If you want to wish on the first star you see tonight, there’s a good chance it’ll be Arcturus.
As you make your wish, you can also think about how Arcturus became famous in 1933 when its starlight opened the Chicago World’s Fair. On May 27, at 9:15 p.m. central time, several observatories aimed telescopes at Arcturus and focused its light onto photocells. The current that was generated resulted in the flipping of a master switch for the fair’s lights.
According to an article published the next day in the New York Times, “the grounds, pavilions and waterways of the fair were drenched with light. Thousands of awed beholders broke into cheers.”
Why was Arcturus chosen for this honor? It was thought to be 40 light years away, meaning that the light reaching Earth in 1933 would have left Arcturus forty years earlier, in 1893—when Chicago previously hosted a World’s Fair.
Unfortunately, they picked the wrong star. We now know that Arcturus is actually about 37 light years away.
So if you spot Arcturus tonight, you see it as it looked 37 years ago, in 1973, when the light left it. Looking deep into space is like having a time machine into the past.
To learn to identify Arcturus and other stars and constellations, come to Morehead’s skywatching session on Saturday, June 19. Or register for Starry Summer Nights; this class for adults takes place Tuesday evening, June 22, under the planetarium dome.
Arcturus is probably pretty much the same now as in 1973, but it’s still fun to think about.