Earth-centred Universe Flashcards
How long is a sidereal day and what reference frame is it in?
23hr 56min, A complete rotation of the Earth with respect to the stars.
How long is a solar day?
24hr, a complete rotation of the Earth with respect to the Sun.
What way is the celestial sphere rotating for you?
Anti-clockwise looking north.
What are the fixed points of the celestial sphere?
North celestial pole and the South celestial pole.
Where can you find the pole star?
At the same angle above your northern horizon as your latitude.
How many regions is the sky divided into today and what can they be called ?
88 regions known as costellations
What positions are used to locate celestial bodies in the sky?
Declination and right Ascension
What are the steps for scientific method?
-Recognize a problem, by doing observations
- Make a hypothesis
- Predict the consequences of the hypothesis
- Perform experiments to test predictions
- Find a rule that leads to a theory
What is the criteria for Scientific model
Does the model fit the data?
Model must make predictions that can be tested and that it must be possible to disprove the model.
It should require the fewest assumptions.
What is parallax?
The apparent shifting of nearby objects with respect to distant ones as the position of the observer changes.
What is stellar parallax?
The apparent annual shifting of nearby stars with respect to background stars, measured as the angle of shift.
What is the parallax angle?
Half of the angle shift measured in half a year.
What did the Greeks predict?
The Earth being spherical: during lunar eclipses the edge of the Earth’s shadow is always circular.
What did Aristarchus do?
First person to propose the new heliocentric idea and estimated sizes of the Moon and Sun.
What was the purpose of Ptolemy’s geocentric model?
To account for the positions of all heavenly bodies.
