[dangus]

>> Neptune doesn’t qualify since it’s not dark and we know what it is. <<

Read the article. Dark means “unknown.” We know what it is NOW, but it WAS dark matter. When we discover what more of dark matter is, it will no longer be dark, also.

[Telepathic Intruder]

Point taken. However, dark matter was never a term until Fritz discovered that there was unaccounted matter in the universe.

The discovery of Neptune was based on the assumption that there was a planet there, which is correct. It was never assumed that it was something entirely unknown at the time. Today, no one still has the answer of what dark matter is. Only hypotheses.