There are many milestone movies that resonate with a generation, but none more so than Hollywood director Steven Spielberg’s 1982 film about a lost extra-terrestrial and the little boy he befriends on Earth.

Some even go so far as to say E.T. the Extra-Terrestrial is the most significant pop culture film in history, leaving an unsurpassed legacy.

Speaking at the pointy end of its 40th anniversary celebrations – which have been running now for several weeks – child star Henry Thomas (who played young Elliott) tells CNN he initially didn’t understand the little alien who came to live in his house.

“I remember as a kid, you know, I was really into Star Wars and Indiana Jones … I was given a script and I read it and I thought, there’s no laser fighting? There’s no starships, or battles, or fights?”

“But it works. It works somehow,” the 51-year-old said.

“[E.T. was] a lot of people’s first experience of seeing a film in the theatre … and so it’s special and they’re showing it to their kids.

“And, you know, it’s kind of become our generation’s Wizard of Oz,” he told one US news radio network during a week of interviews.

Forbes says E.T. broke records and grossed $US794.9 million ($1.2 billion) at the box office against a $US10.5 million ($16.5 million) budget.

Hugely popular Drew Barrymore, now with her own chat show, as Gertie as she hands him her potted plant and kisses him goodbye. Photo: AAP

It’s not just the stars talking up the movie this week …. there’s also the merchandise.

On Friday, Australia Post will release an official licensed stamp pack containing 12 self-adhesive stamps.

The Perth Mint is selling a one-ounce (28 gram) silver collector coin worth $160, and with Halloween celebrations on Sunday, it’s not too late to order an E.T. mask online for $77.

But wait, there’s more.

Major retail chains including JB Hi-Fi will start selling a 4K Ultra HD limited-edition DVD, packaging it up with booklets, art cards, a Spielberg featurette and 45 minutes of never-before-seen bonus content on November 2.

And, to top it off for free, Thomas’ emotional audition tape (where he thought of his dead dog to make himself cry) recently resurfaced and went viral online.

The improvised scene saw him conjuring real tears, with Spielberg famously – off camera – saying: “OK, kid: You got the job.”

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Why the movie has endured for four decades

Many a university, scholar and classroom have unpacked the messaging in E.T. and why it resonates on so many levels.

From the filmmaking, to the storyline and music, to that delightful blend of suburban Los Angeles children meeting supernatural creatures on the big screen, it created a new benchmark for the sci-fi genre in Hollywood.

The story goes that Elliott is the middle child in a family whose father has just left his mother and heads off to Mexico with a new girlfriend. His mother is trying to work a job and feed three kids on her own.

Spielberg brings the heartache of loneliness into the home, and when Elliott sees “something” in the forest behind their house, he searches, and lures the alien to his backyard using a packet of M&Ms.

He shows him to his siblings, Michael and Gertie, hiding in his upstairs bedroom wardrobe. Elliott makes them promise to give him “ultimate power” as he and E.T. start to feel each other’s emotions and thoughts.

Elliott wants to keep him. He wants him as a friend.

Gertie teaches him how to speak from a TV alphabet show, and before long, E.T. tells the kids to scavenge around for household items that can generate a signal to his spaceship.

He wants to “phone home”.

But time is against them. E.T. starts to die, and simultaneously so does Elliott.

Suddenly, their home is raided by federal government officials who have been secretly watching them, and the much-loved alien is taken by adults with fears from the kids he’ll just be injected and “cut open”.

The classic rescue story then comes into play, and E.T. eventually gets back to the redwood forest in one of the classic Hollywood chases.

The farewell scene is still full of magic: Elliott tells him he loves him, to which E.T. replies that even from another galaxy, “I’ll be right here”.

Although Thomas hasn’t watched the film in 20 years (he said he can’t watch himself on screen), he tells CNN he understands why the movie has endured.

“It speaks to our universal human compassion,” he said.

“And we all have that. We all have the nurturer inside of us, right? So I think it speaks to that. It brings us back to being young.”

Caseen Gaines, who recently published E.T. the Extra-Terrestrial, The Ultimate Visual History (Insight Editions, September 2022), says it’s “such an important film … not only among Spielberg’s body of work, but to cinema history”.

“I have written about a number of significant moments in popular culture history, and it’s hard to think of a moment more significant than E.T.,” he tells space.com

” I think the film still resonates because of how heartfelt it is.

“It still feels incredibly personal and intimate, like we are being let in on Elliott’s secret and lucky to be an observer to this special relationship he has with a visitor from outer space.

“It almost doesn’t feel like you’re watching a film, but an extraordinary, yet believable, slice of life.”