Astronomy and Space Science

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(Note: He became blind in his last years, due to observing the Sun directly through the telescope without proper filter or projection.)

Galileo’s telescopes are quite unimpressive by today’s standard, with 0.5-1 inch effective objective aperture, about 15-20x power, and a very narrow (15’) field of view, not to mention significant aberrations. But they were the best at the time.

A: No. But Galileo did designed and made his own telescopes, and improved on

them. He was ahead of others by a few months in telescope quality, enough for

him to claim most of the discoveries.

Slide 40

Was Galileo jailed?

A: He was found guilty in his trial and sentenced to jail for life. However, his treatment was closer to house arrest. He worked and published during this time.

More:

Some ideas Galileo held, such as the Earth moves around the Sun, the celestial bodies are not perfect, the Bible was not meant to teach science, etc., were considered heresy at the time. A less fortunate astronomer named Giordano Bruno was burned at the stake. To understand why Galileo was treated leniently, perhaps one should understand that Galileo was well known not only to those who practice science, but to influential people of the society and even to the Church. He made many discoveries such as the law of motion, measured gravity, invented a thermometer, studied the pendulum, etc. The physics taught at the time stress qualitative arguments, Galileo however believed in the importance of mathematics and experiments. He was thus called the “father of modern science”. What made him stand out from other scientist of his time, was the skill of mixing of theory and practice. Galileo was also very successful in getting supports from many people. Although there were people who refused to even look though the telescopes, Galileo succeeded in introducing the telescopes to many nobles and military officials who quickly understood the practical and military applications of the telescope.

Slide 41

Does the discovery of phase of Venus disproves the geocentric theory?

A: No. Models, such as Tycho’s model, which require the Venus and Mercury to revolve around the Sun give the correct phase of Venus.

Slide 42

What is a planet?

A: Definition by the International Astronomical Union (IAU) in 2006:

(1) A planet is a celestial body that

(a) is in orbit around the Sun,

(b) has sufficient mass for its self-gravity to overcome rigid body forces so

that it assumes a hydrostatic equilibrium (nearly round) shape, and

(c) has cleared the neighborhood around its orbit.

A “dwarf planet” is a celestial body that satisfies, (a) and (b) but not (c), and is not a satellite.