Unit 2.6 - The Universe Flashcards
Explain how atomic lines on atomic absorption spectra arise.
Different gases/elements in a star’s atmosphere absorb light of specific wavelengths/frequencies, so the wavelengths that are absorbed appear as dark lines,
How were 19th century scientists able to use absorption spectra to reveal the chemical composition of stars.
Since the wavelengths absorbed are specific to the elements present in the star, they knew which elements were in the stars based on the lines on the absorption spectrum.
Define the cosmological “red shift.”
The wavelenghs of the absorption lines of distant galaxies are increased and this effect increases with distance.
Explain the reason for the cosmological red shift.
The Universe is expanding, so the distance between the object emitting the light and the observers on Earth is increasing, causing the wavelength of the light to increase as it travels for a greater amount of time.
Explain how the cosmological red shift suggests that all galaxies originated from a single starting point (Big Bang)
Red shift, and hence recession velocity, increases with distance. If expansion is reversed, then everything would revert back to a single point.
Explain how the existence of Cosmic Microwave Background Radiation supports the Hot Big Bang model of the origin of the Universe.
The wavelength of the early radiation in the form of short wave (gamma) radiation increased to become the longer wave (microwave) radiation that currently pervades the Universe.
