Sprinkle gelatin over Midori in a small saucepan and let soften for 1 minute.

Heat the gelatin and Midori mixture over low heat, stirring, until the gelatin is completely dissolved. Let cool.

Puree honeydew, sugar, and lemon juice in a blender.

With the blender motor running, add the cooled Midori mixture in a steady stream.

Transfer the honeydew mixture to a metal bowl set in a larger bowl of ice and cold water.

Stir until the honeydew mousse reaches the consistency of raw egg white.

Remove the metal bowl from the ice, stir in yogurt, and let the honeydew mousse stand.

Sprinkle gelatin over Port in a small saucepan and let soften for 1 minute.

Heat the gelatin and Port mixture over low heat, stirring, until the gelatin is completely dissolved. Let cool.

Puree cantaloupe, sugar, and lemon juice in a blender.

With the blender motor running, add the cooled Port mixture in a steady stream.

Transfer the cantaloupe mixture to a metal bowl set in a larger bowl of ice and cold water.

Stir until the cantaloupe mousse reaches the consistency of raw egg white.

Remove the metal bowl from the ice and stir in the yogurt.

Layer the honeydew and cantaloupe mousses in a 2-quart glass bowl or 8 dessert glasses, chilling for 5 minutes between layers.

Chill the completed mousse for at least 2 hours or overnight.

Garnish with melon wedges before serving.