The ABC's of Astronomy (v1.2)

A is for Astronomy, the science of far out
B is for Big Bang, how the cosmos came about
C is for Chandrasekhar, who knew things compact
D is for Dark Matter, whose existence is a fact
E is for Eddington, and matters radiative
F is for Faraday, and wave planes rotative
G is for Galaxies, that fly between voids
H is for Hubble, who knew disks from ellipsoids
I is for Ionization, revealing energy states
J is for Julian Day, for periodic dates
K is for Kepler, and his revolution
L is for Local Group, a galactic profusion
M is for Molecular Cloud, a protostellar batter
N is for Neutron Star, the densest of matter
O is for Oort Cloud, that beyond Pluto lies
P is for Photon, the coveted prize
Q is for Quasar, the most energetic
R is for Redshift, revealing the kinetic
S is for Supernova, nucleosynthesis site
T is for Telescope, gatherer of light
U is for Ultraviolet, seen only from space
V is for Virial Theorem, an equilibrium case
W is for Wolf-Rayet Star, massive and bright
X is for X-ray, where hot things emit light
Y is the fraction of helium amassed
Z is for Zenith, the highest and last.