Question turned out to be off-topic. "Migrated" to Worldbuilding.

I'm referring to two events that I recall immediately (the destruction of the Borg planet in the Scorpion episode of Star Trek: Voyager; and the destruction of Alderaan in Star Wars), but there are dozens of similar examples, if not hundreds, in the entire SF&F canon.

What events are actually meant to happen when a high-energy laser beam hits a planet’s surface that lead to the destruction of the entire planet?

Some of my (maybe very lunatic) possibilities and theories (to verify):

  1. The laser beam penetrates the surface, reaches the core, raises its temperature to boiling or even melting point, and pressure in the surrounding area causes the entire planet to explode.

  2. The laser beam hits only the surface or not-so-deep areas beneath it, but due to surface’s stability being destroyed, this is enough to cause the explosion of entire planet.

  3. The laser beam doesn't even hit the surfaces, but causes changes to the atmosphere starting some kind of destructive process.

Is there any, verifiable by our present knowledge (geology, physics, chemistry), common means of explanation that can be adapted to each or most of examples of such events? Or must each of these examples and situations be treated separately (and each book, story or scenario author does it by its own -- i.e. brings its own theory or explanation)?

EDIT, to clarify: I really believe, this is a pure science-fiction question. I'm referring to exactly these two examples I given (destruction of Borg planet in Star Trek and destruction of Alderaan in Star Wars). And this question is tagged with proper tags. This question somehow turned into be too wide or even general, but the key facts remains. Few days ago I watched VOY: Scorpion again and become really interested, how a fairly small armada of nine (?) bio-ships, can destroy entire planet with a just single blast of laser beam? Star Wars example is an addition, but in the very same mood -- in my humble opinion, even that big Death Star shouldn't have (by a very wide and general means) a firepower enough to blast entire planet hell (since Death Star itself is smaller than an average moon, if I'm not mistaken, and for sure much smaller than Alderaan).

closed as off-topic by BESW, James Sheridan, Valorum, user8719, The Fallen Mar 24 '14 at 10:23

This question appears to be off-topic. The users who voted to close gave this specific reason:

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  • 1
    "high-energy laser beam" It would seem that a lot of the plausibility of a laser destroying a planet would depend on the exact (or at least order of magnitude) figure of high-energy is pinned down, and released in what amount of time.. Of the 3 scenarios outlined, I find the first most plausible. The 2nd might result in a shock wave that knocks a large chunk off the opposite side of the planet, but not a 'complete annihilation' as generally depicted. And the 3rd might blow the atmosphere away and melt, boil or ionize the first ground it reached. – Andrew Thompson Mar 24 '14 at 7:31
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    Could be a question for what-if.xkcd.com :) – Johann Blais Mar 24 '14 at 8:52
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    @JohannBlais: more or less already done towards the end of what-if.xkcd.com/20 - OK, it doesn't involve a laster, but I suspect that at that energy level, it makes little difference. – Michael Borgwardt Mar 24 '14 at 9:15
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    @trejder: “real-world science hasn't ever seen an entire planet destroyed as an effect of hitting it with a laser, right?” — I like to think I’d remember that :) – Paul D. Waite Mar 24 '14 at 10:03
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    @trejder: Regarding whether this is a sci-fi question, this site is for questions about science fiction (i.e existing works of fiction). If you’re asking what explanations authors have given for how planets explode from laser fire, I think it’s fine (although it’s a bit of a list question). If you’re asking for how this could happen in the real world, that’s a question about real-world science, albeit a speculative one. It’s a fine line, admittedly. – Paul D. Waite Mar 24 '14 at 10:05