Although the February sweeps officially have been over for several days, Sunday night sure felt like a sweeps extravaganza, with game-changing episodes of two major series. Both pivotal hours, of Sci Fi's Battlestar Galactica and ABC's Brothers & Sisters, dealt with the fate of daughters whose respective departure and arrival is setting off shock waves for their unconventional families (the Galactica crew and the Walker clan).

The episode that undoubtedly will cause the largest stir in TV fandom was Galactica's riveting and ultimately devastating journey into the metaphysical, as Starbuck (a brooding, tormented Katee Sackhoff) finally faced and embraced her destiny. Which meant, in a series of visions and hallucinations guided by the specter of the not-quite-Leobon as if he were the Ghost of Psychodramas Past, that Kara had to confront the soul-crushing memories of her abusive mother, who instilled in the self-destructive Starbuck a belief that suffering was good for the soul. Nobody suffers on Galactica as memorably as Starbuck, and in this final act that took her from "emotional basket case" to a martyr for purposes yet to be determined, this frakked-up hero leaves nothing but suffering in her wake.

I've seen the remaining three episodes of this season, and without giving anything away, I can tell you the shocks just keep coming. Next week's episode picks up two weeks after Starbuck's death - the survivor head count has dropped, notably, from 41,400 to 41,399 - and it's hardly a surprise to learn that no one (Adama, Lee, Sam, even her longtime nemesis Tigh) is taking the loss well. The "celebrity trial" of Baltar ("the most hated man alive") looms and occupies much of the rest of the season, resulting in some of the most potent courtroom drama I've seen on TV in ages, pitting father against son (Adama vs. Lee, yet again) as more revelations in the testimony threaten to tear apart this beleaguered society of military and civilian survivors.

In the prosecutor's opening statement, as the two-part finale begins on March 18, the haunting question "How do we measure loss?" is repeated. Loss, mortality, spirituality, justice and ethical behavior in an epic battle for survival: These themes resonate throughout Battlestar Galactica, transcending the categories of sci-fi and cult TV, which is why the explosive demise of Starbuck didn't play out like just another calculated TV death. (See 24.) Anyone who thinks Starbuck's ultimate destiny (a phrase repeated so often I sometimes felt I'd stumbled into an episode of Heroes) was to disintegrate into a million little pieces doesn't know this show. Anyone who can figure out who and what was waiting for her on the other side, and why, is welcome to explain it to me. And I guarantee nobody will be able to predict the twists in the March 25 season finale, which will make you question everything you thought you knew about nearly everyone and everything. My jaw is still smarting from gaping in astonished disbelief.

The wait between seasons is going to be excruciating.

And now I'll drastically shift gears from space opera to earthbound soap opera, because I couldn't let Sunday's exceptionally entertaining episode of Brothers & Sisters go without comment. This was the episode in which the Walkers all came to grips, and occasionally came unglued, in the wake of learning about the bastard half-sister ( Everwood's effortlessly appealing Emily VanCamp as Holly's daughter Rebecca) who qualifies as a pretty major skeleton in the Walker family closet.

This first season has been all about exposing the secrets and lies of this seemingly successful family, no matter the wrenching cost. The sparks were ferocious indeed and emotionally wrenching when Saul finally caved and told Nora the truth. Ron Rifkin and Sally Field, how great are they? Kudos to this show for giving these splendid veteran actors such juicy scenes to play.

One of the other things I admire most about Brothers & Sisters is how, even when characters do bad things, they're not painted with the melodramatic brush of low villainy. Dynasty this isn't. Thankfully. So it's impossible to hate Sarah (the terrific Rachel Griffiths) even when she does something despicable, like lowering the boom on the unsuspecting Rebecca when she innocently shows up to see her mom's workplace, all to get revenge on Holly, whom Sarah irrationally has cast as a bad guy. True, Holly's reaction to the emotional mess that ensues is all dire threats and recriminations. But she really was the victim in this scenario. Maybe Justin will be the peacemaking mediator. His gesture of goodwill toward Rebecca, in a lovely getting-to-know-you scene that closed out the episode on a grace note, assures us that the family will survive this latest curve ball.

It won't be easy, because what fun would that be? And let there be no doubt. Brothers & Sisters is great fun. Predictable at times, to be sure - you knew it was over for Kevin and Chad when Kevin foolishly called the Drudge-like Internet gossip to try to bully him - and it's neither as ambitious nor ultimately as important as the classics of romantic family drama produced by Marshall Herskovitz and Ed Zwick ( thirtysomething, Once and Again). But it's the perfect escapist hour for Sundays at 10/9c, giving me just the jolt of watercooler buzz I need to start the work week.

And it's a lot less heavy than Battlestar, which on those weeks when I don't get preview screeners is a real chore to squeeze into an already cluttered night of TV. I hope when the next season begins, Battlestar will move back to Fridays, where there's less competition and we get an entire weekend to digest the provocative, profound events as they unfold.