Smallest galaxies packing the most

[Jason]

The Smallest Galaxies In The Universe Have The Most Dark Matter

If you want to find dark matter, there’s one simple rule: you follow the mass. Indeed, if you look at the largest structures in the Universe — big galaxies, groups of galaxies, or even the most massive clusters — they all show the same thing: their internal motions are all too fast to be explained by the gravitation of the matter we know is there.

http://www.forbes.com/sites/startswitha ... rk-matter/

[JimC]

...their internal motions are all too fast to be explained by the gravitation of the matter we know is there....

Poorly worded and imprecise, IMO. The stellar motions cannot be said to be "explained" by gravitation...

It would be better to say that the rotational motion of galaxies, and the average random velocities of their constituent stars, are both too high for them to remain as a coherent galaxy without the constraining effect of a considerable amount of extra gravitational force, beyond that supplied by observable stars and dust, and that we presume that this comes from some form of additional dark matter.

[mistermack]

...their internal motions are all too fast to be explained by the gravitation of the matter we know is there....

Poorly worded and imprecise, IMO. The stellar motions cannot be said to be "explained" by gravitation...

It would be better to say that the rotational motion of galaxies, and the average random velocities of their constituent stars, are both too high for them to remain as a coherent galaxy without the constraining effect of a considerable amount of extra gravitational force, beyond that supplied by observable stars and dust, and that we presume that this comes from some form of additional dark matter......