Messier 42, better known as the Orion Nebula, is located roughly 1,344 light-years away in our spiral arm of the Milky Way. The nebula itself is quite huge, at about 40 light-years in diameter. For a bit of perspective, Earth is about 8 light-minutes away from the Sun. Though the nebula can be seen in the constellation Orion with the naked eye, it just looks like a little point of light, just like a star. If it were only 4 light-years away, the nebula is massive enough that it would completely dominate our view of the night sky. 

Check out this clip from The Universe that shows how it would look:

It’s worth pointing out that the image used has been color-processed and has an exposure time of nearly an hour per filter, so our eyes wouldn’t be able to see it look quite as spectacular as this. But, it’d still be a hell of a view.

[Hat tip: reddit]