The orb's segmented pedestal, which looked as if it might have come from the bridge of a science-fiction starship, added to the mystery. And an illuminated floor, not directly visible in the most widely circulated images, intensified the dramatic underlighting. Critics of Mr. Trump, some of whom seem eager to see something nefarious in anything he does, appeared especially agitated. Some projected onto the images their dismay about Mr. Trump's playing down of human rights and about the authoritarian Egyptian and Saudi governments. Bill Kristol, a prominent conservative critic of Mr. Trump, likened the group to the conclave of witches in "Macbeth."