MarsCon kicks off science-fiction convention season. Founded in 1999 by a handful of sci-fi fans, it is somewhat smaller than the annual CONvergence, but its strength is in its breadth. It promises something for just about every kind of geek — costumers, sci-fi lit fans, TV and movie geeks, astronomy and science enthusiasts, prop masters, gamers and animé aficionados. The weekend includes Q&A sessions, film screenings, panel discussions, gaming, an art show, literary readings, live music and themed party rooms, with guests of honor including actress Spice Williams-Crosby (best known as a Klingon in “Star Trek V” and an assassin on “Buffy the Vampire Slayer”) and the semilegendary Antoinette Bower, a fixture on sci-fi TV shows from the ’60s through the ’80s. (Fri.-Sun. $30-$75. Hilton, 3800 American Blvd. E., Bloomington. Jahna Peloquin



Minneapolis Polar Plunge

Among the craziest things Minnesotans do: diving into freezing water for sport. The annual Polar Plunge pops up at lakes across the state, with thousands jumping in to raise money for Special Olympics Minnesota. The Lake Calhoun edition is the largest, kicking off with a “Frozen Friday” featuring the Cool School Plunge, the Executive Challenge, plunge ambassador Ian Leonard and fireworks (7 p.m.). The main event is Saturday, with additional activities including snow volleyball, an ice carving contest, a 5K walk/run and ice bowling. Forecast highs are in the upper 30s — is that a good thing? (10 a.m. Fri.-Sat. Check-in: 4-6:30 p.m. Thu.-Fri. or 10 a.m.-2 p.m. Sat. Thomas Beach, Lake Calhoun, Thomas Av. S. & W. Calhoun Pkwy., Mpls. J.P.



Red Dress Collection

The Red Dress Collection debuted at New York Fashion Week in 2003. Celebrities walked the runway in custom red dresses by designers including Vera Wang and Oscar de la Renta to raise awareness of heart disease in women. The Twin Cities version pairs Minnesota designers with local personalities to benefit the American Heart Association’s Go Red for Women campaign. Twenty designers including Christopher Straub, Caroline Hayden, Kimberly Jurek and Jennifer Chilstrom of Kjurek, George Moskal and Emma Berg have created one-of-a-kind looks for local notables — mostly television news anchors and radio personalities. The closest we’re getting to celebrity status are singer Kat Perkins of “The Voice” (who’ll also perform), MPR host Cathy Wurzer and Minnesota Viking Greg Jennings. Yep, there are some men in this year’s show — we’re guessing they’ll eschew red dresses in favor of crimson suits. (7 p.m. Sat. $25-$125. Loews Hotel, 601 1st Av. N., Mpls. J.P.