SALT LAKE CITY  — The University of Utah accepted an invitation to become the 12th member of the newly expanded Pac-10 Conference on Thursday.

“Today is an absolutely great day to be a Ute,” athletic director Chris Hill said before he was interrupted by applause during a news conference.

The room was packed with Utah dignitaries, boosters and dozens of red and white balloon bouquets. University president Michael Young made it official by signing the agreement, bringing another extended round of applause.

The announcement was held at Rice-Eccles Stadium, where the Utes enjoyed two undefeated seasons in the past six years. The Utes received invitations to the Bowl Championship Series in 2004 and 2008, but both were at-large bids. Utah is the first team from a non-BCS conference to reach the premier bowls twice.

“I don’t really know if you can compare the two, but there’s a lot of the same feelings and a lot of the same excitement going on right now,” football coach Kyle Whittingham said.

By joining the Pac-10, the Utes’ BCS-busting days are ending. After playing one final season in the Mountain West, Utah will join the Pac-10 — or whatever the expanded league’s name will become — in 2011. There is a guaranteed BCS spot for the Pac-10 winner, but that will mean getting through a schedule of one of college football’s most prominent conferences.

“First and foremost, the reason this has happened is because the athletes that we’ve had at the University of Utah have worked so hard and done so much to put this program on the map,” Whittingham said. “That really is where the lion’s share of the credit goes to.”

Young noted that the Utes are 7-3 against Pac-10 football teams in the last 10 meetings, including wins over Oregon in 2004 and Oregon State four years later during the Utes’ two unbeaten runs to the BCS.

The leap takes the Utes from the Mountain West, where national television appearances are rare, to the major markets of the Pac-10. Hill pointed out that representatives from the Rose Bowl were on hand for Thursday’s announcement.

The Utes were the only unbeaten team in 2008, and they didn’t get a chance to play in the BCS title game. A rout of Alabama in the Sugar Bowl bolstered Utah’s claims of being worthy. The Utes ended up finishing No. 2 in the final AP poll — the school’s highest finish.

The Utes also have strong programs in men’s and women’s basketball, women’s gymnastics that could immediately compete in the Pac-10. In sports like baseball and tennis, the Utes will be making a tremendous leap in competition.