The FBI shut down a space observatory near Roswell, New Mexico more than a week ago, and still no one knows why

• Solar observatory in New Mexico shut down and evacuated

• Local officers say 'FBI was here'

• Theories range from aliens to solar flares to Russian hackers

Last Thursday, employees at the Sunspot Solar Observatory in remote New Mexico rang local law enforcement officers and asked them to come in.

Within hours, the observatory was evacuated, and one officer confirmed to the media that "the FBI had been there".

None of the employees have returned since, and no one has publicly identified the reason why the observatory was evacuated.

All the Association of Universities for Research in Astronomy - AURA - which runs the observatory, would say was that the facility was temporarily evacuated while it addressed "a security incident".

Stranger and stranger, a nearby post office was evacuated. An official told a local ABC affiliate that "he did not know who ordered the postal workers to leave".

And about 2km away, another NSO facility, the Apache Point Observatory, remains open.

More than a week later, the observatory is still closed for business. And "more than a week" is a long time to let conspiracy theorists froth and bubble.

First, for those not familiar with New Mexico, here's why Sunspot is of particular interest:

Roughly 200km from the site of the most famous alien conspiracy theory of all is just too much of a coincidence for ET hunters.

Among the other theories:

• A giant solar flare is coming to wipe out Earth's power

• Chinese or Russian hackers have done something nefarious

• EMP weapons testing

• Terrorist cells

• Portals to other dimensions

Security isn't exactly the type you see in the movies when an alien presence is contained on Earth. Just a single piece of tape, according to this local news report:

Otero County Sheriff Benny House told BuzzFeed News officers also saw a Black Hawk helicopter flying overhead, but added there was a US Air Force base nearby.

All of which is pretty much the mother lode for online groups looking to spice up their lives.

Even conservative British papers like The Independant can't resist the story.

The closest anyone has got to an answer is Gizmodo, which quoted Frank Fisher, a public affairs officer at the FBI's Albuquerque Division as saying the research group is indeed still "addressing a security issue".