- He was reluctant to kill his old master. He says straight up that Obi-Wan "should not have come back." He knew where Obi-Wan was hiding on Tatooine, but he didn't hunt him down — not just because of the canon reason that his memories of Tatooine were too traumatic (because he could still have just hired someone else to off Obi-Wan), but also because he didn't really want Obi-Wan dead. Vader duels Obi-Wan as a kind-of respected opponent. When Obi-Wan stops fighting, Vader hits him with what he expects is a non-lethal blow; he didn't expect it to actually finish Obi-Wan, hence his confusion at the empty robes.
- He wasn't sure it even was Obi-Wan; it might have been a trap. When he senses Obi-Wan's presence, he says he hadn't felt it in a long time; it might have been so long, he might not have been sure what he was sensing. He knows it's possible to make a Force Doppelgänger. Compared to their duel in Revenge of the Sith, Obi-Wan spends less time trying to convince Vader that there's still good in him; he even addresses Vader as "Darth", as if to acknowledge that Anakin Skywalker is dead to him, something Vader doesn't think Obi-Wan would ever do (he underestimated how far Obi-Wan believes he's fallen). Vader checks the robes to see if the trap is about to spring.
- He's just toying with Obi-Wan. He wants to show Obi-Wan how much better he's gotten ("I was but the learner; now I am the master.") His rather reserved lightsaber combat is reminiscent of what he does to Luke in The Empire Strikes Back; he could land the killing blow at any time, but he wants to show his opponent how much more powerful he is.note When Obi-Wan stops fighting, Vader is disappointed that Obi-Wan has given up and kills him in disgust; it's only after this that Vader reflects on Obi-Wan's line, "If you strike me down, I shall become more powerful than you can possibly imagine." Then he fiddles with the empty robes thinking about what Obi-Wan meant by that.
If you're going to argue that there were TIE fighters flying around above the Death Star to meet the Rebels, the supplemental material was quite clear that this had nothing to do with Tarkin. That was Darth Vader's personal fighter squadron; Vader saw what Tarkin couldn't, and not having the hierarchical clout to convince Tarkin to change his mind in time, he just did what he could with what he had.
If you're going to argue that the Death Star had a crapton of surface lasers to deal with a group of small manned fighters — which, in the film, actually do a great job of blowing up several rebels who are not Luke Skywalkernote — well, it's not enough. First, those surface lasers cannot aim at fighters who get too close to the surface itself — indeed, the whole point of ducking into the trench is to avoid the surface lasers. Second, the surface lasers are fixed to the Death Star and need to wait for enemy fighters to approach it. They can't deal with anything happening beyond their range — like, say, travel a bit further out and catch Han and Chewie on the Falcon ambushing Vader and giving Luke a clear shot.
If you're going to argue that Obi-Wan's Force ghost in The Empire Strikes Back clearly says that he cannot interfere with the living world... well, he's just convincing people to do what they were always going to do. He can't make Luke put away his targeting computer and trust the Force, but Luke was already inclined to do it in the back of his mind. Similarly, he can't make Tarkin rely solely on his surface lasers, but Tarkin was already so cocky that it wouldn't have taken much to convince him. You can argue whatever you want, but this is WMG — there's almost always room for it!
- He intentionally lost the Battle of Yavin. The above WMG goes into detail about the implications of Tarkin relying entirely on the surface cannons and not sending out a single TIE fighter to deal with a pretty small Rebel attack force. (Remember, the ones we see up there were Vader's personal squadron.) Sure, the surface cannons took out most of the Rebels, but they left three of the most important pilots: the Rebels' Ace Pilot Wedge Antilles, ambush pilot Han Solo on the Falcon, and of course Luke Skywalker.
- He may have actually sabotaged the Death Star. It's not like anyone would have been able to stop him. He could easily get a droid to do things he's not technically competent to do. He may even have been entirely responsible for the destruction; Luke's torpedo wouldn't have done anything, and Tarkin worked the timing to make it look plausibly like Luke did it.
- He was the one who leaked the Death Star plans to the Rebels. (This requires Rogue One to have been an incomplete account of how the Rebels stole the plans.) If we assume that Tarkin personally blew up the Death Star, obviating the need for a weakness in the Death Star, he may have (unwittingly) set up the second Death Star to have a real vulnerability from their solution to a problem that didn't exist to begin with.
Tarkin was a bit too conservative in maintaining his facade, which led to a lot of the good guys getting killed. He did save many of the important people, but he started to get very guilty about all the blood on his hands, especially what with blowing up Alderaan. That's why he refused to evacuate the Death Star when he knew it was going to blow up.Again, a difficult theory — much easier to pin the "secret Rebel" label on one of the incompetent underlings from The Empire Strikes Back like Admiral Ozzel or Captain Needa.note And you'd also have to throw out the Death Star novel, which suggests that Tarkin is so proud of the Death Star that he's kind of got a thing for it. But... interesting.
His escape pod barely survived the Death Star's explosion, and he was injured pretty badly. But he lived! He just lost his memory in the process, so he doesn't know who he is. That's some powerful Fanfic Fuel, by the way. He could be a Mad Scientist! Or a Coruscanti rapper named Tar-Pac! Or could rediscover his memories in The Tarkin Identity! Or he's living the life of a rich lounge lizard on some resort world somewhere, attended to by nubile Green Skinned Space Babes! (Actually, he can keep his memory for that last one.)
If you're going to argue that there's no way he could have made it off the Death Star in time, given the shot of him on the bridge right before it blows up, well... it was a really close call! Or that shot used a body double.
To make this work, we've got to assume he's been The Mole since Revenge of the Sith, which shows him at the meeting between Obi-Wan, Yoda, and Bail Organa deciding what to do after Palpatine wrecked everything. That makes him extremely valuable, given that he's one of the very few people privy to some very important information. This is how the Empire was able to track the Tantive IV to Tatooine; not only was the pilot working for them, but he knew where he was supposed to go!
"That's funny. The damage doesn't look as bad from out here." You'll argue that's because Antilles was no fool, knew he couldn't win that fight, and allowed his ship to be boarded to distract the Imperials from Leia loading the plans on the droids and sending them to Tatooine's surface. No, it's because Antilles was hoping they'd catch Leia. Where was she going to go? Perhaps he didn't think Leia would use the droids — all that was her quick thinking. Vader killed Antilles after that either because he was a bit too enthusiastic in not blowing Antilles' cover, or because Antilles botched the operation and allowed Leia a chance.
Killing Antilles was a mistake; there was no better positioned spy in the Rebellion, and the Rebellion quickly put the Empire on the back foot soon after.
His plan was to do the same thing he did to Anakin — kill Leia's loved ones, make it seem like it was partly her fault, break her spirits, and fill her with anger. It was a lot harder with Leia than with Anakin. First, she knows much less about her own power; second, she grew up with a much stronger moral compass, especially from her adoptive father Bail Organa; and third, she's stronger-willed than the perpetually confused Anakin. But he had something he didn't when he tried to turn Anakin — a planet-killing machine. The trauma of blowing up Alderaan would be so great that it would overcome even Leia's optimism.
It didn't quite work like that, though. First, Palpatine didn't want to reveal his plans to anyone; he told Tarkin et al to blow up Alderaan, but he didn't tell them why. Tarkin was more concerned with finding the Rebel base and extracting that information from Leia and used Alderaan as a bargaining chip. Then he remembered that he was supposed to blow it up, and he did it anyway, after he promised he wouldn't if Leia gave the base away. (Maybe he didn't expect Leia to actually give away the Rebels? Except she didn't — she lied, too!) It did work to shock and disgust Leia, but not the way Palpatine expected; her anger was righteous rather than selfish, she resolved to work even harder for the Rebellion, and she never tapped into her Force power until Luke told her she could.
- He destroyed the sandcrawler himself and then tried to pin it on the Stormtroopers. His claim that "Only Imperial Stormtroopers are so precise" is belied by what we actually see from them.
- He personally killed Owen and Beru to convince Luke to go on the heroic journey with him. Luke spent a lot more time than the film implies looking for R2, which would give Obi-Wan time to torch the Larss homestead and then come back to rescue Luke from the Tusken Raiders. Alternatively, he previously rigged the homestead to explode (something he'd been planning for years), and Owen and Beru were killed in the explosion.
- The targeting computers were almost absolutely necessary to make the shot on the Death Star; Obi-Wan was hoping Luke would believe he didn't need the computer and thus convince him to miss. He underestimated Luke's belief in the Force; either he's a lot more powerful than Obi-Wan thought, or Luke managed to succeed out of Achievements in Ignorance (probably a combination of both).
- After Luke blows up the Death Star, Obi-Wan spends Empire trying to separate Luke from the Rebellion, where he would be a great asset, hoping to undermine the Rebellion. Instead, he convinces him to fly to the middle of nowhere in Dagobah and train with Yoda. He then tries to convince Luke that he's not ready to face Vader, perhaps because he doesn't want Luke to find out that Vader is his father. Speaking of which:
- He lied to Luke that "Vader betrayed and murdered your father." When Luke found out the truth and confronted Obi-Wan's ghost about it, Obi-Wan claimed what he said was Metaphorically True. But it doesn't jive with so specific a claim that Vader betrayed and murdered Anakin — that's a very odd way to characterise Anakin's fall to the Dark Side.
- And he set it all up in Revenge of the Sith by refusing to finish Anakin off and allowing him to survive and become Darth Vader.
Dying cures him; his Force ghost has perfect memory, and he can remember more clearly everything about Anakin and Vader. He just doesn't want to admit to Luke that his memory was that bad when he was alive (c'mon, it's embarrassing), so he tried to claim what he said was Metaphorically True.
This also explains a number of decisions that Obi-Wan made that don't make much sense, such as allowing Luke to use his father's surname and live with his father's known relatives on Tatooine. And it makes for an interesting parallel; if Vader hadn't sensed Obi-Wan's presence in a long time, maybe the other way around was true as well, and Obi-Wan never realised that Anakin had survived until their fateful fight on the Death Star. Perhaps not even until the middle of the fight, hence why he addressed Vader as "Darth" earlier.
The big problem with this theory is why Obi-Wan would refer to Anakin as a former student of his. But as with any WMG, this can be explained in a needlessly convoluted way: Obi-Wan saw Darth Vader take Anakin's place as Palpatine's apprentice and basically assumed that Palpatine had procured yet another Sith. After all, he's personally fought enough of them (Darth Maul, Count Dooku, Anakin). But this time, Obi-Wan is horrified to see this "new" apprentice using the Force in a way very reminiscent of how he taught Anakin. He doesn't make the connection that Vader does this because he is Anakin, but he does realise that his techniques are now being taught in service of The Dark Side, and he blames himself. He's not sure where Vader picked up those techniques, but they're his, and he may as well have taught them to Vader. That's why he considers Vader his "pupil", and that he learned the techniques "before he turned to evil" — they weren't evil when Obi-Wan was teaching them. Indeed, Obi-Wan steadfastly continues to teach Luke the Force in the same way.
Indeed, the original Obi-Wan we see in the prequels was not a clone; both of them were cloned from him. He saw the process up-close in Attack of the Clones and over time got curious enough to try it on himself. Interestingly, both "Ben Kenobi" and Uncle Owen, as seen in A New Hope, seem to have aged more rapidly than they should have given the time interval between then and when we last see them in Revenge of the Sith, suggesting the rapid aging didn't go off seamlessly. Obi-Wan set up the clones to watch Luke and Leia at the same time; the real Obi-Wan went incognito to train in the Force, much like Yoda did on Dagobah. O-1 was assigned to Luke, and OB-1 was assigned to Leia. Both were to have active roles in the kids' lives, but Bail Organa was promised that he'd get to raise Leia, so OB-1 was eventually booted off Alderaan and doubled up with O-1 on Tatooine. The mixup led to the idea that the real Obi-Wan was on Tatooine and not the clone, so R2 accidentally delivered the message to the wrong person. The real Obi-Wan (who may well have been long dead by then, so this would be his Force ghost) figures out what's up, manipulates the clone into training Luke in the Force, and then has the clone body self-destruct in the fight with Vader. Everything after that is the real Obi-Wan's force ghost talking to Luke, while taking on the appearance of his clone so as not to confuse him.
The idea that Obi-Wan and Owen were clones is an old WMG, incidentally. It doesn't work well in the context of all the films, but in the late 1970s, right after Star Wars came out, this was actually a popular fan theory.
There are two obvious reasons for him to do so: first, he can "become more powerful than [Vader] can possibly imagine," and second, it distracts Vader while Luke and friends can make it to the Falcon and escape — notice that Obi-Wan and Luke make eye contact before Obi-Wan raises his lightsaber and invites Vader to hit him. But there's another more subtle factor at play — he needed Luke and Leia to get away from Vader, before Vader senses their power with the Force and realises exactly who they are. That's a big reason why Obi-Wan made eye contact; he had to convey to Luke that he was making a Heroic Sacrifice. Luke didn't understand exactly why, but he understood enough. There's also the likelihood that Obi-Wan had grown so disgusted with Vader's ego and obsession with showing his power that he wanted to deny Vader the satisfaction of a good fight.
Obi-Wan's plan relies on a deliciously Dark Side-like manoeuvre: get Luke to hate Vader and the Empire. He tips off the Stormtroopers who shoot the sandcrawler and makes it a point to tell Luke, when he sees the slaughtered Jawas, that the Empire was responsible. He tells Luke in no uncertain terms that Vader killed his father (not that he is his father), hoping to give Luke the idea to kill Vader in revenge. He was responsible for Owen and Beru's death; another WMG on this page says he did it himself, and it's unlikely that the Imperials would have actually murdered Owen and Beru and burned the ranch rather than just arrested them and waited for Luke to come home. And he set up his fight with Vader to ensure that Luke saw Vader land the killing blow, giving him another reason to hate Vader. It would have worked, had Vader not revealed to Luke who he really was, something Obi-Wan didn't anticipate.
But it wasn't that long ago that Jedi were running around more openly. It's one of the biggest pieces of Fridge Logic in the entire saga; how, in the span of maybe twenty-odd years, did the entire Galaxy go from acknowledging the Jedi as an actual political entity, with their own council and everything, to believing they didn't exist? Sure, maybe nobody believed the stuff about the magic powers, thinking it was all a "hokey religion". But they were well-known. And specifically, Obi-Wan Kenobi and Anakin Skywalker were known as war heroes (said explicitly in the novelisation of Revenge of the Sith), so it's not out of the question that Han would have heard of them. And when all of a sudden he starts smuggling two guys with the same surnames, who are sufficiently connected to pay him 17,000 credits if they get to Alderaan, he starts freaking out about what exactly is going on. He doesn't want to get involved in something overtly political that could get him in trouble. He says bluntly that he doesn't believe in the Force and that's not why he's helping them (after all, he "ain't in this for [their] revolution"). Maybe he was a little too forceful, but whatever.
Also, Han's shipmate Chewbacca was around for the old Republic stuff and met Yoda personally. He should have been freaking out equally hard, for the same reason. Unfortunately, we can't always figure out what he's saying.
He knew the droids had the plans but let them escape from the Tantive IV to give himself Plausible Deniability. Why steal the plans from the Empire when he can deflect suspicion by stealing them from someone else who stole them from the Empire? He would hunt down the original thief under Imperial authority, but instead of handing the plans back to the Empire, he would keep them for himself and pretend they had been destroyed. He didn't expect that his old friend/nemesis Obi-Wan Kenobi was down on Tatooine and would know how to keep the plans from him.
Owen and Beru are skilled combatants; that's why the Jedi were so confident leaving Luke with them. But they didn't like fighting and didn't want Luke to learn what they knew. However, once the Empire came for them, they realised the significance of the droids they bought and why Obi-Wan was so interested in Luke all of a sudden. They pretended to be dead so that it would be easy for Luke to go with Obi-Wan, then they followed him to the Death Star in Stormtrooper guise. Now, they start missing — but they're not actually trying to hit Luke. Other Stormtroopers are easily swayed to leave him alone. Owen and Beru prove to be adept at obstructing the competent Stormtroopers and never letting them get to Luke, doing things like closing the blast doors.
At the end of the movie, Owen becomes one of Vader's wingmen. He sees an opportunity to destroy not just the Galaxy's most terrifying mass murder weapon, but also Vader, his own step-brother, who so stained the family name. He would do this even if it cost him his life. At the end of the film, Owen "loses control" of his TIE fighter, clips Vader's wing, and sends him flying out into deep space. He didn't kill Vader, and he died in the Death Star's explosion, but he did give Luke the chance to blow it up.
By The Empire Strikes Back, the Stormtroopers are suddenly more competent (look at their performance in the Hoth battle). That's because now the traitors are no longer in their ranks causing trouble.
- They were inferior versions of the Clone Troopers we saw in the Prequel Trilogy. They weren't made from the same process, and possibly not from the same template. The Empire didn't want to spend the money on well-trained and well-developed clones like the Republic did.
- They were made from the same template, but Jango Fett had twitchy aim. It was his one weakness.
- Their equipment sucks. They can't aim in those helmets, especially in the dark. Heck, even when Luke put on the helmet for his disguise, his first comment was, "I can't see a thing in this helmet!"note And if the Empire didn't want to splurge on the cloning process or the equipment, we can assume their blasters have crappy aim, too.
- They have trouble shooting at human targets. They're fine with Faceless Goons, or aliens like Jawas, or big machines like sandcrawlers — that allows them to shoot with precision. But they're reluctant to shoot humans. It's a known aspect of human psychology. Combine it with the idea that they're poorly trained or recently conscripted, and you've got a really Reluctant Warrior.
- They've been subject to mind manipulation. The Republic never did this with its clones because it had at least some honour in fighting a war. Palpatine has no such honour and routinely overrides the clones' minds to prevent them from asking tricky questions. By the time of A New Hope, they've been worn down so much mentally that they can't aim anymore.
Or maybe they weren't so terrible after all, because:
- The characters they miss all have Plot Armor. We don't see them shoot others too often, but when they do, they have a great hit rate.
- Their blasters are Slow Lasers, meaning you see many more shots than you would from a conventional firearm. The same hit rate looks a lot worse coming from a Stormtrooper than from someone using a gun we're more familiar with.
- Half the time, they're trying to let the heroes escape. Certainly this was the case when Luke and friends escape the Death Star; the Stormtroopers are betting (correctly, as it turns out) that they'll lead them to the Rebel base. Leia seems certain that they let them escape.
- They know not to aim at lightsaber users, who are damn good at Parrying Bullets. They have orders to shoot, so they can't just hold their fire, but their aim is conveniently crap to prevent the Jedi from deflecting the lasers back at them. Maybe early in the film they wouldn't have expected to encounter a lightsaber user (it had been so long since anyone had used one), but they might remember what it was like in the old days when Jedi used them in battle routinely.
For instance, who would design the Death Star with such a fatal flaw? Sure, exhaust ports are necessary, and you can't design them with a cover because that would defeat the entire purpose of an exhaust port. But to route a port directly from the surface to the core of the station, such that a single well-placed torpedo could blow the whole thing up? That's inexcusable, no matter how impossible that shot might be. A Rebel sympathiser might well believe in the power of the Force and know a bit more about the capabilities of the pilot who would make that shot. Or maybe they were just fed up with Imperial arrogance and installed a deliberate design flaw in the hopes of embarrassing the Imperial leadership for not catching it, not expecting that any Rebels would actually make that shot.
Or the guy who says, "Hold your fire, there are no life forms on board." The stupidity of that decision has been lampshaded for decades, in sources from Family Guy Presents: Laugh It Up, Fuzzball to Darths & Droids. Was it really ingrained belief in inferiority of droids? Was it really extreme cockiness? Was it really extreme cost-cutting? It would be more logical to think that this particular guy was in on it.
Or the TIE fighter pilot who clips Vader's wing and sends him flying off into deep space, out of control. He did that on purpose; he could see that his comrades were being treated as if they were totally expendable. The pilot, sensing his own impending demise, tried to make it count and rammed Vader into the Death Star. Except he missed, and Vader slipped out into space, allowing him to survive the Death Star's explosion.
- Confirmed for the first part in Rogue One - the Death Star was purposely designed that way.
Come on — don't act so surprised! You do know Batman Can Breathe in Space.
- Wookiees don't believe in medals and honours. He was offered a medal but refused because it was against his religion. Perhaps even Han (or someone else who knew Wookiees) told this to Leia and she knew not to offer it to begin with. Or, if you want to get funny, Han told this to Leia, but Leia didn't believe him, thinking he was trying a mean prank on his friend, only to offer it to Chewie and then get roared at and realise she was the one getting pranked all along.
- Chewie refused it for symbolic reasons. He believed that blowing up the Death Star was winning the battle but not the war, and he wanted to make sure the Rebels won the war. (Indeed, this is exactly his reasoning in Darths & Droids.)
- The medals were given for destroying the Death Star. Neither Han nor Chewie were supposed to get one because they didn't actually hit the Death Star, but Han was a Glory Hound who insisted on getting one for his role in giving Luke the clear shot. Chewie was more chill about it and just went to the ceremony.
- Leia was a little speciesist and didn't think Chewie deserved a medal. She did call him a "walking carpet" and didn't seem to like being around him. "I'd just as soon kiss a Wookiee" from the next film was meant to be particularly nasty, but Han didn't catch on.
- Chewie and Han are Heterosexual Life-Partners, and the medal Han received was actually meant for both of them.
- Chewie already had a medal, having gotten it on Kashyyyk. It was just hidden under his thick fur.
- Chewie was too tall for Leia to reach. He didn't want to bend down because it would have been offensive to him, and they didn't want to put Leia on a Scully Box because it would have looked kind of stupid. Interestingly, this is not only mentioned in the EU, but it's also the reason out of universe; Peter Mayhew was that much taller than Carrie Fisher. (Mayhew joked that Chewie got compensation by getting the last line of the film.)
Chewie's lack of medal, and the unintentional insensitivity it showed from our heroes, is a problem that's bothered people for so long that they belatedly gave Chewie his medal in The Rise of Skywalker, perhaps just to get everyone to shut up about it. No can do — this is WMG!
It's part of a greater arbitrary resolution to the problem of why, if Vader was the Chosen One who was prophesied to bring balance to the Force and was instrumental to Palpatine's rise to power, he's basically a high-ranking grunt in A New Hope. It also dovetails interestingly with a scene in Star Wars Rebels, in which Tarkin executes a couple of underlings for their failure, whereas in this film he stops Vader from doing the same thing to Admiral Motti — rather than trying to keep useful officers on board, Tarkin may simply be reminding Vader that on his battle station, he's the one arbitrarily deciding who lives or dies.
- They only know two songs.
- They only know two songs in the genre the clientele actually tolerates. If they play their usual stuff, they'll be killed.
- It's part of a single really long song, which explains their stylistic similarity. It could be a suite or a concerto.
But what if it wasn't the writers who made the mistake, but Han himself? Indeed, early drafts of A New Hope indicate that Han is deliberately making up his accomplishments and that Obi-Wan is not fooled by his "obvious attempt at misinformation." Indeed, if you look at Alec Guinness in the finished film, his expression shows just that. Han was making up the whole Kessel Run thing.
There are two reasons why Han would make it up:
- The first is that he's feeding Obi-Wan and Luke information he knows is nonsensical to see how much they knew about space travel. Presumably, Han would be more interested in transporting someone with no frame of reference for space travel; it feeds his ego, and he can rip them off by preying on their lack of knowledge. Obi-Wan made a face and made Han think twice about taking them; then Obi-Wan offered 17,000 credits, and Han figured he could do the job they wanted for real. (Obi-Wan's expression may well have saved the entire Galaxy; if he hadn't done that, Han would have taken the two of them on a joyride and they'd never have made it to the Death Star.)
- The second is that Han really doesn't know what he's talking about. He's got a fast ship, but he blundered into it; even canonically, he won it from Lando in a card game. Lando was the one who made it as cool and fast as it is. Chewie probably knows a lot more about how it works than Han does. Han's a little insecure about his lack of knowledge and tries to make up for it, but he can't do it realistically. Specifically, he wants the ship to be famous; as a smuggler, he can't really do anything attention-grabbing in it (aside from outrun Imperial starships), but he also doesn't know what realistically he could do with it that would make it famous.
Indeed, when we see the destruction of the Death Star II over Endor, we see fragments of it break away. But we don't see that in the first one — just a bunch of gases, a single fantastic flash centred exactly on the core. The first Death Star didn't blow up — it explosively activated its hyperdrive! The Rebel engineers who were analysing the Death Star plans figured that a torpedo shot into the exhaust port would cause a devastating chain reaction, perhaps by destroying some important power relay or control mechanism. They theorised that this would blow up the station, but they turned out to be wrong.
However, the inadvertent and violent hyperdrive activation slid the Death Star all the way out of the Galaxy. It popped out far, far away, out in the middle of nowhere, and the crew on board either didn't survive the journey or starved to death trying to survive. The Death Star, after a long time, became one of the many moons of a local gas giant. And that gas giant is our planet Saturn, and in Real Life it's the moon Mimas. That crater that looks like the Death Star's superlaser is the Death Star's superlaser! (You'll be amused to know they named it "Herschel".)
Indeed, in Rogue One we see the Rebels muster a battle fleet powerful enough to destroy two Imperial Star Destroyers and an orbiting space station, and launch a successful commando raid of the planet-side intallation. That might have been enough to scare Tarkin and the other Imperials into thinking that the Rebellion has enough firepower to win a battle with them if they get caught off-guard. That implies that there's a lot more to the Rebellion than we saw on Yavin. The only way that the Yavin base is all that's left of the Rebellion is if the Rebels really did dedicate most of their forces to the Scarif raid that got them the Death Star plans.
- Boba Fett was on Tatooine at the time.
- It was not in the interests of the Stormtroopers to actually kill Owen and Beru; they could have just arrested them and waited for Luke to return to them with the droids.
- Even if circumstances dictated that the Stormtroopers did need to kill them, they would not have been needlessly cruel and petty as to cook the flesh off their bones and torch their homestead.
- Stormtroopers blasters should not be powerful enough to do leave a frigging skeleton behind. But Boba Fett does have weapons that can do that. It's quite telling that in Empire, Vader sees fit to specifically tell Fett, "No disintegrations!" — implying that it was a thing he did.
But Grand Moff Tarkin was too emotional about Leia's defiance, and drunk with the power of the Death Star, he acted unilaterally and blew up Alderaan. Palpatine was pissed, and Tarkin just hung around on the Death Star for a bit trying to avoid his boss giving him a chewing out. That chewing out would probably have been fatal, but the destruction of the Death Star made the point moot.