What observations suggest the mass of the Galaxy goes much ...

[schs14]

What observations suggest the mass of the Galaxy goes much farther out than its visible disc?
 
  A) the rotation curve of the outermost portions of the disc
  B) 21-cm maps of the spiral arms
  C) infrared observations of distant brown dwarfs
  D) the orbits of the open clusters in the disc
  E) X-ray images of other galaxies' discs from Chandra

Question 2

Why was the discovery of a substantial magnetic field around Mercury a surprise? How was it detected?
 
  What will be an ideal response?

[Danny Ewald]

Answer to Question 1

A

Answer to Question 2

In its close passes by Mercury, Mariner 10 found a field that is much stronger than Mercury's very slow rotation would have led us to expect with the dynamo theory.

[schs14]

TY

[Danny Ewald]

You're welcome