What about two small black holes whizzing around the center of the planet, inside it? Orbiting around each other and the planets core in decaying orbits until they collide?
Initially they’d be quite close to the surface, causing earthquakes, strange tides etc due to tidal forces. Letting someone, we’ll call him Jor-El, put the pieces together. But as the orbits shorten, they’ll be further and further into the planet, causing more long term damage but becoming far less immediately noticeable, and making Jor-El look like an end-of-the-world lunatic. And then they go into a decaying final spin around their common center, making it all irrelevant.
If out Jor-El knew what was going on, he’d probably be able to calculate the orbits quite precisely and know exactly how much time he had left.
This is actually a really cool idea – it might also explain a lot of Superman’s powers on earth… a white dwarf star would have incredibly strong gravity, so any life that evolved/adapted to live on the surface would have to be extremely physically strong and sturdy.
How soon before “Dr. Strangelove” reveals he’s actually Randall Munroe, and the post in question was prepared for an xkcd “what if” column since aborted?
Eh, the topic’s been covered plenty of times before, and the binding energy of a planet is easy to look up. Munroe usually covers things a lot more bizarre than that.
Red giant stars don’t do that. They do expand and engulf and vaporize planets, but that doesn’t leave the planet habitable until it gets torn apart. In fact, main sequence stars get brighter as they burn their hydrogen, which gradually heats up the planets over a timescale of billions of years. The Earth will become uninhabitable long before the Sun becomes a red giant because of this.
If you want to use gravity to tear a planet apart, you have to get it really close to a more massive planet or star. Look up the Roche limit for details, but a quick and dirty estimate is about 2.5 times the radius of the larger body, assuming similar composition for both bodies (ie, this won’t work for a red giant and a planet).
Either that, or you need a very energetic collision. This isn’t likely to happen in a solar system that has been around for long enough for advanced life to evolve. Rogue bodies tend to collide with other bodies or be ejected from the system long before that. You could have a smaller object going at very high speed, but that’s going to mean it’s not gravitationally bound to the star. Those are rare- interstellar distances are such that a gravitationally unbound object isn’t likely to happen into a solar system, and they don’t stick around if they do.
I’d say a collision or getting within the Roche limit of a bigger planet are probably your best bet, although those are both very unlikely to happen in an actual solar system. You wouldn’t be able to have them happening and only one scientist knowing that was what was going on, though. You’d have to have something that was severely disrupting the orbit of at least Krypton and possibly other planets in the system. That’s the kind of thing that tends to be obvious, especially for a species that has space travel.
You could have a collision with a rogue object, if Jor-El had developed a new sort of astronomical instrument that could detect it coming when nobody else could (the most dangerous sorts of objects would also be hard to detect directly). Other scientists might be able to use Jor-El’s instrument to detect the incoming object, but dismiss it as noise, while Jor-El, who knows the true noise floor of his instrument, refuses to dismiss it. Note that we’re dealing with human(ish) scientists, here, not perfectly logical computers: In addition to all of the usual scientific difficulties, you’ll also have some degree of people burying their heads in the sand because they’re afraid to acknowledge the implications. You might even have some scientists who privately agree with Jor-El, but who have decided that there’s nothing that can be done to avert it, and that it’s therefore better to avoid panicking the public.
This idea I like. One estimate I’ve seen is that 20% of the mass-energy of the two colliding black holes would be converted into energy; so we are talking about the collision of 2 black holes, each 1.24 x 10e12 x (20/100) tonnes in mass; 6.2 trillion tonnes each. (One black hole represents the mass of the antimatter, the other the mass of the matter required to destroy the Earth; multiply by five because only 20% of the mass energy is liberated in a black hole collision.)
A black hole massing 6.2 trillion tonnes would be 0.009206079 nanometres across, and could pass though the Earth as if it were air.
A bit unlikely- most astronomical instruments aren’t developed by lone wolf inventors, but by a group of scientists. Put this on top of the unlikelihood of a rogue object capable of destroying a planet…
I do think there might be some attempt at a cover-up if a catastrophe that we couldn’t do anything about was about to happen. This isn’t likely to be a planet-destroying event, but might be something like a large comet (dinosaur killer or larger) headed toward us. This could theoretically have happened with Comet Hale-Bopp, which has a nucleus 40-80 km in size (usual estimate I’ve seen for the dinosaur killer is 10 km) and was discovered two years before it would have hit. I’m not sure how well the cover-up would work, though. Hale-Bopp couldn’t have destroyed the Earth, but it could have done some serious damage to the biosphere. If it had been on a collision course with Earth, there is nothing we could have done about it.
Well, except for the fact that the smallest black hole we’ve found so far is 3.8 times the mass of the Sun. It’s about 24 km in diameter, so it would fit inside a planet, but it’s not going to whiz around inside the planet- you wouldn’t have a 3.8 solar mass object in a tight orbit around the center of a planet. You’d need two black holes smaller than the mass of the planet. We haven’t found even one black hole this size, let alone two that collided with the same planet. If there are black holes this size, then you have to have a planet capture two of them in very small orbits. Unlikely. I suppose if the Kryptonians had some way of manufacturing small black holes it could happen.
Difficulty there: While black hole collisions can release insane amounts of energy, it’s almost all in the form of gravitational waves, which will mostly just pass right through the planet.
You would only need to release enough energy to blow the land surface apart, and only a meter or so deep, and you don’t even need to prevent the bits from falling back down, in order to have an effective Krypton-shattering Kaboom. A large asteroid passing by might be enough.
But then how did kryptonite get spewed across the universe?
Come to think of it, the existence of kryptonite on Earth means the event that shattered Krypton had to be even more energetic than what would be required to shatter a planet. The explosion not only shattered a planet, it propelled at least some of the pieces outside of that planet’s home solar system. For a chunk of the Earth to escape Earth’s gravity, you’d need to get it to an escape velocity of about 11.2 km/sec. For that same chunk to escape the solar system, you’d need to get it to 42.1 km/sec. The exact numbers are going to vary depending on the mass of Krypton, its diameter, its distance from its star, and the mass of the star.
In the real world, yes. But this kind of thing happens all the time in comic book universes.
Something like this must have happened, since otherwise there wouldn’t have been enough time for the rocks to travel all the way from the Kryptonian system within the lifetime of a single Kryptonian.
If you allow wormholes, I suppose you add some interesting ways to blow up a planet. Connect the core of a planet to the core of a star and you’d have the energy input needed to overcome all that gravity. Even if the planet eventually coalesced, it would still be destroyed for all intents and purposes that matter to life forms.