ASTR 1000 Lecture Notes - Lecture 3: Lunar Month, Solar Time, Full Moon
18 Jun 2018
School
Department
Course
Professor
Class 3 & 4
Annual Motion
-reflect the Earth's orbit around the Sun
-shows difference between solar day and sidereal day
-the Earth moves 1 degree everyday around the sun (during 1 day it
completes one rotation)
Solar Day
-the period of time between the instant when the sun is directly
overhead (ie. noon) to the next time it is directly overhead.
Sidereal Day
-the time needed between successive risings of a given star
-is about 4 mins shorter than the solar day — 366 days in a sidereal year
-completes an extra rotation because in the celestial sphere is rotates a bit slower
Inclination
-is a measure of how the plane of an orbit is tilted with respect to the plane of the
ecliptic. An orbit that lies on the plane of the ecliptic would have an inclination of
zero degrees; higher numbers indicate more inclined orbits. 231/2 degrees at most
northern and southern points.
-Explains why our winters are colder and summers are warmer - change in
declination, direction of sunlight/spread of sunlight
Seasons: The tilt of earth’s rotation axis relative to the ecliptic is responsible for the seasons we experience — the
marked difference in temperature between the hot summer and cold winter months.
Precession: the orientation of the earths axis changes slowly over the course of thousands of years.
Tropic of
Cancer
and
Capricor
n are 23
1/2
degrees
away
from the
equator
Celestial
Equator
is on a
slope.
find more resources at oneclass.com
find more resources at oneclass.com
Ecliptic
-the apparent path of the Sun, relative to the stars on the celestial sphere, over the course of the
year.
Zodiac
-the 12 constellations on the celestial sphere through which the sun appears to pass during the
course of the year.
Phases of the Moon
-it changes size, teeters on scale, does
not stay in one place
-cycle takes 29 1/2 days
-Synodic month: how long it takes
to get from new moon (or full moon)
to new moon (or full moon). When
the sun and moon meet in the same
arrangement. The time required for
the moon to complete a full cycle of
phases. The word month came from
moon.
-Terminator: part of the moon, the
place where the most interesting
things are seen on the moon.
Lunar Phases
-New Moon: not visible in the sky
-Waxing: getting fatter, bigger
-First Quarter moon: gone the first
quarter around its orbit, right side is
illuminated. Rises at noon, but often
only becomes visible late in the day
as the Sun’s light fades.
-Gibbous moon: more then a quarter
round/is visible
-Full moon: is visible. Rises in the east as the Sun sets in the west
-Waning: getting thinner
-Third Quarter moon: sometimes known as the last quarter moon, left side is illuminated.
Eclipses
-the event where the Sun, Earth and Moon line up precisely, but only at new or full moon.
-Lunar Eclipse: celestial event during which the moon passes through the shadow of Earth,
temporarily darkening its surface. It can only occur during the full phase.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Reflect the earth"s orbit around the sun. Shows difference between solar day and sidereal day. The earth moves 1 degree everyday around the sun (during 1 day it completes one rotation) The period of time between the instant when the sun is directly overhead (ie. noon) to the next time it is directly overhead. The time needed between successive risings of a given star. Is about 4 mins shorter than the solar day 366 days in a sidereal year. Completes an extra rotation because in the celestial sphere is rotates a bit slower. Is a measure of how the plane of an orbit is tilted with respect to the plane of the ecliptic. An orbit that lies on the plane of the ecliptic would have an inclination of zero degrees; higher numbers indicate more inclined orbits. 231/2 degrees at most northern and southern points.
