Stars and Galaxies conceptual review questions, part I 1) The speed of light is

Question

Stars and Galaxies conceptual review questions, part I 1) The speed of light is very fast, but it still takes light a long time to travel across the vast distances of the universe. What does this mean about the age of the universe compared to how far we look? What if the speed of light were infinite? ) An alien civilization on a planet 20 light years away fires a destructo-ray of gamma rays at Earth in 2018. At the same time, another faction of (friendlier) aliens on the same planet (long story, don't ask) sends a radio warning message to us. Which arrives at Earth first? What year(s) do the messages arrive? you have a photovoltaic cell (solar panel) 1 meter on a side and want to generate as much electricity as possible with it. Where should you stand in the solar system? Cost is not an issue, you can fly where ever you w a blue Giant 4) Name at least two pieces of evidence that fusion is occurring in the core of the Sun. oloes not collopse on telp 5) What would we observe if all fusion in the Sun ceased tomorrow? What would we observe In one million years?Thean we u 10,4 vede SS The mass of one helium atom is 0.7% less than the mass of the four hydrogen atoms which go into making it, Imagine that itwee instead 07% greater. What would happen? 7) Why do hot stars have so few absorption lines in their spectra? 8) Why do we put telescopes in space when it costs ior as much to do?

Explanation / Answer

2 ) gamma and radio waves both are EM waves and travels at speed of light .Both gamma ray burst and radio alert will arrive together after 20 years in year 2038.

3)At a safe distance from most intense star (more photons emitted,assuming frequency of photons are above threshold )

5) we may not notice with naked eye for some time (years) but in due time it's core will compress while surface area still increasing , becomes a red giant.

6) true .(not possible) Reduced mass is converted to energy.

7)If star is very hot,hydrogen in its cloud is already ionised and has no electrons in outer shell to absorb any sort of wavelength.

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