The Sun: Man's Friend & Foe

[Hilltop Dome Facility] The work of astronomers is influenced and sometimes hindered by the Sun in almost everything they do. From the study of the stars and solar system to the study of the Sun itself the area of astronomy is completely inundated with the Sun and its effects. Astronomers cannot see any stars until night, because the Sun's light drowns out that of the stars. When an astronomer wants to look at the Sun during the day special filters must be used over their telescopes as they can't look at the Sun directly or they would go blind. The astronomer Galileo eventually went blind due to his study of sunspots with primitive equipment. He stared at the Sun through a telescope burning his eyes and permanently damaging them.

Latest on SOHO:

The Sun interferes with satellites and other automated spacecraft causing complications in gathering data for astronomers. This can be demonstrated by the recent loss of SOHO (Solar and Heliospheric Observatory). SOHO is a sophisticated spacecraft run by NASA (National Aeronautics and Space Administration) and ESA (European Space Agency). Its purpose is to help scientists understand the interaction between the Sun and the Earth's atmosphere as well as study the internal structure of the Sun, it's outer atmosphere, and solar wind. During a routine maneuver on 24 June, 1998 SOHO lost contact with both the Sun and mission operations. The Sun had emitted a medium-sized solar flare that included a blast of high-energy protons that zapped the cameras on SOHO. The spacecraft was apparently spinning out of control. NASA and ESA have only recently re-established communications.

Astronomers listen to the Sun to learn more about it's inside. The study of wave oscillations in the Sun is called helioseismology. Helioseismology is just a fancy way to say that we can learn about the Sun by "listening" to it. Just like seismologists learn about the interior of the Earth by "listening" to earthquakes astronomers listen to the Sun to learn more about it's insides. For helioseismologists their job is a lot tougher that seismologists as the Sun is so very far away.

The solar "seismic" wave motions that are excited in the Sun's interior have no one cause. Because there is no one source, the sources can be considered a continuum. The ringing Sun is like a bell struck continually with many tiny grains of sand. There are millions of distinct, resonating, sound waves; as may be seen by the doppler shifting of light emitted at the Sun's surface. On the Sun's surface, the waves appear as up and down oscillations. There are three different kinds of waves that astronomers measure and each are equally difficult to study; they are the retrograde wave, the prograde wave, and the standing wave. To better understand the 3 different types of oscillations you should watch our solar oscillations movie (1,012 kb).