Mapping the Universe Flashcards
How does parallax make closer stars appear to move over the course of a year?
Distant stars are so far away they appear not to move, whereas closer stars compared with these distant stars show a relative movement from either side of the Earths orbit, as we view the stars from a different angle
How far away is a star if it has a parallax angle of one second of arc?
The star is 1 parsec away
How long is a parsec?
3.26 light years
What affects the luminosity of a star?
It’s temperature and size
What is unique about a cepheid variable star’s brightness?
It pulses in brightness over a course of periods
How can we estimate the distance to cepheid variable stars?
Using a graph of collected known distances and periods we can plot the period of a cepheid variable and make an accurate estimate as to the distance
How has the study of cepheid variable stars played a large role in determining the scale of the universe?
Previously other galaxies in our sky were presumed to be gas clouds but the discovery of the distance of the stars in these spiral nebula showed that they were too far away to be in our galaxy and further away than previously believed to be possible
What was the main issue in the Curtis-Shapley debate and what did the different sides believe?
There was debate as to what spiral nebula in the sky were.
Curtis thought they were distant galaxies and ours wasn’t the only one.
Shapely thought they were nearby small gas clouds, and that our galaxy was the only one and bigger than it is
How many parsecs are there in a megaparsec?
What are megaparsecs used to measure?
There are 1 million parsecs in a megaparsec,
They are used to measure intergalactic distances
What is the equation for speed of recession?
Speed of recession (km/s) = hubble constant * distance (km or Mpc)
How long ago do scientists believe the universe began and with what?
With a “big bang” about 14000 million years ago
