WASHINGTON — The strange objects, one of them like a spinning top moving against the wind, appeared almost daily from the summer of 2014 to March 2015, high in the skies over the East Coast. Navy pilots reported to their superiors that the objects had no visible engine or infrared exhaust plumes, but that they could reach 30,000 feet and hypersonic speeds. “These things would be out there all day,” said Lt. Ryan Graves, an F/A-18 Super Hornet pilot who has been with the Navy for 10 years, and who reported his sightings to the Pentagon and Congress. “Keeping an aircraft in the air requires a significant amount of energy. With the speeds we observed, 12 hours in the air is 11 hours longer than we’d expect.” In late 2014, a Super Hornet pilot had a near collision with one of the objects, and an official mishap report was filed. Some of the incidents were videotaped, including one taken by a plane’s camera in early 2015 that shows an object zooming over the ocean waves as pilots question what they are watching. No one in the Defense Department is saying that the objects were extraterrestrial, and experts emphasize that earthly explanations can generally be found for such incidents. ...