An alien symbol is a recurring image in the CW science fiction series Roswell, New Mexico. According to Noah, it's a map.
As a kid, Max used to doodle the image on his notebooks and sneakers. On his twenty-first birthday (2011), Max "got trashed" and got the image tattooed on his back-right shoulder.
In 2008, Isobel draws the symbol on the gazebo during one of her blackouts with Rosa.
When the power in Roswell comes back after the blackout, it comes back in pieces that resemble an alien symbol before coming fully back up.
After Isobel blacks out and wakes up in the desert, the alien symbol is drawn in the ground around her.
When Wyatt is recovering from being shot, Jenna Cameron asks him to write down his version of the events of the shooting, but he doesn't remember. While they talk, he draws the alien symbol without realizing he's doing so and he doesn't know what it is. Jenna later asks Max about his tattoo, and when she shows him Wyatt's drawing, Max walks off.
After Isobel goes into the alien pod, Max touches the side of the pod and the alien symbol appears where his hand was.
Max and Michael go to Texas to visit the faith healer Arizona, who uses the alien symbol on her fliers. She doesn't really know about the symbol, but her associate Chiana tells Max about it. A woman used to live on their reservation, and she could heal with her hands, and the symbol "drew itself" around her such as in fire and water. The woman died around the time Max, Michael, and Isobel came out of their pods in 1997.
Noah tells Max that the symbol is a map to where they're from.