A Kuiper Belt object was discovered that may be larger than Pluto.
Indicate whether the statement is true or false
Question 2
How are rotation curves of spiral galaxies determined for distances beyond where starlight can be detected?
A) by measuring the broadening of the galaxy's absorption lines
B) by extrapolation of the measured rotation curve
C) by observations of spectral lines emitted by dark matter
D) by watching the galaxies rotate over a period of decades
E) by observations of the 21 cm line of atomic hydrogen