AST study

AST study - Angular measurements- we talk about things in...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Angular measurements- we talk about things in angular size - 1 degree= 60 arc minutes 1 arc minute= 60 arc seconds (more useful for things so tiny) - Diameter of moon is 1/2 degrees, same diameter of sun = lunar and solar eclipse because they appear the same size To convert degree and arcs to a physical measure or figure out how much energy something is giving off you need the distance Convert through Trig: tangent x = diameter/ distance 1 AU= 1 earth to sun distance. .. use in solar system 1 AU= 8 light minutes. .. use outside of solar system; generally used for distance between stars Light travels at 3.0x10^5 km/sec. .. nothing goes faster. .. allows us to “look back in time” earth rotates once on its axis every 23 hrs and 56 min, but it takes 4 min a day for earth to move around sun, solar day = sunset to sunrise 24 hrs sidereal day= star rise to star rise 23 hrs and 56 min Every 6 months the set of stars in the plain of the solar system rotates the north star (due north) is in the sky year round winter= sun is in the southern sky at -23 degrees summer= sun in norther sky at +23 degrees spring and fall when sun= 0 degrees Longitude goes from 0-360 east to west . .... right ascension Latitude goes from +90 to -90 north and south . .... declination Moon reflects the sun’s light and orbits around the Earth Lunar calendar is 29 days Magnitude measures brightness, each is 2.5 time fainter then the next Sun= -26 magnitude Faintest the human eye can see is magnitude 6= (2.5)^6 Numbers go up brightness goes down Depends on how far away a star is and how much energy the star gives off Luminosity= energy/second Twinkling depends on size, temperature, and air density. .. less atmosphere less distortion Strongest to weakest: 1) strong force (nuclear force), short range 2) weak force, short range 3) electromagnetic force (between + and -), long range force 4) gravity, long range (nothing cancels it out); not just a good idea, it’s a law Copernicus- geometrical model of the solar system - wanted only 1 set of circles since the ptolemaic system was not “pleasing to the mind” - found that it was explained well with sun at center - predicted Jupiter and Saturn conjunction by 10 days Success- simplified systems, provided a natural explanation for retrograde notation, and reveled a new order Failure- did not predict observations any better than old model
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Brache- accurate naked eye observations of planetary positions - showed heaven changed beyond moon; Nova 1572
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/18/2011 for the course AST 10G taught by Professor Lloydknox during the Spring '09 term at UC Davis.

Page1 / 5

AST study - Angular measurements- we talk about things in...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online