There are people who believe that the moon landing never happened, that the astronauts in the footage all the world saw were actually bouncing around on a soundstage hidden away somewhere. But they aren’t making our laws, they aren’t invited on TV to discuss their perspective, and they don’t have the ability to influence millions.

Yet there are people who deny the truth of what happened in Washington on Jan. 6, despite all the video, all the contemporaneous reports, all the guilty pleas, and all the testimony. And they have a lot more power.

Tuesday’s first hearing of the select House committee investigating the insurrection, with vivid testimony from four police officers who stood against a mob of President Donald Trump’s supporters overrunning the Capitol in an attempt to overturn a presidential election, should put at least some questions about that day to rest.

Still recovering from their physical and mental injuries, the officers seemed particularly incensed that the truth of what happened that day is denied by so many on the right, from Trump himself on down.

“To me, it’s insulting, just demoralizing because of everything that we did to prevent everyone in the Capitol from getting hurt,” said Capitol Police Sgt. Aquilino Gonell about the effort to minimize what happened that day, including by Trump. (“It was a loving crowd,” the former president told Post reporters Carol Leonnig and Philip Rucker, “There was a lot of love. I’ve heard that from everybody.”)

Gonnell also addressed the various conspiracy theories propagated by some very high-profile figures on the right, claiming that the insurrection might have been a false-flag operation. “It was not antifa,” he said. “It was not Black Lives Matter. It was not the FBI. It was his supporters that he sent them over to the Capitol that day.”

“The indifference shown to my colleagues is disgraceful,” said D.C. police officer Michael Fanone, slamming his fist on the table. “Nothing, truly nothing, has prepared me to address those elected members of our government who continue to deny the events of that day.”

That denial takes various forms. Some, like Trump, assert that the riot was no big deal (“By and large it was peaceful protest,” said Republican Sen. Ron Johnson of Wisconsin). Others say that, while it was certainly bad, it doesn’t have anything to do with any larger political forces and should be put behind us.

But the truth is that there was nothing isolated about the event. Those rioters came to Washington at Trump’s behest. They assaulted the seat of our government in an effort to prevent the final certification of an American presidential election. And to this day, most of the GOP continues to stoke the fires of racial resentment and contempt for the democracy that made it possible.

One of the few exceptions in the Republican Party, Rep. Adam Kinzinger (Ill.) dispatched the bad-faith argument so many in his party made that any investigation of Jan. 6 should also spend time talking about protests last summer against police misconduct, during which violence broke out:

Some have concocted a counternarrative to discredit this process on the grounds that we didn’t launch a similar investigation into the urban riots and looting last summer. Mr. Chairman, I was called on to serve during the summer riots as an Air National Guardsman. I condemn those riots and the destruction of property that resulted. But not once did I ever feel that the future of self-governance was threatened like I did on January 6. There is a difference between breaking the law and rejecting the rule of law, between a crime, even grave crimes, and a coup.

That is the heart of what made January 6 so threatening: Not just the physical violence, but the assault on the American system.

Here’s what will happen now. First, those on the extreme right — both individuals and those in fringe media outlets — will attack the officers who testified Tuesday, claiming that they’re impostors or liars or liberal Democrats only seeking to harm Trump.

Next, those claims will soon be echoed in slightly more presentable form on outlets with broader audiences. Hosts on Fox News and the like will disseminate some new conspiracy theory about these officers, presented as “just asking questions.” Inevitably, the officers will be targeted with a torrent of hate and threats.

While many Republican officeholders will try to avoid talking about Jan. 6 at all, others who see how their party base and the conservative media are responding will continue to stand against the truth in one way or another. Some may indulge conspiracy theories without completely embracing them. Others will follow the lead of the House Republican leadership and say nonsensically that the insurrection was Speaker Nancy Pelosi’s fault.

And a month or a year from now, you’ll see some new poll with alarming figures about how many rank-and-file Republicans believe the insurrection was a good thing, or that those who carried it out were legitimately expressing their grievances over an election so many in the GOP still say was stolen, or that the whole thing has been blown out of proportion anyway.

The truth got a boost from those four officers. But in trying to make sure the American people understand what really happened, they have an uphill climb.