Lecture 7 - Acient Astronomy Flashcards
(26 cards)
How were trigonometry and geometry used in early astronomy?
They were used to determine distances and positions of celestial bodies.
What did Aristarchus of Samos use geometry for?
To show the relative distances to the Moon and Sun.
How did Tycho Brahe revolutionize astronomy?
He turned it into the first “modern science” through extremely precise naked-eye measurements.
What astronomical event did Brahe identify?
Supernovae
What belief did Brahe still hold about the solar system?
That the Sun orbited the Earth.
How did Brahe’s data contribute to astronomy?
His student Johannes Kepler used it to develop Kepler’s three laws of planetary motion, which later helped Newton formulate the theory of gravity.
What does the horizon represent in astronomical coordinate systems?
It represents 0 degrees.
What is azimuth?
The angle of rotation.
What is altitude?
The height above the horizon.
What is the most important property of a telescope?
The diameter of the telescope.
What equation relates resolution to telescope diameter?
θ = 1.22 × (wavelength of light / diameter of aperture).
What happens when a telescope has a larger diameter?
It can see fainter objects, provide better resolution, and capture more photons.
What was Galileo the first to do?
Use a telescope for astronomy.
What celestial objects did Galileo observe?
Craters on the Moon, moons of Jupiter, and the phases of Venus.
What are the advantages of refractive telescopes? (LENSES)
Simple design, high resolving power.
What are the disadvantages of refractive telescopes? (LENSES)
Expensive lenses, heavy structure, long focal plane needed, unstable structure, chromatic aberration.
Who developed mirror-based telescopes? (refractive)
Newton
What are the advantages of mirror telescopes?
No chromatic aberration, larger and structurally sound, cheaper and lighter mirrors.
What are the disadvantages of mirror telescopes?
Secondary mirror can block light, slightly worse resolution compared to same-size refractors.
What is the simplest optical detector?
he human eye (eye piece).
What are photographic plates used for?
High-resolution imaging, but inefficient in capturing light (QE ~1%)
What are photomultiplier tubes?
Highly sensitive detectors that can detect signals from single photons.
What are CCDs?
Industry standard detectors used in photography, medicine, and science, with QE ~90%.
What do radio telescopes rely on?
Ground-based optical and radio telescopes.
