Hours with a Three-inch Telescope |
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70 Ophiuchi angles aperture appear Aquarii Aristillus Arzachel astronomical Auriga axis beautiful binary star Böotis bright Canes Venatici centre companion components conspicuous constellation contrasted colours Cor Caroli crater curious Cygni dark limb days old described disc double star Draconis draw earth east easy pair equatorial equatorially mounted Eratosthenes examination eye-piece formation full moon Herculis illuminated imaginary line inch inferior conjunction instrument interesting interior Jupiter larger star light looking lunar marked Mars Messier miles in diameter Moon's Age mountain mounted naked eye nebula night object object-glass observer's occultation Ophiuchi orbit Orionis planet pole power of 160 present pretty pair R. A. Proctor reappear represented in fig ring ring-plain round satellite Saturn seen selenography Serpentis shadow shown in fig sketch small stars spot streaks strike student sun's surface terminator terrestrial three-inch telescope tint Tycho unequal pair Uranus Venus visible young observer