isompisäteiset

Isompisäteiset is a Finnish term that translates to "larger-rayed" and is primarily used in the context of astronomical observations, specifically referring to celestial objects that exhibit wider diffraction spikes when viewed through a telescope. These diffraction spikes are not inherent physical properties of the stars themselves, but rather artifacts created by the interaction of light with the telescope's optical components, such as the secondary mirror support vanes or aperture irregularities.

The perceived size and prominence of these "larger rays" can depend on several factors. The design and construction of the telescope play a significant role; for instance, telescopes with thicker or more numerous support vanes for the secondary mirror will generally produce more pronounced diffraction spikes. The atmospheric conditions, known as seeing, also influence the clarity of the image and can make these spikes appear sharper or more diffuse. Furthermore, the brightness of the celestial object itself can affect how visible the diffraction spikes are. Brighter stars tend to produce more noticeable rays.

Astronomers sometimes refer to objects as "isompisäteiset" when the diffraction spikes are a notable characteristic that might, for example, aid in identifying a specific telescope used for an observation or when they are a factor in image analysis. While not a formal scientific classification, the term is understood within observational astronomy circles in Finland to describe this visual phenomenon.