Get a sneak peek at soprano Lauren Snouffer, scheduled to appear in Houston Grand Opera’s upcoming Show Boat, when she performs in A Baroque Christmas with Mercury in a joyful concert of seasonal treasures from the 17th and 18th century repertoire. The program includes Scarlatti's Christmas Cantata, Corrette's Noel Symphony No. 4 and Handel's Gloria with Antoine Plante at the podium. Here's some trivia for classical music fans: Handel's Gloria was probably composed in 1706, but wasn't performed until 2001 after it was found in a collection of his arias in the Royal Academy of Music's library in London. The piece has been called ''fresh, exuberant and a little wild in places, but unmistakably Handel.'' Sounds like the perfect Mercury piece.