He was an 18-year-old pitcher in 1965, just beginning to pursue his Major League dream. When the Houston Astros returned from Spring Training, the bus rolled in from the airport to give the players a look at their amazing new home.
Until then, baseball had never been played indoors. Even as the Astros watched the mammoth structure take shape over the previous three summers, they had trouble grasping it.
In the beginning, that notion seemed as crazy as landing a man on the moon. Baseball had always been played in cozy little ballparks made of steel and brick and wood. Creature comforts weren't given a second thought.
To envision a structure with a massive gleaming white roof and exploding scoreboard and theater seats was too much for some. And then that evening, the bus door opened and the players saw it for the first time.
"It was absolutely breathtaking," Dierker said. "They had this huge scoreboard lit up. The colors were so vivid, eye-popping."
The Astrodome began as one man's improbable dream, a crazy dream really, this notion that baseball could be played indoors. That one man, Judge Roy Hofheinz, believed we were limited only by the horizons of our dreams.
"Judge Hofheinz was so dynamic," said Bob Bruce who threw the first regular-season pitch in the Astrodome. "He could sell anybody anything. He believed in it, and if you knew him, you believed he could make it happen."
The Astrodome would come to represent the pioneering, fearless, risk-taking American spirit at its best. In 1965, we were going to send a man to the moon, and so when NASA located its headquarters in Houston, the Colt .45s were transformed into a name perfect for the space age.
The Astrodome was a seminal moment in the emergence of a world-class city, and to the end, THAT'S what they celebrated Saturday night at Minute Maid Park on the 50th anniversary of the Astrodome's first regular-season game.
They brought six members of the 1965 Astros back for the day, and just as they'd done before that first game, a collection of astronauts threw out ceremonial first pitches to them.
The Astros wore uniforms like those they'd worn in 1965, and it was all a way to honor a man and an idea and a city.
"If it wasn't for Judge Hofheinz getting this built, baseball wouldn't have survived in Houston," said Jimmy Wynn, a pint-sized slugger and one of the franchise's first stars. "The heat and humidity was just too much."
Hofheinz dreamed big and compelled others to dream big, too. The Astrodome was an engineering miracle, but that's the least of it. It required vision and courage and risk. It required money, too, lots of it, $35 million or so, a monumental amount for that time and place.
Generations of Houstonians came to see the Astrodome as something more than a place for their baseball team to call home. Rather, it was symbolic of their collective will.
"It had an incredible impact on this city," said Bob Aspromonte, a third baseman on the 1965 Astros and a resident of Houston ever since. "When I arrived here in 1962, there might have been 500,000 people in the city. We had two million people visiting the Dome without games being played."
The Astrodome helped change a city in ways that those older players still think about. They are proud of their part in it, that no one could ever look at Houston the same way again.
"The Colt .45s never had a lot of attention," Bruce said. "All of a sudden, we had dignitaries from all over the world. We had President [Lyndon] Johnson, movie stars."
They had fans, too. The Colt .45s drew 725,000 in 1964. The Astros drew 2.1 million in 1965.
"It was a unique time in Houston because of the astronauts," Bruce said. "They were rock stars. You could feel the excitement, and we became part of it.
The Astrodome wasn't just the first indoor stadium. For its entire existence, it was also the best, with its plush seating, airy concourses, restaurants and nearly perfect sight lines. It took the idea of going to a baseball game and transformed it into an experience of new sights and senses.
On April 18, 1965, the Phillies beat the Astros 2-0 in front of 42,652 in that first game. It was their home for 35 seasons. Along the way, the Astrodome hosted other big events.
In 1968, UCLA and Houston played one of the great college basketball games ever played. In 1973, Billy Jean King defeated Bobby Riggs in a tennis match that became a referendum on women's equality. Elvis Presley played the Astrodome six times, and the Stones and Bob Dylan and others lit the place up, too.
In the years after 1965, Houston would become the home of a world-class medical center and become a powerhouse in the energy industry. There would be an arts district comparable to almost any.
Everything Houston would become flowed from NASA and the world's first indoor stadium. Now, at a time when local officials are struggling with how to utilize the Astrodome's structure in the years ahead, Saturday was a reminder of its significance.
"It was an incredible success," Aspromonte said. "I feel strongly about this. It's an important part of our history."
Richard Justice is a columnist for MLB.com. Read his blog, Justice4U. This story was not subject to the approval of Major League Baseball or its clubs.