P1 THE EARTH IN THE UNIVERSE Flashcards
What is at the center of the universe
the sun
What is nuclear fusion
When hydrogen nuclei are jamed together so hard that they combine in pairs to form the element helium
What is the increased wavelength of a galaxy called
redshift
How old is the universe?
14 000 million years ago
how old is the sun
5000 million years old
how old is the earth
4500 million years old
Why is it difficult to predict the fate of the universe?
- we can only measure the mass of those parts of the universe which emit radiation
- precise measurements of the speed and distance of galaxies is difficult because their radiation travels such a long way
What is the parallax effect?
as earth orbits the sun, nearby stars move slightly against the fixed background of distant stars
what are the uncertainties of using brightness to measure the distance of stars?
- it is based on assumption that similar types of stars
- based on estimating the distance to one of the stars
- many things make it difficult - dust, rain, clouds
What is the parallax effect?
as earth orbits the sun, nearby stars move slightly against the fixed background of distant stars
what are the uncertainties of using brightness to measure the distance of stars?
- it is based on assumption that similar types of stars
- based on estimating the distance to one of the stars
- many things make it difficult - dust, rain, clouds
what was wegeners theory based on? (evidence)
- continents fit together so well
- similar fossils and rocks are found in continents now separated by oceans
why was Wegener’s theory not accepted?
- they had simpler theories which explained his observations
- nobody could explain or measure the movement of the continents
- wegeners was not a trained geologist
what is the core mostly made of?
liquid iron
what is the mantle made of?
semi-liquid rock - floats on the core
