Title text:
After a lot of analysis, I've determined that they're actually big red dots; they're just very far away.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3212/
There's a mineral called jasper that is often reddish brown, but it can also appear in a lot of other colours. So unlike malachite, ruby, or emerald, it's not a great name for a colour.