[simne]

> Dark matter interacts only gravitationally and is currently the leading explanation for things like galaxy rotation curves

Not exact. For so weak technologically civilizations such our Terrestrial, now could not detect many distant objects which does not emit EM spectrum.

For example, only small fraction of known planets outside our Solar system, seen on telescopes directly, most others detected by indirect means - measuring difference of speed of star (by Doppler shift), or measuring changes of brightness of star, when big planet eclipse star (most cases partially).

In many cases, planets orbits are not so fortunate to us to detect them, and these planets for us are dark matter also.

To be exact, for us "normal" matter are only classic stars and some other objects like Black holes when they "eat" something.

Astronomers already made calculations, based on assumption, that Solar system is more or less typical (we know approx weights of matter of Sun, Planets, Asteroids, Star dust, etc), and seen, that all we know could been about half of dark matter, but other half we could not explain, and this is huge number.

[hollerith]

>planets orbits are not so fortunate to us to detect them, and these planets for us are dark matter also.

"Dark matter" has a technical meaning in astronomy, and this is not it.

[simne]

You confused PHYSICS definition with ASTRONOMY definition, they are different.

For ASTRONOMY, dark matter is just what they could not see, but have gravitation features. And as I said, for astronomy, ~50% of dark matter is nothing special, but for example, only extreme models could suggest tens of thousands Black holes (to fill 50% of emptiness), because of this, they conclude, that exists something other matter which we don't know.

For PHYSICS, technical meaning of dark matter is special type of matter.

[hollerith]

But the person you replied to was using the physics definition, and you reply as if he used the astronomical definition.

[simne]

We have confusing and extremely sophisticated context. It involving wide spectrum of less complex contexts. Physics and astronomy, depend on from what direction we look on it.

Good that we found understanding on this.