Observational Evidence Against the Geocentric Model

First observational evidence against geocentric model

Some planets were observed to undergo phases, like the Moon does.

Galileo's telescope observation of Venus

Venus goes through all of the phases (crescent, gibbous, etc.)

Spectroscopy in astronomy

They measure the widths of emission and/or absorption lines in a star's spectrum.

Telescopes for low-energy light detection

Radio telescopes

Effect of doubling telescope's primary mirror size on resolution

get better by a factor of 2

Composition of light

electric & magnetic fields

Regions of the light spectrum by energy

Gamma Rays → X Rays → Ultraviolet → Visible → Infrared → Radio

Black-body radiation and star measurement

temperature

Power increase with tripled temperature

increase by a factor of 81 (81x)

Electron transition and light emission

emits light

Telescope resolution measurement

A telescope's resolution is measured in units of arcseconds.

Resolution of a telescope

Depends on the size of the telescope and the wavelength of light being observed.

Kelvin temperature scale

Sets the point where all thermal motion stops equal to a temperature of 0.

Temperature of an object

A direct measure of the amount of microscopic motion within it.

Color of the coolest stars

Appear red.

Constant of a visible light wave

The speed is constant, regardless of the color.

Refracting telescope

Uses lenses to focus light.

X-ray telescope placement

Must be placed in outer space because Earth's atmosphere is opaque to X-rays.

Brightness comparison through filters

Can measure the temperature of a star.

Energy associated with green light

For an electron transition from n=4 to n=2 in hydrogen, it is 10.2 eV.

Type of spectrum produced by the Sun

Continuous (black-body) spectrum.

Wavelength peak of black-body spectrum

If the object's temperature doubles, the peak would be at 300 nm.

Movement indication from light source

If the measured wavelength of green light is 488.5 nm, it is moving away from you.

Spectrum observation above Earth's atmosphere

Would show slightly fewer absorption lines compared to ground-based observations.

Dark lines in observed spectrum

Reveal the chemical composition of the cool gas in front of a hot light bulb.