UFOs don't necessarily mean aliens, as they have been associated with in pop culture, but they definitely do mean something weird is going on.

A recent report by The New York Times highlighted the prevalence of UFO sightings among pilots and explained what the Defense Department has to say about them.

Lt. Ryan Graves, a 10-year navy pilot, witnessed these objects repeatedly during the USS Theodore Roosevelt's 2014-2015 training exercises on the east coast.

He spoke with The Times about his experiences, which he reported to both the Pentagon and to Congress.

"These things would be out there all day. 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."

According to The Times,

"experts emphasize that earthly explanations can generally be found for such incidents."

The new classified guidance put out by the Navy after the Roosevelt sightings on how to report these "unexplained aerial phenomena" would seem to indicate that someone was beginning to take the reports seriously.

Navy spokesperson Joseph Gradisher stated that the new reporting guidance was released after those sightings.

"There were a number of different reports. We don't know who's doing this, we don't have enough data to track this. So the intent of the message to the fleet is to provide updated guidance on reporting procedures for suspected intrusions into our airspace."

Leon Golub, a senior astrophysicist at Harvard-Smithsonian Center for Astrophysics, weighed in on the possible causes of the sightings as well. He didn't completely discount the possibility that the objects were extraterrestrial, but noted that the possibility was highly unlikely.

"There are so many other possibilities — bugs in the code for the imaging and display systems, atmospheric effects and reflections, neurological overload from multiple inputs during high-speed flight."

Another seemingly-likely possibility is that the objects are part of an advanced unmanned drone project, but there are multiple things making this less likely to be the answer.

The objects have been reported to move in ways that don't match the capabilities of our current flight technology: appearing at various altitudes from sea level up to 30,000 feet, rapid acceleration and deceleration, followed by rapid jumps to hypersonic speeds.

Lt. Graves and other squadron members from the Roosevelt were further convinced that these weren't just experimental drones after one of them had a near miss with one of the objects during a flight.

Graves was back on base at Virginia Beach when he ran into a pilot on his way back from a flight. Graves said the man was visibly upset and told him:

"I almost hit one of those things."

Believing that a government-run drone project would be aware of their squadrons maneuvers on the East Coast and would therefore avoid their airspace so as to avoid such possible collisions, the squadron began to discount that possibility.

Some Twitter users offered their own theories.

Others were just intrigued by the story.

Of course, there were X-Files references galore.

Some people shared personal or family stories of UFO sightings.

After leaving Port at Virginia Beach for the Persian Gulf, the crew says that the sightings became less frequent as they got further from the US.

While nobody is officially claiming to know what these objects are, it seems clear that there is something that pilots are seeing and encountering while in US airspace.

The Defense Department continues to insist there may well be a perfectly reasonable—and terrestrial—explanation for the sightings.

Until that explanation is found, though, there will still be those holding out hope for extraterrestrial contact.