Jim Thome's age as of Aug. 6 is 40 years, 344 days; he will be the oldest to reach 600 homers by more than two years. He has 8,141 at-bats.

BABE RUTH

 

Hit No. 600: for Yankees, Aug. 21, 1931, off Browns' George Blaeholder in St. Louis. Age: 36 years, 196 days. At-bats: 6,921 (fewest at-bats to 600). AB/HR: 11.54.

He was in a tight race with teammate Lou Gehrig for the league lead, so Ruth's 600th was just as notable at the time for being his 35th of the season -- and Gehrig followed immediately with a home run of his own, No. 35. (They would finish the season tied with 46.) Ruth wasn't around to celebrate his achievement for long, though -- he was ejected in the eighth inning by umpire Roy Van Graflan for arguing about whether a St. Louis home run had cleared the fence.

WILLIE MAYS

Hit No. 600: for Giants, Sept. 22, 1969, off Padres' Mike Corkins in San Diego. Age: 38 years, 139 days. At-bats: 9,514. AB/HR: 15.8.

He wasn't in the Giants lineup for a game with the expansion Padres, but he was called upon to pinch hit for rookie George Foster -- who would hit 348 big-league homers of his own -- in the seventh inning of a tied game. The entire Giants team greeted Mays as he reached home plate, and the tiny San Diego crowd bestowed a five-minute standing ovation, demanding two curtain calls. The Adirondack Bat Company presented Mays with a $12,500 sports car and one share of stock in the company for each foot of his 390-foot blast.

HANK AARON

Hit No. 600: for Braves, April 27, 1971, off Giants' Gaylord Perry in Atlanta. Age: 37 years, 81 days. At-bats: 10,014 (most at-bats to 600). AB/HR: 16.69.

After hitting No. 599 the day before, he tried to get to 600 on his first at-bat but doubled off the wall -- which tied him for eighth on the all-time doubles list with Harry Heilman. His next time up, Aaron reached 600 with a towering fly ball to left off a Gaylord Perry pitch. But Mays, of all people, spoiled the party by collecting four hits, including a 10th-inning RBI single to win the game.

BARRY BONDS

Hit No. 600: for Giants, Sept. 9, 2002, off Pirates' Kip Wells in San Francisco. Age: 38 years, 16 days. At-bats: 8,211. AB/HR: 13.69.

No. 500 had come just one season earlier, a 710-at-bat span that was the fastest climb to 600 by far. The countdown ended when he crushed a Kip Wells pitch against his former team, the Pirates, setting off fireworks in Pac Bell Park and a fistfight for the ball in the left field bleachers. Bonds was congratulated by his father, Bobby, who was dying from kidney cancer.

SAMMY SOSA

 

Hit No. 600: for Rangers, June 20, 2007, off Cubs' Jason Marquis in Arlington, Texas. Age: 38 years, 220 days (oldest to hit 600). At-bats: 8,637. AB/HR: 14.40.

After sitting out the 2006 season, in part because of the controversy over his suspected steroid use, he returned in 2007 -- mostly, many believed, just to hit the last 12 home runs he needed to reach 600. He got them with the Rangers, the team that originally signed him. He bashed No. 600, then did his trademark hip-hop out of the box, off his former team, the Chicago Cubs, and a pitcher, Jason Marquis, wearing his old No. 21.

KEN GRIFFEY JR.

Hit No. 600: for Reds, June 9, 2008, off Marlins' Mark Hendrickson in Miami. Age: 38 years, 200 days. At-bats: 9,042. AB/HR:15.07

His 14-year-old son, Trey, was acting as Reds batboy when Griffey connected in a huge venue that looked nearly empty -- Dolphin Stadium in Miami, where only an announced 16,600 were in attendance for the event. Still, the fans insisted on a curtain call, and Griffey, who needed 69 games to collect the final seven home runs to reach the round number, finally obliged. Two months later, he was traded to the White Sox.

ALEX RODRIGUEZ

Hit No. 600: for Yankees, Aug. 4, 2010, off Blue Jays' Shaun Marcum in New York. Age: 35 years, 8 days (youngest to 600). At-bats: 8,688. AB/HR: 14.48.

The youngest player ever to reach 600, Rodriguez seemed more relieved than honored when he finally reached the mark, since nobody had ever experienced such a gap between 599 and 600. It took the Yankees star 46 at-bats to reach the milestone, 21 more than Mays (the previous slowest) needed, and 43 more than Aaron, the fastest. Sign of the times? Once the ball landed in Yankee Stadium's monument park, the team put a congratulatory message on the scoreboard -- immediately followed by an announcement that commemorative programs and T-shirts were on sale.