The 50th anniversary of the first Moon landing has brought both celebrations, confirming it as one of the pinnacles of human achievement, and puzzlement about why we haven't been back for so long. It's also giving scientists and engineers a chance to explain to the world just how ridiculous Moon landing conspiracy theories are, although some media outlets aren't helping by posting stories whose headlines suggest there's actual doubt.

Geologist Professor Trevor Ireland from the Australian National University is doing his bit to turn the tide of ignorance by explaining just how difficult faking the 380 kilograms (836 pounds) of rocks the Apollo astronauts brought back from the Moon would have been.

Although the lunar rocks contained no elements unknown on Earth, this doesn't mean they could have been produced by bombarding some Earth rocks with radiation in a vacuum

“The rocks are all really old, mostly 3.8 billion years, and they have never seen water," Ireland told IFLScience. "The few terrestrial rocks of that age have been stuffed around.”

As with Earth rocks, ages were identified using radioactive isotopes. Most importantly, the older a rock is, the more of its initial uranium will have turned to lead. Uranium is easily incorporated into crystals called zircons as they form, but Ireland told IFLScience, “We haven't figured out how to get lead inside zircon crystals.” The idea that 50 years ago NASA could make zircons with enough lead inside to look old, that could still be fooling geologists with far more advanced equipment 50 years later, is fanciful.

Ireland has a particular stake in the issue beyond defending the truth. While too young to have been part of the first phase of moonrock analysis, much of it was done by his predecessors at ANU, who had state of the art equipment thanks to being one of the newest institutes at the time, and included several experts on the world's oldest rocks.

Gaining the hotly contested honor of first access to the samples had a price, Emeritus Professor Ross Taylor, recounts. With the world's media clamoring for results, he worked 20 hours a day on the Apollo 11 rocks so he could make fresh announcements at daily press conferences.

Around 200-300 geologists were contracted by NASA to study samples from at least one of the six successful missions. “To this day, we continue to analyze the Apollo lunar rocks and they still have surprises for us,” Ireland said in a statement. He estimates 700-900 additional geologists have examined the rocks in subsequent decades, each of whom would have spotted a fake with ease.

The discovery in 1982 of the first meteorite of lunar origin also matched the Apollo samples precisely.

Plus, as Ireland pointed out to IFLScience, scientists are the worst people to try to recruit to a large-scale conspiracy, because they are always seeking opportunities to prove each other wrong.