Seasons And Horizons Flashcards
method for mapping stars in space by altitude and azimuth.
Horizon System
vertical elevation of an object above the horizon
Altitude
direction of an object from the observer
Azimuth
the point in the sky directly above the observer
Zenith
the point directly below the observer
Nadir
where the sky and the surface appear to meet
Celestial Horizon
an imaginary sphere with Earth in the center
Celestial Sphere
0°
Equator
23 ½ degrees N
Tropic of Cancer
23 ½ degrees S
Tropic of Capricorn
when one of earth’s poles has reached its maximum tilt TOWARD the sun, happens once in each hemisphere (seperate times), so two in total
Summer Solstice
when one of earth’s poles has reached its maximum tilt AWAY from the sun, happens once in each hemisphere (seperate times), so two in total
Winter Solstice
also known as the spring equinox, when the sun crosses the celestial equator in the northern direction
Vernal Equinox
also known as the autumn equinox, when the sun crosses the celestial equator in the northern direction
Autumnal Equinox
Reasons for the seasons:
- Earth’s axis in relation to the celestial plane
- Earth’s orbit
- Sunlight being direct or indirect
When we are closest to the Sun on January 3rd, each year, why is it so cold?
The N axis is furthest from the sun
When is the sun highest in the sky in PA?
June
When is the sun lowest in the sky in PA?
December
When is the “shortest” day of daylight in the Northern Hemisphere?
December 21st
When is the “longest” day of daylight in the Northern Hemisphere?
June 21st
Exactly how long is one year?
365 days, 6 hrs, 9 mins and 9 secs
What is a Leap Year?
When earth’s rotation is 366 days, so we add February 29th to the calendar every 4 years
How long is one leap year?
366 days
the angle between an object’s rotational axis and its orbital axis
Axis Tilt
The point when an object is closest to the sun
Perihelion
The point when an object is furthest from the sun
Aphelion
One Earth Rotation=
24 hours
One Earth Revolution =
365 days
sunlight in which the path of light from the sun to the planet is a straight line and nothing interferes.
Direct Sunlight
sunlight in which the path of light from the sun to the planet has things that interfere.
Indirect Sunlight
Why is there a difference in energy received, between direct and indirect sunlight?
Direct sunlight is more intense than indirect since nothing is filtering it so the light provides more heat energy.
North is…
0° or 360°
East is…
90°
South is…
180°
West is…
270°
