LINCOLN, Neb. — So long, Big 12. Nebraska’s membership in the Big Ten Conference is official.

The Big Ten’s board of presidents and chancellors unanimously welcomed Nebraska to the club on Friday, just a few hours after the school formally disclosed its interest. The move takes effect July 1, 2011.

Nebraska chancellor Harvey Perlman said the Big Ten offers stability “that the Big 12 simply cannot offer.”

Nebraska is the Big Ten’s first addition since 1990, when Penn State joined, and it comes just six months after the league announced that it was looking at expansion.

Big Ten commissioner Jim Delany said he presumed there would be a Big Ten championship football game beginning in 2011. He also said the conference would “pause” from further expansion over the next 12 to 18 months. He declined to comment on whether Notre Dame or any other school was on the league’s radar.

Nebraska’s departure is a potentially crippling blow to the Big 12 and the biggest move yet in an offseason overhaul that will leave college sports looking much different by this time next year.

“We’ve had a couple disappointing days with the departure of two valued members,” Big 12 commissioner Dan Beebe said during a teleconference. Beebe vowed to work to keep the 10 remaining members together but acknowledged that other Big 12 schools are mulling their options.

Perlman said he believed Nebraska is much more “aligned” with the Big Ten than the Big 12 when it comes to academics, culture and athletics.

The university issued a statement that said for more than 20 years, Nebraska has compared itself to a list of 10 peer institutions established by the regents. Five of the 10 are Big Ten members; four are former Big Eight schools that joined Nebraska in the Big 12 in 1996.

“The University of Nebraska would have new opportunities with membership in the Big Ten — and I believe the Big Ten would be a stronger conference as well,” university president J.B. Milliken said.

Nebraska’s move comes at the end of a crazy week in college athletics.

On Thursday, fellow Big 12 member Colorado announced it was leaving for the Pac-10. Texas and other schools in the Big 12 South — Perlman told the regents that the Pac-10 had been in touch with many schools in that division — could be the next to leave. Texas regents scheduled a meeting for Tuesday to discuss the Longhorns’ future in the Big 12.

“One school leaving a conference does not destroy a conference,” Perlman said. “Nebraska did not start this discussion. After the Big Ten announced it planned to consider expansion, we saw reports that Missouri would want to go to the Big Ten, including a statement by their governor, a member of board of curators and chancellor — comments that weren’t clearly supportive of the Big 12.”

Athletic director Tom Osborne, the longtime football coach, agreed.

“As we read the tea leaves and listened to the conversations, some of the schools that were urging us to stay, we found some of them had talked to not only one other conference or two but even three, and those were the same ones urging us to stay,” he said.

To generations of Nebraska fans, going to the Big Ten at one time would have been unthinkable. The school’s athletic tradition is built on more than a century of football games against the likes of Missouri and Kansas, dating to the days the team was known as the Bugeaters.

The Huskers, in fact, have been conference partners with Iowa State, Missouri, Kansas, Oklahoma and Kansas State since 1928; with Colorado since 1948 and with Oklahoma State since 1960.

Now the Huskers are on the verge of taking their five national titles in football, three Heisman trophies and enthusiastic fans east. They will look to start building new traditions, like a border rivalry with the Iowa Hawkeyes and regular trips to Ohio State, Michigan and Penn State.

Watching a football camp at Beaver Stadium, Penn State coach Joe Paterno declined comment Friday. Paterno in the past has advocated for enlarging the Big Ten from 11 schools to 14.

“It’s just the tip of the iceberg right now,” Penn State receivers coach Mike McQueary said of Nebraska. “Unbelievable tradition, the things they’ve done in that program; academically as well.”

At Iowa State, a Big 12 school rarely mentioned in realignment discussions, officials sent an open letter to boosters expressing disappointment in the moves by Colorado and Nebraska.

“But as all of the discussions about conference realignment illustrate, the future of college athletics appears to be less about academics and competitive success and more about money, as measured by television viewership and the associated revenues,” the letter said.

Fatter paychecks will be coming to Nebraska, eventually. Nebraska received about $10 million from the Big 12 in 2009, half the $20 million received by Big Ten members (thanks largely to bigger television contracts and the in-house Big Ten Network).

The Big Ten told Perlman that no current member would receive a reduced share of revenue from the conference because of the addition of a new member. Perlman said Nebraska has been assured it would not receive less than it did in the Big 12, however, if it joins the Big Ten.

“This is not a financial windfall,” Osborne said.

Delany has said he wanted to add only members that would be considered “home runs.” The Huskers’ football team struggled in the early and mid 2000s but have returned to national prominence the past two seasons under coach Bo Pelini, an Ohio State alumnus.

As for the Big 12, it never was a comfortable fit for the Huskers.

When the league formed, Nebraska football was at its pinnacle, having won three national titles between 1994-97 and winning 60 of 63 games before Osborne retired as coach.

That success didn’t translate to juice when it came to influencing league policies.

Nebraska and the old Big Eight members, all of whom went to the Big 12, believed they were helping out Texas, Texas A&M, Texas Tech and Baylor when the old Southwest Conference collapsed.

The perception in Nebraska was that the Big 12’s balance of power was held by the South Division, particularly the University of Texas.

Nebraska from day one was against a championship game in football, for fear it could trip up a team bidding for a national title. But even issues ranging from academic admission standards to location of the league office (Dallas) chafed Nebraska.

When the league last week picked Cowboys Stadium to host the next three conference championship football games — after hosting the 2009 and 2010 games — Osborne complained that continual treks south are unfair to fans of the North representative.

And no one in Nebraska has forgotten the controversial outcome of last year’s conference title game. It looked like the Huskers had beaten the Longhorns 12-10 when the clock ran out, but one second was put back on, allowing Texas to kick the winning field goal. Pelini yelled outside the locker room that Texas was given the extra second so it could go to the BCS championship game.

“This is not about any type of vindictiveness,” Osborne said. “You don’t make a decision of this size based on where you’re going to play Big 12 championship games.”