Tuesday 24th Aug Flashcards
What two factors determines a star’s magnitude?
The amount of light a star emits
The distance between the star and Earth
The greater the distance the dimmer the star will appear?
True
What is a star’s colour due to?
its temperature and the elements it contains
What does each star emit?
a spectrum of light across a range of frequencies, visible light, infrared or ultraviolet
How do scientists determine what elements are present in a star?
a distinctive line that appear in its spectrum, atoms absorb colours leaving dark lines on a spectra
What does the data from analysing spectra indicate?
75% of matter in typical star is hydrogen
25% is made up of helium
smaller amounts of oxygen and other heavy elements
Who is Christian Doppler?
An Austrian physicist who noticed that the frequency of a sound changes if the source of the sound is approaching or moving away
What is an example of the Doppler Effect?
when an aeroplane or train passes - Light waves from a moving source
What information can light from a star show?
the substances in the star
the movement of the star relative to the Earth
What is the meaning of redshift?
Stars moving away from earth exhibit lower frequencies
What is the meaning of blue shift?
Stars moving toward the earth exhibit higher frequencies
Light coming from galaxies shows that the majority of stars are moving…?
away from the earth
