WEEK THREE: SEAONS & MOON
First day of fall – The equinox.
The sun will rise around 6am and set around 6pm ▯Everywhere on Earth.
*The celestial sphere: Review in Week 1 notes.
The Local Sky:
Zenith: The point directly above you.
Horizon: All points’ 90 from the Zenith.
Altitude: The angle above the horizon
Meridian: Due North horizon ▯Zenith ▯Due South horizon.
Because of Night and day stars aren’t always visible. However, they are always in
place, it just takes night time to be able to see them.
Circumpolar Stars – Always Visible
Lower Stars by celestial poles – “Rise & Set”
Ecliptic: The apparent path of the sun through the sky.
Equinox: Where the ecliptic intersects the celestial equator.
Solstice: An astronomical event that occurs twice each year as the Sun reaches its
highest or lowest excursion relative to the celestial equator on the celestial sphere
Zodiac: Is a circle of twelve 30° divisions of celestial longitude that are centered
upon the ecliptic: the apparent path of the Sun across the celestial sphere over the
course of the year. WEEK THREE: SEAONS & MOON
Axis of rotation: 23.5
Seasonal changes are more extreme at high altitudes.
Precession of the Equinoxes:
The Earth’s axis percusses (wobbles) once about every 26,000 years.
Precession changes the positions in the sky or the celestial poles and the equinoxes.
Polaris won’t always be the North Star
The spring equinox seen by ancient Greek in Aries, moves westward and now is
13,000 years North Pole will be facing a different year and will be more severe.
Last ice age, 15,000 years ago.
Motions and Eclipses: