Bryce Harper changed the complexion of the Nationals’ NLDS against the Cubs with a home run in the eighth inning of Game 2. (John McDonnell/The Washington Post)

Maybe something changed, even something big, on Saturday night as the autumn moon rose over the right field stands to get a glimpse of what, far down on planet earth, was causing all that ruckus down at Nationals Park, a place that seldom raises it voice until the heavens take note.

Within a matter of perhaps 15 minutes of lunacy, Game 2 of this National League Division Series changed utterly, from what seemed like an almost certain Chicago Cubs victory to a stunning, ground-shaking, 6-3 Washington Nationals win.

Eighth-inning home runs, first a titanic one by Bryce Harper to tie the score, then a three-run wall-scraping thriller by Ryan Zimmerman to win it, tied this series at a game apiece, but with enormous baseball gravitational pull suddenly on the Nats’ side just when such cause for hope was least expected.

Harper’s homer was a truly special force-of-nature thing. Celestial orbs don’t blink. But if there had been a man in that moon, he might have been forgiven for flinching. Instead, Harper’s blast wasn’t headed toward space, just aimed directly at a picture of Max Scherzer that stands more than 500 feet away on the right field concourse.

Neither Scherzer’s blue nor brown eye was in danger as the blast off Carl Edwards Jr. landed deep in the second deck. At that moment, a stadium known for sanity and civility to the point of cerebral detachment went out of its mind and remained in that state, perhaps learning a lasting lesson about how towns, their teams and crowds can link arms and voice to take possession of a game.

“He hung a curveball. It happens in this game. C.J. wanted to hit the plate with it,” Cubs Manager Joe Maddon said. “It didn’t happen.”

Instead, Harper happened. “Why not? Swing as hard as you can,” Harper said of his first extra-base hit since missing 42 games after injuring his knee on Aug. 12. “Pretty good moment.”

The blast, following a leadoff pinch-hit single by Adam Lind, was of such force — both physical and symbolic for a team that has been frustrated, in one form or another, for the last six seasons — that the packed house of 43,860 knew its meaning as the ball was still figuring out its downrange landing coordinates.

“Harp’s known for his big moments,” Nationals Manager Dusty Baker said. “He blasted that ball a ton. . . . Baseball’s a daily game, but it’s also a game of momentum. Going to Chicago for Game 3 [on Monday] with Surge pitching for us — we feel very confident about that . . . [meaningful pause] . . . after tonight’s game.”

“Surge” would be the traditional Baker mispronunciation of Scherzer’s name. Scherzer says Baker calls him “Surge” half the time and “Scherz” the other. Whichever it is, Scherzer, who may win his third Cy Young Award this season, and who is one of the greatest pitchers of his era, is exactly what any team, even the newly proud Cubs, don’t want to see in a potentially “pivotal” Game 3.

Next, after a walk to Anthony Rendon, who had homered in the first inning, and a single by Daniel Murphy, who just might have been praying in the on-deck circle when Harper was at bat, the stage was set for a moment that proved that Baseball Feel Good in Washington could be raised to a previously unknown power.

Zimmerman, who has been the personal pick-on-Zim pigeon of Maddon, hit a towering flyball to left field. All year, Zimmerman has been trying to heighten his “launch angle” with almost no success, despite his 36 homers and 108 RBI. What a terrible time to suddenly hit a ball too high!

What followed, as the crowd waited with screams stuck in its throat for what seemed like 10 seconds, was one of the most fortunate, wind-aided, destiny-kissed three-run homers you’ll ever see, presented by the kind elements to one of the most deserving honorable men in baseball. When Ben Zobrist jumped and came down with nothing as the ball barely escaped his glove, the roof of this South Capitol Street joint almost blew off.

Nationals danced around the bases and outside their dugout, bellowed to each other, hugged and gave perfect impressions of exactly what they were — a team on the verge of likely humiliation that had been released from baseball playoff bondage by two swings by two of Washington’s favorite athletes.

“I didn’t know,” Zimmerman said of his long wait for the ball to land. “I hit it good but really high. The wind was blowing out pretty much the whole night. Maybe I got a little lucky, who knows?”

“It couldn’t have happened to a finer guy,” Baker said.

Asked about his favorite all-time homer, Harper ignored his own and said, “Zim’s ranks No. 1 for me. . . . Mr. Walkoff — sittin’ right next to me.”

This NLDS has now been changed, whether utterly or not we’ll soon discover. But a Nationals team, locked in the scary ice of a horrific team-wide slump, has suddenly exploded, smashing out of its frozen demoralized state to even this series at a game apiece. After scoring one run on just four hits — f-o-u-r — in the first 16 innings of this series, the Nats got five runs and 10 total bases in one frame.

Adding salt for the Cubs, Maddon had lefty Mike Montgomery warm and ready to face Harper but didn’t bring him in. When he finally waved Montgomery in to face Murphy, who singled, the ballpark was in control of events. “Hung a change-up,” Maddon said of the Zimmerman homer. “For me a perfect situation to try to get the ball on the ground (for a Zimmerman double play.) Didn’t happen.”

Didn’t Joe say that before?

The measure of what a body blow this Nats comeback may be to the Cubs is the length to which Maddon repeated how wonderful everything was in his world. “I could not be happier,” he said of his team’s efforts and such irrelevancies. “Everything has been wonderful,” he added, not mentioning any final scores, like, you know, a 6-3 that looked like a mortal 3-1 lock for the Cubs.

Strange things happen in October, matters that almost require a big fat moon gazing down to ensure the marvelous madness. “Baseball is contagious,” Zimmerman said. “Slumps are contagious. So is hitting. That’s why Harp’s homer was so important.”

How important? Perhaps even the story arc of a Washington franchise, when we have the luxury of hindsight, will be seen to have changed.

For two nights the Nats were in the kind of classic October nightmare that, once begun, is seldom escaped until the offseason carries the miserable team off into winter, drenched in self-flagellating torment. Harper did what sports heroes do. He flipped the narrative, the mood, in one crash-flash of a moment. Zimmerman’s towering fly seemed to ride its lingering shockwaves.

For months, the Nats have waited to get healthy and get their “real team,” their real lineup back together. Those blasters, hard as it may be to remember now, scored 10 or more runs 21 times this season.

On consecutive nights in Colorado, they won 15-12, 11-4 and 16-5 against a Rockies team good enough to make the playoffs. One night they scored 23 runs against the Mets as Rendon went 6 for 6 with 10 RBI. They didn’t just win, the rampaged with scores like 13-3, 12-3, 18-3, 14-4, and 15-2.

If Trea Turner didn’t hit for the cycle, then Murphy drove in five runs — four different times. Zimmerman hit two homers in a game — seven times. And Harper was the best of all, on pace for 42 homers, 125 RBI and a .327 average when he was hurt.

“Bryce looks like he’s on the way,” Baker said, planting a seed. “The longer we play, the better Bryce will be.”

And how long will that be? Until Harper, then Zimmerman swung, that time frame seemed like it might be just a very few days. Now, you never know.

Might be a while. That moon isn’t full.