Quote Remarkable_Rhinos="Remarkable_Rhinos"Ah yes, well spotted. I'm particularly irked by Earth/earth. Likewise with World/world. I'm sure that world is grammatically correct these days, but it will always be World to me.'"
It entirely depends on how you're using it. If you are referring to the Earth, as in this planet, it is a name and needs a capital. It is entirely possible to use "earth" in other contexts, including as soil or ground, without capitalising.
Similarly, when referring to the World it should have a capital, whereas if you are referring generically to a world, as one of many, then it doesn't need a capital. At least that's how I've always understood it.
Similarly in my work I may refer to something being done by a department, university or trust. However, if I mean to identify a specific department, university or trust, than it is the Department, the University or the Trust.
I could be wrong of course, but nobody has ever complained.