xkcd.WTF!?

Explanation ➲

This is one of Randall's My Hobby comics. The author makes semantically incorrect statements to frustrate pedantic people who know the correct word, and confuse people who don't know the precise word so they can go on using the wrong word; see also 1429: Data. Since Randall is normally personified by Cueball, it makes most sense to call the one with the hobby Cueball in the explanation below.

Cueball's friend (who also looks like Cueball) walks up to Cueball and tells him that he has found a piece of a "meteor". Cueball corrects him by telling him that what he found is called magma, and that the phrase "a piece of a meteor" would be correct if the object was in the air, once it hits the ground it is called magma. In doing so he attempts to confuse or annoy his friend. In truth, meteorite is the expression for a piece of a meteoroid that has landed; meteor is the term for the streak of light caused by the meteoroid while it falls through the atmosphere. Thus the first statement by him is a (partly) true correction, but the second one is wrong.

The word "pedantic" means being overly concerned with being precise. It is usually a pejorative term used to refer to someone who is overly fussy and corrects someone's word choice even when the more ambiguous or slightly incorrect term they used was fine for informal communication. One would tend to believe a pedant, as they would usually know what they are pedantic about. So when Cueball is making wrong statements that seem pedantic, he may make people believe him. A volcano that would be the bane of such a pedantic person was depicted in the last panel of 1714: Volcano Types, as a direct reference to this comic.

It is also worth mentioning that, technically, water is a form of lava. Ice is a mineral, since it has a definite crystalline structure and has a definite chemical structure (H₂O). And molten mineral is lava. Therefore, our bodies are made up of up to 60% lava. See Vsauce’s video for more info.

The title text expands on the joke, as if the conversation had continued with a confused friend responding that he thought magma was underground. Cueball attempts to confuse him further by talking about lava which indeed is the expression for magma that has reached the surface. But it's ridiculous to suggest that all other things are called lava when underground. In the sentence he also continues to imply that magma could also be found above ground. Mixing pedantic terms like this was later used in the title text of 1967: Violin Plots. The two sentences thus follow the same pattern with one true but pedantic part to begin with, and then a false statement to confuse the victim.

Meteor & Magma

Here is a list of the terminology that is being muddled:

• The descent of a small solid body from space:
  • A meteoroid is a small solid body traveling through space outside the atmosphere.
  • A meteor is a streak of light produced by a meteoroid as it burns up in the atmosphere.
  • A meteorite is a piece of a meteoroid remaining after it strikes the ground.
• Molten rock:
  • Magma flows underground.
  • Lava has been extruded to a planet's surface, as through volcanic eruption.

A nice English mnemonic helps: In the void, meteoroid. On the site, meteorite. Neither/Nor: meteor.