How do we determine the distance to a neighboring Galaxy? (> distance on the order of Millions to Billions of Light-Years).
How about determining the distance to a large cluster of stars within our own Galaxy (< 100,000 L-Y)?
For measuring distance to neighboring galaxies, astronomer use inverse-square law or Hubble’ law by measuring red shift. For smaller distances, the distance can be found out by comparing a diagram of the stars’ colors and apparent brightness with a cluster whose distance is known through parallax or by comparing “variable stars” whose patterns of brightness variation is a clue to their intrinsic brightness (Sparke & Gallagher, 2007).
Why isn’t solar energy deployed more than it is today if so much of it is around? Estimate the maximum amount of solar energy that could hit a square meter of Earth at a latitude of 23 degrees North in the summer time over a period of a minute? Assume the time of day is noon where you are making your estimate.
The reason because the solar energy isn’t deployed more is that it has a massive initial cost. It is also because solar energy cannot be produced at night and it introduced additional cost for energy storage components. It can also be easily affected by pollution and bad weather. The maximum amount of solar energy that a square meter of earth can receive is 342 W/m2.