When Glenn Schneider met Joe Rao, it was a moment in the sun.

It was 1973, and the teens had both come from The Bronx to the Hayden Planetarium for a presentation. By chance, they ended up next to each other. An announcement was made that Charles Smiley — one of the world’s foremost experts on eclipses, who had seen 13 of them — was also there.

“Glenn leans over to me and says, ‘I’m going to leave Dr. Smiley in the dust,’ ” Rao recalled. “ ‘I’m gonna see every total solar eclipse from now till I die.’ ”

The two became fast friends and joined the same astronomy club. The Post first wrote about them in 1977, when they were preparing to view the Perseid meteor shower.

Rao become a meteorologist in Westchester; Schneider, an astronomer in Arizona — and one of three people on Earth who have witnessed 33 total solar eclipses.

“The only one that he missed, which he’s still pissed off [about], was in 1985 when he wasn’t able to find a [boat to take him out] for an eclipse that passed over Antarctica,” Rao, who has seen 11 eclipses, said. “He was in fits for weeks.”

Over the years, the two have reunited to view four total eclipses. But for the August event, Schneider will be in Madras, Ore., and Joe will take to the skies: For the second time, he’s convinced Alaska Airlines to run a special flight 1,000 miles off the Oregon coast just so passengers can view the eclipse.

“We’re gonna be the first to see the Great American Eclipse,” Rao gushed of the flight.