Baader Planetarium HERSCHEL PRISM MARK II Instruction Manual page 21

Sunspots
Sunspots consist of a core area (umbra) and a brighter
"halo" (penumbra). Sunspots are cooler (about 4000 °C)
than the undisturbed solar surface (about 5500 °C). At
these points, magnetic fields "break through" the photo-
sphere and interfere with the normal release of energy via
the granules.
All sunspots go through an evolutionary cycle – usually
from a small single spot to a complex group of spots
with magnetic north and south poles. Changes in these
complex groups are the fastest changes observable in
the solar system – they can occur in a matter of minutes, making solar observation in
white light particularly interesting.
Other phenomena to observe
• Light bridges
• Umbral Dots
• Penumbra Filaments
• Schülen-Wilson phenomenon
• Photospheric flares
Flare regions are perceived as brightening of the
solar surface and are usually located around sunspot
groups. These flare regions are hotter than the normal
photosphere. In white light observations with the Safety
Herschel prism, flare regions are mainly observable at
the edge of the Sun (see Fig. right).
Tips for visual observation
If the solar image appears too bright, e.g. when using a very fast refractor or if the
Solar Continuum Filter has been removed (leaving only the ND3 neutral density filter in
the prism housing), either a single polarising filter or an additional neutral density filter
of suitable density must be combined with the ND 3.0 filter. We offer three additional
neutral density filters in densities 0.6, 0.9 and 1.8 – in both 2" and 1¼" filter diameters
– which are also included with the photographic version of the Herschel prism.
All information in this manual refers to the use of the Safety Herschel prism with
refractors with focal ratios between f/6 to f/15.
© Baader Planetarium GmbH | 2024
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