The silence has given rise to guessing games and conspiracy theories bouncing around on social media about what happened at the facility in the Sacramento Mountains, especially given reports that the FBI was involved.

The observatory, near Alamagordo, was evacuated last Thursday, reported the Albuquerque Journal and other local media outlets.

"Sunspot apologizes for the continued closure of the facilities," a statement on the observatory's Facebook page said on Sunday. "The Association of Universities for Research in Astronomy (AURA) is addressing a security issue at the National Solar Observatory facility at Sacramento Peak, New Mexico and has decided to temporarily vacate the facility as a precautionary measure.