auroras occur in the northern and southern skies at times of solar storms—the charged particles causing ionization of atoms in the upper atmosphere. Satellites can be damage and power grids can overload or malfunction.

Scientists say it’s impossible to overstate the importance of SOHO to the worldwide solar science community. After the last 13 years, SOHO has revolutionized ideas about the solar interior and atmosphere and the acceleration on the solar wind.

We can now see images of the sun’s turbulent outer region known as the convection zone as well as sun spots which actually lied beneath the solar surface.

The SOHO probe was only intended to operate for two years. After 13 years, it still functions well. The team is keen to keep the solar observatory operating at least until the next solar maximum because SOHO has picked up clues that suggests the next active period could be one of extreme violence.

To get a better view of the sun, NASA has launched two new probes designed to work attainable. Called Stereo A and Stereo B, one is flying just inside and slightly ahead of the earth orbit while its twin is flying outside earth orbit of the sun and slightly behind it.

The three dimensional images of the sun can help scientists to predict when and how hard dangerous solar storms will hit the earth.

The SOHO Observatory is already providing some information but the two Stereo spacecraft will be able to triangulate with SOHO and give a much better view of these bursts as they butt off the sun surface.

The solar atmosphere gives no clues to help us judge distance. Everything up here is flat in the two dimensional plane in the sky. Having a stereo perspective makes observations much easier.

Knowing where the front of the coronal mass ejection cloud is will improve estimates of the arrival time from within a day or so to just a few hours.

These plumes of charged gas are huge and there will be times when they will engulf one the stereo craft enabling it to measure the magnetic field inside the storm.

Earth directed solar explosions tend to happen every 27 days—the time it takes for some spots to rotate once around the sun. There is also an occasional 155 day cycle of solar flares.

We are still not certain why this is so.