The blink comparator is the optical instrument that detected Pluto's discovery in 1930, comparing photographic plates taken on different nights to spot moving celestial objects. As Pluto marks its 95th anniversary since discovery, the same technique remains foundational to modern planetary astronomy, with scientists now using similar methods to search for undiscovered planets at the solar system's edge.
·The blink comparator works by rapidly switching between two photographic plates to reveal objects that have shifted position between observation dates
·Pluto won't complete its first full orbit since discovery until 2178, taking 248 Earth years to circle the Sun
·Modern astronomers employ digital versions of the blink comparator principle to scan for hidden planets beyond Neptune's orbit
·The February 18, 1930 discovery of Pluto at Lowell Observatory remains one of astronomy's landmark achievements using mechanical instrumentation
·Recent discoveries like comet 3I/ATLAS demonstrate the enduring effectiveness of comparative imaging techniques for detecting faint solar system objects
drawn from National Air and Space Museum, Space Daily, BBC Sky at Night Magazine, The Planetary Society · updated 30d ago