1: Science of the Universe Flashcards
To remember all the things that we need to know in Unit 1.
What did Plotemy do?
Created the geocentric model.
What is the geocentric model?
- All stars took up a space outside a sphere, and it revolved rapidly
- Planets are all on small inner circular orbits
- Sun revolves around the Earth on the 4th orbital circle.
Who came up with the heliocentric model?
Nicholaus Copernicus (Polish)
What is the heliocentric model?
He said that the sun was in the middle of the solar system, and it didn’t rotate. It was all the other planets that went around it. It was disproved many times, but still a key time in history.
What is the celestial sphere?
This sphere goes around the Earth, and has a North Celestial Pole and South Celestial Pole (similar to the locations of the North Pole and South Pole, but on the larger sphere). There is also an equator that is similar to the one on Earth.
What are the 2 different ways to locate stars?
Right Ascension-Descension and Altitude-Azimuth.
What are circumpolar stars?
These are stars like Polaris that do not set under the horizon.
What is an asterism?
An asterism is a group of stars that is not officially known as a constellation yet.
What is a constellation?
A constellation is a place in the sky.
What do constellations usually contain?
They usually contain asterisms. It’s like Ursa Major (constellation) contains the Big Dipper (asterism)
What section are radio rays on the electromagnetic spectrum?
Far right.
What section are the gamma rays on the electromagnetic spectrum.
Far left.
Why is spectroscopy important?
Visible light being shined through a prism creates a spectrum. This may help us determine motion, temperature, density, and composition.
What are the two spectrums that might tell you the property of a star?
Absorption Spectrum and Emission Spectrum
What is the Absorption Spectrum?
This is a continuous spectrum that has dark bands created when light mixes with hot and cold gas.
What is the Emission Spectrum?
This is a continuous spectrum with light bands that tells us the composition (elements) of a star.
How do you find the motion of a star?
Due to the doppler effect, the longer wavelengths are represented by the redshift; the shorter by the blueshift.
What’s a redshift caused by?
Longer wavelengths (longer distance between crest and trough)
What is a blueshift caused by?
Shorter wavelengths (shorter distances between crest and trough)
How can you tell whether a star has a high pressure or a low pressure?
Blueshift: Star is moving towards you.
Redshift: Star is moving away from you.
High atmospheric densities usually have thicker lines.
Low atmospheric densities usually have thinner lines.
What is Wien’s Law?
lambda (max) = 0.0029/temperature (in K)
What is the mnemonic to remember the class order of stars?
Oh Be A Fine Girl/Guy, Kiss Me.
What does Class O represent?
Colour: Blue
Temperature: 28000K - 50000K
Lines of helium and weak hydrogen.
What does Class B represent?
Colour: Blue-White
Temperature: 10000K - 28000 K
Lines of helium are strong with weak lines of hydrogen and calcium.