LOS ANGELES - The moon is the world’s largest and brightest object in the night sky, and now Taco Bell is using it as a marketing campaign — that the whole world can see.According to Taco Bell, the lunar phase of the moon will resemble a taco on May 4, and the fast-food chain will give fans a free crunchy taco all day on the app or online.RELATED: Chipotle giving away 250,000 free burritos to US health care workersThe company is affectionately calling the moon’s half-moon shape the "Taco Moon," and more than 20 markets around the globe, including the U.S., will be able to participate in the offer."Taco Bell has been an established brand in the U.S.