Topic 3.2 - Observing the Night Sky 0.0 / 5 ? AstronomyObserving the Night SkyGCSEEdexcel Created by: goldstar3Created on: 02-06-18 12:24 A) RA and Declination Celestial co-ordinates RA is measured eastwards form Spring Equinox 1hr of RA = 15 degrees Declination is the angular distance N/S of the celestial equator Celestial equator crosses ecliptic at spring equinox and autumnal equinox 1 of 3 B) Polaris Declination +90 degrees It appears fixed because it is in almost the same direction as the Earth's axis 2 of 3 J) Naked Eye Observing Techniques Dark adapted eye: It can take 7 mins for eyes to become used to darkness & 30mins to become totally adjusted Red torches do not affect the dark adapted eye Best when Moon is not well lit & to look for fain objects Relaxed Eye: Easier for eye to refocus on objects Possible to view for extended periods Eye is not stressed If object isn't bright enough then cone cells aren't stimulated Look slighty to side of the object, stimulating rods allowing object to be seen 3 of 3
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