7, astronomy Flashcards
what is the equation for mass, weight and gravity?
w = mg
weight (N) = mass (kg) x acceleration due to gravity (m/s)
how does a reflecting telescope forms an image of a distant object?
mirror that is concave
what does an eyepiece of a telescope do to the image?
magnify it
what is the evidence for and against the geocentric model?
for:
sun, moon, stars and planet move in the sky.
in the same direction.
appear to go around the earth everyday.
against:
moons of jupiter appear to go around jupiter.
movement of the sun is not exactly the same everyday.
why are telescopes that search for planets not on the earth’s surface?
planets are far away and the atmosphere is in the way
why does knowing the age of the oldest star not tell scientists the age of the universe?
the universe is older than the oldest star and a star takes times to form
what is red shift and how does it provide evidence that the universe is expanding?
red shift:
light shifts to the red end of the spectrum.
light waves are stretched to the wavelength increases.
the frequency change if a source is moving.
evidence:
red shift shows galaxies are moving away.
all galaxies show red shift.
therefore galaxies are moving apart.
what methods do we have to look for life in our solar system and other universes?
solar system:
telescopes.
evidence of conditions needed such as water and oxygen.
proves to other planets.
universes:
radio telescopes.
search for other planetary systems.
sending out messages.
what is redshift?
change in frequency of light
what is happening to the universe if some galaxies show greater redshift than others?
the universe is expanding and some galaxies are moving faster
what additional data can be collected using modern telescopes?
more wavelengths collected because telescopes are above the earth’s atmosphere
what is the life cycle of a star?
nebula:
cloud of dust and gas.
pulled together by gravity.
main sequence:
fusion.
hydrogen converted into helium.
for millions of years.
red giant:
hydrogen runs out.
star expands and gets colder.
uses up all its helium.
white dwarf:
collapses because outwards force of fusion is less than inwards force of gravity.
becomes smaller and dense.
how do different telescopes give better understanding of the universe?
more info can be collected, different waves give different info, produce magnified and clearer images
a galaxy is a collection of…
stars
why do radio telescopes not have to be placed high up on a mountain?
radio waves are not absorbed by the atmosphere
