Why can't a star's distance be determined solely from its apparent brightness in the sky? (a) stars move too fast (b) stars burn out before we can determine their distance (c) stars have different energy outputs (d) there's no way to measure the light from a star (e) earth's atmosphere blocks all starlight

(C) stars have different energy outputs

Explanation:

All the stars that we see in the Universe are not of the same size and brightness. Also, they are not situated at the same distance from us. If all the stars had been of the same size and luminosity, we could have determined their distance with the help of their apparent brightness. Also there can be two stars of equal size but their apparent brightness might be different. The brightness depends on the size and the age of the stars. There can be a very bright star which looks very faint to us just because its farther in comparison to other stars.

Hence, we can not rely solely on the apparent brightness of the stars as they have different energy outputs.

so here is the information for current research:

-nrel's geothermal analysts, scientists, and engineers perform a full range of research from developing advanced methods of locating and accessing geothermal resources to exploring innovative technologies to extract and produce clean energy from the heat of the earth

and here is the information for the technology of geothermal energy:

-it's clean and sustainable

-resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma

-almost everywhere, the shallow ground or upper 10 feet of the earth's surface maintains a nearly constant temperature between 50° and 60°f (10° and 16°c)

-geothermal heat pumps can tap into this resource to heat and cool buildings

-a geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building

-in the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system

-in the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger

-the heat removed from the indoor air during the summer can also be used to provide a free source of hot water

the answer is 12 as i may remember

: )