QQC 2

Quote:  So if Pluto really is a planet it is certainly an odd one. It is very tiny:
just one-quarter of 1 percent as massive as Earth. If you set it down on top
of the United States, it would cover not quite half the lower forty-eight
states. This alone makes it extremely anomalous; it means that our planetary
system consists of four roclty inner planets, four gassy outer giants,
and a tiny, solitary iceball. Moreover, there is every reason to suppose that
we may soon begin to find other even larger icy spheres in the same portion
of space. Then we will have problems. After Christy spotted Pluto's
moon, astronomers began to regard that section of the cosmos more attentively
and as of early December 2002 had found over six hundred additional
Trans-Neptunian Objects, or Plutinos as they are alternatively
called. One, dubbed Varuna, is nearly as big as Pluto's moon. Astronomers
now think there may be billions of these objects. The difficulty is that
many of them are awfully dark. 1)Typica1ly they have an albedo, or reflectiveness,
of just 4 percent, about the same as a lump of charcoal-and of
course these lumps of charcoal are about four billion miles away.

Question: After I read this excerpt, I wondered what significant problems we would face is there were even larger icy spheres in the same portion of space.

Comment: I was surprised that Pluto was so small in terms of space. The fact that it would fit in the United States just makes me wonder if there are any other layers besides ice on it. And how they determined it was a moon and not just a ball of ice.