Cenacle or Cenaculum is the place on Mount Zion in Jerusalem where our LORD’s Supper took place. It is across town from Gethsemane and Calvary. Originally a rooftop deck (which were used for outdoor meals in that hot climate) it is now at ground level, and was roofed over with Gothic vaulting in the 1200s. The site was used as a mosque until 1967, and is now Israeli state property.
As JKRH said, the term simply means dining room (in Latin).
As to the other 2 items: neither the “Cross in the Sky” nor a new planet are Church teaching, because neither is true. There is no way that comets can form a cross, because the tails of comets will always point away from the sun and thus be parallel. And if there were a new planet in this solar system, the gravitational effect of it would have been observed for some years now.
God Bless and ICXC NIKA
