Astrology vs. Astronomy

Which one is science?

astro - star

-logy – study of

-nomy – arrangement, law

Calendars – based on astronomical movements

Day – Earth’s rotation (spinning)Month – moon orbits Earth (approx.)Year – Earth revolves around sun

Early AstronomersEarly Astronomers

Ptolemy – thought Earth was center of the universe

geocentric

CopernicusCopernicus-determined that the Sun is the center of

the solar system

Tycho Brahe – made very precise observations.Thought moon and sun revolved around Earth, but other planets around the sun.

Johannes KeplerJohannes Kepler

Used Brahe data to determine that the planets revolve around the sun in elliptical orbits. The sun is not in the exact center.

Galileo GalileiGalileo Galilei

One of the first to use a telescopeOne of the first to use a telescopeDiscovered Discovered

Craters and mountains on moonCraters and mountains on moon4 moons of Jupiter4 moons of JupiterSunspots on the sunSunspots on the sunPhases of VenusPhases of Venus

Isaac NewtonIsaac Newton

-described the force of gravity which depends on the mass of the objectsand the distance between them

-explained observations of other astronomers

Edwin HubbleEdwin Hubble

-Proved galaxies exist beyond our ownMilky Way

Optical TelescopesOptical Telescopes

RefractingRefracting Set of lensesSet of lenses Not perfect focusNot perfect focus Lens can’t be very Lens can’t be very

largelarge

ReflectingReflecting Uses curved mirrorUses curved mirror Can focus perfectlyCan focus perfectly Flaws do not affect Flaws do not affect

focusfocus Can be very largeCan be very large Preferred by Preferred by

astronomersastronomers

Where is the best place Where is the best place to put a telescope?to put a telescope?

On mountain to avoid light and air pollutionOn mountain to avoid light and air pollutionDry areas to avoid moisture problemsDry areas to avoid moisture problemsSpace – to avoid all those problemsSpace – to avoid all those problems

Light YearLight Year

Unit of distance not timeUnit of distance not timeLight travels 946,000,000,000,000 km in a Light travels 946,000,000,000,000 km in a

yearyearWe can observe objects 10 billion light We can observe objects 10 billion light

years awayyears away

Artificial Satellites

Military Weather Communication

Space ProbesSpace Probes

Uncrewed vehicle that carries instruments Uncrewed vehicle that carries instruments to planets or other bodies in spaceto planets or other bodies in spaceLuna 9 (1966) – moonLuna 9 (1966) – moonVenera 9 (1975) – VenusVenera 9 (1975) – VenusVikings (1975) – MarsVikings (1975) – MarsStardust (1999) – cometStardust (1999) – comet

People in SpacePeople in Space

11stst person – Yuri Gagarin person – Yuri Gagarin11stst American – Alan Shepherd American – Alan Shepherd11stst person on moon – Neil Armstrong person on moon – Neil Armstrong11stst American woman – Sally Ride American woman – Sally Ride

TragediesTragedies

1986 Challenger Explosion just after 1986 Challenger Explosion just after takeofftakeoff

Columbia Explosion – upon reentryColumbia Explosion – upon reentry