Astronomy and Space Science

Page
10

Attempts to measure the distance to the planets were not successful at the time. In the geocentric models, the radii of deferent and epicycle of a planet are not obtained from observations (angle and time), only their ratios. Since the radii of planetary epicycles are the same as Earth’s orbital radius in the heliocentric model, Copernicus was able to determine the orbital radii (relative to Earth orbit) of all six planets.

Heliocentric models predict stellar parallax, which is exactly why Tycho did not accept the heliocentric model. He could not observe parallax for stars, which are much further then he thought, and have a much smaller parallax (<1”) than he could measure.

A: Easier to compute, correct orbital radii, predicts stellar parallax.

More:

Slide 47

What is the role of human/Earth in cosmology?

Earth is the center of the universe

Earth is slightly off the center of planetary orbits. (Ptolemy)

The Sun is the center of the universe

The Sun is one of the stars in the Milky Way Galaxy

The Milky Way Galaxy is just one of the galaxies

The universe has no center

We are not even made of the dominant form of matter (see nonbaryonic dark matter)

The universe is made up of more energy (in the sense of E/c2) than matter (see dark energy).

A: It has been decreasing since history.

More:

Here are some paradigm shifts:

Slide 48

Q: How can I understand different designs of telescopes?

A:

Slide 49

Can you suggest some equipments for schools?

A: Different schools have different needs due to their programs, location, budget, number of students, etc. It is important to know if the equipments are for visual or imaging work, or for inspiration. The following are just some possible equipment choices, popular in the amateur astronomy community, and are benefited by cost saving due to mass productions:

Small high quality refractors with small equatorial or alt-az mounts: best image quality, very versatile, most expensive. A compromise is to have a small one for portable and frequent uses. Good for planet/solar/lunar visual observations, wide field imaging. (Front Solar filter required for solar observations thru the telescope.)

Medium size catadioptrics with GOTO mounts: reasonable price, reasonable image quality, but a bit low in contrast and have narrower field, very powerful when combined with a GOTO and tracking system. Good for high power imaging or general purpose visual observations.

Large reflectors with dobsonian mounts: cheap for the size, good image quality, but no tracking. Their large sizes allow observation of dimmer objects.

Slide 50