How has the chemical composition of the core of the Sun changed ...

[jessicacav]

How has the chemical composition of the core of the Sun changed in the past 4.5 billion years? Are earthlings (if any) likely to freeze in another 4-5 billion years? Explain.
 
  What will be an ideal response?

Question 2

Should we expect to find abundant amounts of gold and other rare-earth elements elsewhere in the universe?
 
  What will be an ideal response?

[jaykayy05]

Answer to Question 1

The core of the Sun had an initial composition of 90 hydrogen and 9 helium. As hydrogen fusion has continued over the past 4.5 billion years the amount of helium produced has steadily increased. The center of the core now has about 85 helium and very little hydrogen. As a main sequence star the Sun will continue to brighten slowly. In another 4-5 billion years the Sun will have a core dominated by helium. This will force it to change into a red giant. Therefore, the Sun will only continue to brighten over time and the Earth will only get hotter, never colder.

Answer to Question 2

Gold, platinum, and other rare-earth elements are produced during the highly energetic, cataclysmic mergers of neutron stars. Because binary systems of neutron stars are rare, we do not expect an abundance of these elements.

[jessicacav]

Excellent

[bbburns21]

Gracias!