In this part of the lab, you will be observing the Sun using a solar telescope on the roof. If the weather is cloudy, use the Hydrogen-Alpha photos from the Big Bear Solar Observatory (BBSO) to complete this section. Continue reading below for to learn about which features you may see.
H-alpha features (visible only in H-alpha images) - Certain notable features can only be seen in H-alpha light. These features include:
Granulation - the mottled appearance of the solar disk as seen in Hydrogen Alpha. It will appear as bright patches separated by darker boundaries. Granulation is an illustration of convection in the Sun, the process by which heat flows from the interior to the surface of the Sun. When you are looking at the granules, you are looking at hot blobs of matter that are rising to the surface of the Sun from the even hotter interior, cooling off, then sinking back into the interior again. Since granulation is the process by which heat flows from the center of the Sun to its exterior, it is present even at solar minimum.
Granulation, Image credit: BBSO
Prominences - bright clouds seen at the edge of the Sun against the black of outer space. Often, these appear as bright arches. They are bright because they are hot and made of hydrogen, so according to Kirchoff’s Second Law, they glow in the spectral lines of hydrogen. An amazing thing about prominences is that they are held up against the strong gravitational force of the Sun by magnetic forces.
Prominences, Image credit: BBSO
Filaments - look like long, dark lines on the solar disk . They can only be seen with a hydrogen alpha filter. They represent prominences which are seen in absorption against the light of the Sun, rather than in emission against the dark sky at the solar limb.
Filament, Image credit: BBSO
Solar Flares - (rare) one of the most exciting phenomena to see. Flares are huge explosions on the surface of the Sun. The effects of these explosions can sometimes be detected at Earth, one astronomical unit away. If you see a flare, it will appear as a starlike bright point on the Sun, almost always in the vicinity of a sunspot. It will increase to maximum brightness and fade away in a matter of a few minutes. The tremendous energy associated with solar flares comes from the energy stored in solar magnetic fields.
