ANKARA, Turkey—A metal monolith that mysteriously appeared and disappeared on a field in southeast Turkey turned out to be a publicity gimmick before a government event Tuesday during which Turkish President Recep Tayyip Erdogan announced a space program for the country. The three-meter-high (about 10-foot-high) metal slab bearing an ancient Turkic script, was found Friday by a farmer in Sanliurfa province. It was discovered near the UNESCO World Heritage site of Gobekli Tepe, which is home to megalithic structures dating to the 10th millennium B.C., thousands of years before Stonehenge. However, the shiny structure that bore the inscription “Look at the sky, you will see the moon” in the ancient Turkic Gokturk alphabet, was reported gone Tuesday morning, adding to the mystery. An image of the monolith was later projected on a screen as Erdogan presented Turkey’s space program during a televised event. “I now present to you Turkey’s 10-year …