Who caused The Dark Sun

Even this soon after it happened, theories abound as to just what's going on with the sun, but there's one thing all good scientists* have agreed on: it isn't natural.** It may not be supernatural, but it's certainly extranatural.***
This event wasn't caused by something, it was caused by someone. The question isn't "What?" it's "Who?" "Why?" and "How?"

Who?

• A secret superadvanced organisation
• Aliens
• People with access to magic
• Terrorists with access to magic
• Vampires with access to magic

Why?

• Accidental
• A simple way of modifying the Earth's biosphere
• Attempting to conserve Sol's energy
• To threaten the world powers
• To avoid severe sunburn problems

How?

• A side-effect of an FTL probe
• A side-effect of investigating Sols structure
• Some form of shield around the sun
• Some sort of advanced shield around Earth
• Increased internal solar reflection
• Magic

I'll try and explore these possibilities tomorrow, or soon at least. Well, it'll be tomorrow if the sun rises, and if not I suppose it'll still be today only less so.

*No, I haven't asked all good scientists, hell I haven't asked any: I'm still right
**Provided, of course, you use a definition of natural which excludes sentient beings.
***Interesting that "extra" means more, and "super" means better version of, but neither meaning applies here.