Question

1) Explain how Edwin Hubble determined that some nebula like M31 were outside the Milky Way galaxy.

2) In which region of the Milky Way galaxy does the solar system reside? Give three properties of this region.

3) Why is it unlikely that star formation is currently ongoing in our galaxy’s halo?

Please write short answers.

Answer 1

Hubble found that Andromeda was a fuzzy spiral region in the night sky. it was first assumed to be inside the milky way galaxy. Andromeda is considered ti be a nebula where stars are made. To prove Andromeda existed outisde the milky way, Hubble decided to determine its distance from Earth. He estimated that Andromeda is farther than the diameter of Earth and hence Andromeda exists outside the universe.

During this calculations, group of stars called cepheids were also discovered. Cepheids have the property of dim and brightening periodically. using this condition, distance is calculated and concluded that Andromeda consisting of nebula like M31 lie outside the Milky way galaxy.