You might have spotted glowing orbs blitzing across the sky. For weeks, residents along the country’s Northeast corridor, from New Jersey to Maryland, have reported seeing drones or other aircraft — some purportedly as big as cars — speeding overhead. The FBI has received thousands of calls about the drones.

On Monday, federal officials said they’ve found no national security or public safety risk, adding that many of the sightings appear to be a combination of commercial and hobbyist drones, as well as manned fixed-wing aircraft and stars mistakenly reported as drones.

However, the aerial phenomena have fueled paranoia nationally and locally. Last week, former Maryland Gov. Larry Hogan said in a social media post he saw what he believed were “dozens of large drones in the sky” above his Davidsonville house Thursday night.

“With immense respect, Mr. governor,” replied Matthew Cappucci, a local meteorologist, “this is the constellation ‘Orion.’ ... The stars will be in a similar place tomorrow.”

Here’s what you need to know about the drone sightings.

Why is there so much concern about the possibility of drones?

State and local officials across the Northeast have fielded dozens of complaints from residents who say the drones scare them.

The fear of unidentified flying objects isn’t new and is partly rooted in Americans’ concerns about espionage, technological threats and other forms of foreign interference. Last year, residents across the country exhibited a similar hysteria over a Chinese weather balloon that some believed was a specter of foreign intrusion. The balloon floated over a large swath of the country before being shot down.

This time, some lawmakers, such as New Jersey Rep. Jeff Van Drew, have stoked fear among residents by linking the drones to foreign adversaries. Van Drew said in a statement released last week he believed the drones were sent from Iran and “expertly navigating around areas with radar coverage.” The flying objects, he continued, should be shot down.

Pentagon deputy press secretary Sabrina Singh rebutted Van Drew’s statement Wednesday and said the drones were not “the work of a foreign adversary or a foreign entity.” She also said the drones were not from the U.S. military.

What have federal and state investigators said?

On Monday, multiple federal agencies released a joint statement saying they’ve investigated many of the reported sightings and believe the flying objects are benign.

“Having closely examined the technical data and tips from concerned citizens, we assess that the sightings to date include a combination of lawful commercial drones, hobbyist drones, and law enforcement drones, as well as manned fixed-wing aircraft, helicopters, and stars mistakenly reported as drones,” reads the statement. “We have not identified anything anomalous and do not assess the activity to date to present a national security or public safety risk over the civilian airspace in New Jersey or other states in the northeast.”

The statement echoes a similar message last week from White House National Security Council spokesperson John Kirby. “We have no evidence at this time that the reported drone sightings pose a national security or a public safety threat or have a foreign nexus,” he said in a media briefing.

Maryland Gov. Wes Moore previously said in an email that state officials are “aware of the reports of potential unmanned aerial system sightings and are working closely with federal authorities.”

New Jersey Gov. Phil Murphy said the drones have been spotted near notable areas, including the Picatinny Arsenal, a military manufacturing and research plant. But after he convened officials with the state and federal Homeland Security and law enforcement agencies, he said, “There is no known threat at this time.” The FAA imposed a flight restriction above Picatinny until the end of Dec. 26 as officials investigate the sightings.

In the joint statement on Monday, officials said drone sightings near or over military instillations are not new, but the Department of Defense “takes unauthorized access over its airspace seriously.” Local commanders are working to ensure “appropriate detection and mitigation measures in place,” the statements reads, and coordinating with state and local law enforcement as needed.

Are drone operations legal in Maryland?

In Maryland, drones are largely permitted for commercial and recreational use. Commercial pilots must pass the FAA’s aeronautical knowledge test to obtain a certificate for drone operations. Hobbyists need to pass a separate FAA test.

Airspace within five miles of Martin State Airport and seven miles of Baltimore-Washington International Thurgood Marshall Airport, though, is restricted. Airspace within fifteen miles of Ronald Reagan Washington National Airport — which extends to some parts of Maryland — is also locked. Drone operators must secure authorization from the FAA to operate drones in these boundaries.

The state and federal government can enact laws or temporary orders to prohibit, restrict or regulate the testing or operation of drones. On Saturday, ahead of the Army-Navy football game in Landover that attracted high-profile politicos including President-elect Donald Trump and Moore, the FAA implemented a temporary flight restriction around Northwest Stadium for the day.

“Drone operators need to know that we take seriously any incursion in the restricted airspace around the Army-Navy Game,” U.S. Attorney Erek L. Barron said in a statement. “Such incursions threaten the safety of those involved. We will investigate and prosecute anyone who violates the no drone zone.”

What penalties exist for unlawful drone operations?

Unregistered drone operators may be subject to a fine of up to $27,500. They can also open themselves to criminal penalties, including imprisonment for up to three years and fines of up to $250,000, according to the FAA.

Can you tell a drone from a plane at night?

A light in the sky at night can easily be misinterpreted, according to John Slaughter, director of the Unmanned Aircraft Systems Research and Operations Center at the University of Maryland.

“You can’t just walk outside and say, ‘Oh, that’s not a drone,’ or ‘That is one.’ All you can really factually say is, ‘I saw a light in the sky,’” Slaughter said.

Planes and helicopters all have flashing lights and typically at least one red anti-collision light, often two. They also sport navigation lights, which are steady, red- and green-colored lights like the ones found on boats. Many will also have flashing white strobe lights at their wingtips. And they have bright landing lights.

Drones flying at night are only required to have one bright, anti-collision light that’s visible 3 miles away. But drone owners can add other lights, so some have more than one. Drones are smaller, so when they have multiple lights they are close together, but at night it’s often not possible to figure out precisely how far away they are.

“A light is just a bright point,” Slaughter said. “And it might be 100 yards away, it could be literally 40 miles away, and it looks the same.”

Associated Press reporters John Seewer and Mark Scolforo contributed to this report.