The Mars rover Curiosity continues to scan the red planet for the building blocks of life, while a report released earlier this month shows that 60 billion planets — double the number previously estimated — may be habitable in the Milky Way alone. Then there’s the Roswell incident, which celebrates its 66th anniversary  Monday.

The anniversary received the Google Doodle treatment in an interactive game, as The Post’s Michael Cavna writes.

The “Roswell incident” refers to the July 8, 1947, Roswell Daily Record report of what was then believed to be a flying saucer retrieved on a Roswell, N.M., ranch. The UFO in question turned out to be debris from a test balloon that was part of an Air Force research project code-named MOGUL, according to an extensive report on the Roswell incident published in 1995 titled “The Roswell Report: Fact versus Fiction in the New Mexico Desert”. A 1997 follow-on to that report, “The Roswell Report: Case Closed,” provided further details regarding the claims of alien bodies found at the site. The report concluded that the bodies were most likely attributable to anthropomorphic test dummies used in high-altitude test balloon flights, a 1956 incident in which 11 Air Force members were killed, or a 1959 incident in which two members of the Air Force were injured. Then-Secretary of the Air Force Sheila Widnall wrote in the introduction to the follow-on report:

“I think that with this publication we have reached our goal of a complete and open explanation of the events that occurred in the Southwest many years ago.”

But, in 2011, a memo authored in 1950 started making the rounds online. The memo was sent to then FBI Director J. Edgar Hoover by Guy Hottel, head of the Washington, D.C., field office at the time. In the memo, Hottel describes the sighting of “flying saucers” in Roswell. The information, writes Hottel, was relayed to him by an FBI agent citing an Air Force investigator as his source.

The Hottel Memo, as it is now known, stirred the Roswell conspiracy-theory pot right back up again in 2011 when the FBI launched its online reading room “The Vault.” The Daily Mail published a report in April 2011 citing the memo and headlined, “The memo ‘that proves aliens landed at Roswell’ released online by the FBI.”

But an FBI report released in March 2013 outlines that the attention being paid to the report wasn’t the result of a new release or scoop, but rather fresh attention generated by the 2011 launch of The Vault. The memo, authored close to three years after the Roswell Incident, had been made public years earlier — in the late 1970s — well before the Air Force’s exhaustive reports on the Roswell incident in the 1990s, according to the FBI. The 2013 FBI report goes on to detail that the memo was deemed to be “simply a second- or third-hand claim that we never investigated.”  The bureau investigated some claims of UFO sightings for a few years after the Roswell Incident in 1947, but they stopped doing so four months after the Hottel memo, per the FBI write-up. Another one-page memo was released on the occasion of the Roswell incident, describing the storyline at the time and the news organizations clamoring to break the story.

Not surprisingly, the Hottel memo, according to the FBI, is the most popular document on The Vault site.

Whether you believe the FBI or not, the story of aliens landing on Earth reminded me of another Google doodle celebrating the first broadcast of the original Star Trek back in September.

The game celebrating the Roswell incident anniversary is more extensive than the Star Trek-themed game, offering longer gameplay as you work to send an alien home after he crash-lands on, of course, a ranch.

But if you’re in Roswell and desperate to see something besides stars and planes in the sky, you can look up during these dates and times in July to gaze upon the international space station. There are only humans up there. But who knows — maybe one day they won’t be alone.