Astronomy Notes - 1 1.11.2016 Phases of the moon o Half of the moon is illuminated by the sun and half is dark o We see a changing combo of the

Astronomy Notes - 1 1.11.2016 Phases of the moon o...

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1.11.2016Phases of the moonoHalf of the moon is illuminated by the sun and half is darkoWe see a changing combo of the bright and dark faces as the moon orbits earthoPhasesFull moonWaxing gibbousFirst quarterWaxing crescentNew moonWaning crescentThird quarterWaning gibbousWhat causes eclipses:oThe Earth and Moon cast ShadowsoWhen either passes through the other’s shadow, we have an eclipseDifferent zones of shadowsoCentral core – UmbraoExtended region (outer, not as dark) – PenumbraLunar EclipsesoMore frequentoEarth casts a shadow on the moonoOccur only at full moonoLunar eclipses can be penumbra, partial, or totaloPenumbral Lunar EclipseMoon passes through penumbraoPartial Lunar EclipsePart of moon passes through umbraoTotal Lunar Eclipse Moon passes entirely through umbraSolar EclipsesoMoon casts a shadow on earth, blocks the sun from viewoSolar eclipses can occur only at new moonoSolar eclipses can be partial, total, or annularoAnnular solar eclipseMoons umbral shadow does not reach earth, an annual eclipse occurs in small central regionoPartial solar eclipseOccurs in the lighter area surrounding the area of totalityoTotal solar eclipse 1
Occurs in small central regionMost of the time when there is a new or full moon – the shadows of the moon and earth aren’t aligned oThe moon’s orbit is tilted 5 degrees to the ecliptic planeEclipses can only happen when the moon is located at one of its nodes(where the two orbital planes intersect) during new/full moon2 eclipse seasons each yearTwo conditions must be met to have an eclipse oIt must be a full moon (lunar eclipse) or a new moon (solar eclipse)oThe moon must be at or near one of the two points in its orbit where it crosses the ecliptic plane (its nodes)Size scales in the UniverseoThe Universe is fucking hugeoSpace is mostly empty – the distances between objects are vastAntipodesoEarth Circumference – 40,000 kmoAntipodeMost distant place you can travel Antipode of current location – 20,000 km awayMoon is our nearest neighboro380,000 km away from EarthoRoughly 10x more distant or one order of magnitude oOne power of 10 = one order of magnitude (just count the zeros lol)Next nearest object = Venuso43,000,000 km from the eartho100x more distant than the moon2 orders of magnitude Scientific notation used to write large numbersUnits for large length scalesoOne light-year (ly)Distance traveled by light in one yearoOne parsec (pc)Equal to 3.3 lyClosest stars are a few parsecs awayoOne kiloparsec (kpc)Equal to 1000 pcMilky way is about 8 kpc in radiuso1 megaparsec (mpc) = 10^6 pcdistance to nearby galaxies is .8 to a few mpc1.13.2016:Astronomy is a science build from lightNo earthbound labs2
Astronomers observeWavesoElectromagnetic wave/electromagnetic radiationo

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