Astronomy haiku: dark matter

Astronomy 210 Haiku review, fall semester 2011
Cuesta College, San Luis Obispo, CA

Students find their assigned groups of three to four students, and work cooperatively on an worksheet to review for a midterm.

Identify the relevant astronomy concept/answer for this haiku. Briefly explain your choice. Partial credit possible.

Surrounding halo,
invisible gravity.
Holds Milky Way tight.
http://twitter.com/#!/Patrick_M_Len/status/72024267604234240

Concept: __________
Explanation: __________

Section 70160

"Dark matter--Evidence that extra mass lies in extended halo sometimes called dark halo. Not luminous matter detected by its gravitational force."

"Dark matter--No one has seen dark matter because it doesn't give off light, but it creates gravity, so we know it exists."

"Dark matter--Proves Kepler's third law wrong because stars farther out do not move slower because there is no center of gravity."

"Dark matter--Dark matter is gravity that holds the Milky Way together and is unable to be seen."

"Dark matter--The Milky Way doesn't follow Kepler's third law."

"Dark matter--Dark matter is invisible and it holds everything inside the Milky Way."

"Dark matter--Dark matter holds the Milky Way together."

Section 70158

"Dark matter--That's what holds the Milky Way together."

"Monolithic collapse--flattens out over time with halo making disk left."

"Dark matter--Dark matter is the unseen gravity force which fills the universe around galaxies, surrounding the Milky Way."

"Black hole! You know black holes are present when there is a gravity alteration like an entire galaxy clumped together."

"Dark matter--Dark matter is the stuff that surrounds the Milky Way and keeps everything tight."

"Black hole--Black holes are at the center of spiral galaxies and have infinite gravity due to their immense density."

"Dark matter--Dark matter surrounds galaxies, holding them together as they rotate with lots of mass."

"Antimatter/dark matter--is found all around the Milky Way and is unexplained but we know it's there."

Dark matter--Dark matter is invisible but still creates a gravitational pull."