Frank Thomas hit his 500th home run Thursday, routinely putting his head down as he rounded the bases while joining one of baseball's most elite clubs.

The Toronto slugger became the 21st major leaguer to reach the career mark, a milestone that has usually meant an eventual spot in the Hall of Fame.

Thomas hit a three-run shot in the first inning, connecting against Minnesota's Carlos Silva and sending a 1-2 pitch an estimated 396 feet into the left-field stands.

Todd Eisenlohr, sitting in the fifth row and wearing a jersey of Twins player Jason Bartlett jersey, caught the ball in his glove.

"I lost it in the roof as it was coming down,'' Eisenlohr said. He said he traded the souvenir ball for an autographed ball, bat and jersey.

The Metrodome crowd gave Thomas a standing ovation. The two-time AL MVP took his home run trot and then pointed toward the suites down the right-field line when he crossed the plate as Toronto players spilled out of the dugout to congratulate him.

That Thomas did it in the Metrodome was fitting. He hit his first career home run at the ballpark against Gary Wayne while with the Chicago White Sox on Aug. 28, 1990. Thomas has 16 homers overall at the stadium.

The 39-year-old Thomas is in his first season with the Blue Jays. He played last year in Oakland.

Next on Thomas' ascent on the career home run list are Eddie Murray (504), Mel Ott (511) and Ernie Banks and Eddie Mathews (512 each). Also within reach of 500 this year are Alex Rodriguez, Jim Thome and Manny Ramirez.

Thomas entered Thursday with four home runs in his previous 10 games. He has 13 this season. This was his second lifetime homer off Silva.

The Big Hurt has hit 50 career homers against the Twins, his most against any team and the most by an active player against Minnesota. Rocky Colavito hit 52 against the Twins and Mickey Mantle and Reggie Jackson each hit 51.

The seventh overall pick by the White Sox in 1989, Thomas spent 16 years in Chicago and established many franchise bests, including 448 home runs, 1,465 RBIs and 3,949 total bases. His .427 on-base percentage and .568 slugging percentage are also franchise bests.

But an injured ankle limited Thomas to 108 games in his final two seasons and led to a falling-out with the team.

After joining Oakland as a free agent, Thomas hit 39 home runs and drove in 114 runs last year in helping the A's reach the AL championship series. He signed with the Blue Jays as a free agent on Nov. 17, 2006.