Here is the latest article from the Astronomy site at BellaOnline.com.
Pluto - Names and Places
New Horizons was nearing Pluto in 2015 and the mission team would need names for the surface features they discovered. So they appealed to the public. The names would be informal ones, but they hoped the International Astronomical Union (IAU) would make them official.
*Pluto's discoverer and the blink comparator*
Clyde Tombaugh was hired to look for the Planet X that Perceval Lowell thought was out there somewhere beyond Neptune. This picture shows Tombaugh, not with his telescope, but with the "blink comparator". https://planetary.s3.amazonaws.com/assets/images/9-small-bodies/2013/20130129_tombaugh.jpg
He used the telescope to photograph the night sky, getting images of the same areas of sky at different times. Why? Well, what do planets do that stars don't? They move. The blink comparator "blinked" two images back and forth quickly so that an object that wasn't in the same place in both images could be distinguished from the fixed stars.
Not as easy as it sounds, of course. Have a look here – you can try to find Pluto yourself. And with the advantage of knowing that it is there to be seen. Tombaugh had quite a job carefully searching pairs of plates just in the hope of finding something. https://imgflip.com/gif/lrk1e
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I wish you clear skies.
Mona Evans, Astronomy Editor