Get ready for some great out-of-this-world television

Fans of outer-space adventures are in for extra helpings of sci-fi goodness as three of the genre's most popular TV shows return with new episodes tonight.

The critically celebrated "Battlestar Galactica," "Stargate SG-1" and its spin-off "Stargate Atlantis" wrap up cliffhangers and resume their current seasons on the Sci Fi Channel.

"Stargate SG-1" and "Atlantis" kick off the evening at 8 p.m. and 9 p.m. respectively with two hours of fast-paced fun, but "Galactica" at 10 p.m. is really the show to watch — especially if you enjoy Fox's "24" or Showtime's "Sleeper Cell."

"Galactica" takes these shows' serious, contemporary themes — the global war on terrorism, for example — and "re-imagines" them in an alternate reality, giving "Galactica's" creators' lots of latitude to explore them in new ways.

Tensions are running high as "Galactica's" latest episode opens. Cmdr. Adama (Edward James Olmos) has scrambled his fighter ships to attack Pegasus, one of Galactica's sister vessels that also survived annihilation at the hands of the robotic Cylons.

Pegasus' commander, Adm. Cain (Michelle Forbes) has sentenced two of Adama's crew to death after they accidentally killed one of her officers when he tried to rape Lt. Sharon "Boomer" Valerii (Grace Park). Boomer was jailed after being exposed as a Cylon sleeper agent.

On Cain's ship, Cylon agents, including a new incarnation of Tricia Helfer's Number 6, are tortured and raped by officers and crew.

When Lt. Kara "Starbuck" Thrace (Katee Sackoff) returns from a spy mission with information that could hurt the Cylons, Cain and Adama must decide whether they can trust each other long enough to defeat their enemy.

This back story is the catalyst for unexpected plot twists and character developments that should continue to keep "Galactica" fans riveted as the rest of the season unfolds.

The frequent use of scenes involving a couple of characters makes for some powerful performances and healthy on-screen time for some of the show's young stars.

Two-time Oscar nominee Mary McDonnell nails her role as President Laura Roslin, convincingly making life-and-death decisions even as she battles terminal cancer. Forbes, who is a veteran of shows like "Star Trek: The Next Generation" and "24," is well cast as Cain and even better in the cliffhanger's continuation as she effectively portrays her character's tormented determination to survive.

Of course, "Galactica" also includes high-quality special effects for hardcore sci-fi fans and, for its mainly male audience, some sexy shots of former model Helfer with the polished James Callis, who plays the twisted, yet endearing, Dr. Gaius Baltar.

While "Galactica" brings serious drama to the sci-fi genre, "The Gates" are perfect for winding down the work week with their mix of humor and action.

"Stargate SG-1" picks up the story of the Ori, the latest group of galactic thugs who want humans to worship them as gods. It features several notable stars, including Louis Gossett Jr. as misguided Jaffa leader Gerak and William B. Davis, the "X-Files" cigarette-smoking man, as one of the Ori's henchmen. Don S. Davis also makes a cameo as Gen. Hammond, the SG team's former commander.

Former "Farscape" star Ben Browder (Lt. Col. Cameron Mitchell) and "SG-1" veteran Michael Shanks (Dr. Daniel Jackson) are developing some fun on-screen rapport, but side stories involving principals Amanda Tapping (Lt. Col. Samantha Carter) and Christopher Judge (Teal'c) aren't as memorable. And some of the episode's scenes seem unnecessarily corny and contrived.

While "SG-1" continues to reinvent itself with new heroes and enemies, the cast of "Stargate Atlantis" is settling into its extra-galactic surroundings quite well. In fact, the show and its stars seem to be having lots of fun. Case in point: Dr. McKay's (David Hewlett) hysterical reaction to the Wraith's superstrength enzyme, is a side splitter.