Class 4, ICA #3, August 31.

We had 2 clicker questions based
on the "Powers of Ten" short.


Clicker Question #1:

(Pick the correct statement.)

E. Once we see the whole Milky Way, the Sun is an invisible speck.

Why: A can't be right because you have to have moved many lightyears
before the stars start to move. B can't be right because when we
see the whole Solar System, the planets themselves are just
invisible specks. C can't be right because when we zoom-out to
see the whole Galaxy, we're clearly off to the side. D can't
be right since the Solar System is just a few tens of AU wide
but the whole Milky Way is 100,000 ly, many steps bigger.



Clicker Question #2:

The zoom-out stops at about 100 million light years because

B. that's how far we could see with 1970s technology.

Why: Recall that the Observable Universe extends about 14 billion
light-years away from us.