Natalie Portman encounters Chris Hemsworth for the first time in this sneak peek. By Kara Warner Chris Hemsworth in “Thor” Photo: Paramount Pictures Attention “Thor” fans! By the good graces of otherworldly Asgard, Paramount Pictures has gifted MTV News with an exclusive new clip from the upcoming and highly anticipated “Thor.” For those who’ve been watching and re-watching the trailers , the featured scene will be slightly familiar. The clip opens with Jane Foster (Natalie Portman), Professor Andrews (Stellan Skarsg