Why was stellar parallax not measured until the 19th century? ...

[APUS57]

Why was stellar parallax not measured until the 19th century?
 
  What will be an ideal response?

Question 2

Mars is often called a midway world, similar in some respects to Earth, and in others to our Moon. Explain.
 
  What will be an ideal response?

[leahchrapun]

Answer to Question 1

Stars are so far away that even the closest stars have parallax less than an arcsecond, which could not be measured without the technological developments that did not occur until the 19th century.

Answer to Question 2

Like our Moon, much of Mars is ancient cratered terrain, and its density is closer to that of the Moon than Earth. But like us, Mars has seasonal variations, polar caps, clouds, an atmosphere, dust storms, and signs of past liquid water and erosion.

[APUS57]

Thanks for the timely response, appreciate it

[juliaf]

Great answer, keep it coming