HOUSTON -- Jimmy Wynn, whose big league career began one year after Houston became a National League franchise in the 1960s, passed away on Thursday. He was 78.

Wynn, born James Sherman Wynn on March 12, 1942, grew up in Hamilton, Ohio, not far from Crosley Field, home of the Cincinnati Reds. Wynn's hometown team signed him as a 19-year-old in 1962, but the Reds left him unprotected in the Winter Draft later that year, and the expansion Colt .45s pounced at the opportunity.

Wynn debuted with the Colt .45s in the middle of the 1963 season, and soon, his star power in the Space City skyrocketed.

Before Cesar Cedeno, Richard Hidalgo and Carlos Beltrán, there was Wynn, Houston's first slugging center fielder. This was despite one major potential pitfall that could have stood in his way -- size. He was small. The Astrodome was not. Neither ended up being much of an issue.

Wynn, listed at (a somewhat generous) 5-foot-9, hit 37 home runs in 1967 and at least 20 in seven other seasons, all the while playing half his games in the cavernous, pitcher-friendly Astrodome, home of thousands of fly balls that met their demise at the warning track. Despite the Astrodome's deep dimensions of 340 feet down the foul lines, 375 to the power alleys and 406 to center, Wynn finished his career with 97 home runs in 678 games at the Dome.

"That ballpark was built for defense and speed," Wynn said during an interview with MLB.com during the Civil Rights Game festivities at Minute Maid Park in 2014. "If you hit one there, it wasn't a cheapie."

Wynn had several stunning single-game moments, but none more famous than the home run he hit on April 12, 1970, when he became the first player to hit a regular-season home run into the upper deck of the Astrodome. Nine days earlier, Doug Rader hit a ball in almost the exact same spot to become the first Astros player to reach those gold-colored seats, but that was during an exhibition game against the Yankees. Wynn's was the first when the games counted.

In those days, home runs weren't measured. But it's fair to say the ball traveled somewhere in the neighborhood of 430 feet.

To commemorate the feat, the Astros reupholstered the seat the ball hit with the image of a cannon, and when the Dome was renovated in the 1980s, the Astros gave Wynn the seat.

The combination of his short stature and herculean strength earned him the nickname "Toy Cannon," given to him by a local newspaper reporter. At first, Wynn didn't like the nickname, but after hearing fans chanting Toy Cannon, he embraced it as part of his identity as a ballplayer.

"At times, I forgot my real name," Wynn said in '14. "If I hit a ball hard -- or out of the park -- I'd go back to the bench and look out to the mound to see the pitcher saying, 'How in the world can that little man hit the ball so far and so hard?' And then I got the reputation of being a power hitter and a home run hitter, so they pitched me a lot different.

"I lifted weights without people knowing about it. I kept my upper body, my hands and my wrists strong. That's where I got my power."

Wynn hit 223 homers as an Astro, a club record until Jeff Bagwell surpassed him in 1999. Fittingly, Bagwell set the record after hitting three home runs in a single game at Wrigley Field. Bagwell and Wynn, at that time, were among only four Astros players to hit three homers in one game.

Wynn's career spanned 15 years. Following his Astros tenure, he played two seasons with the Dodgers, followed by tours with the Braves (1976), Yankees (1977) and Brewers (1977). Over 1,920 Major League games, Wynn slashed .250/.366/.436 with an .802 OPS.

The Astros retired Wynn's uniform No. 24 in 2005, at which time Drayton McLane, then the owner of the club, asked him to serve as an ambassador for the team. Wynn had been in that role ever since, as an active participant with the team's community outreach program.

"The Astros have been my life," Wynn said. "They gave me an opportunity to bring my skills out. It gave me a chance to realize my dream."

One of his final public appearances in an Astros setting occurred last season, when he was one of 16 team legends to be inducted as the inaugural class of the Astros Hall of Fame. The honor arrived 14 years after his uniform number was officially hung on the rafters among the other Astros immortals.

When Wynn would look at his jersey high atop Minute Maid Park, he’d note the warm feeling that overcomes him every time he glances in that direction.

"You know, it makes me feel I've done something in baseball and here in Houston," he once said. "As I get older, it means more to me. When I sign autographs at games, people point to that number. It's just a special feeling to be appreciated."