Astronomy Week 3
Astronomy Week 3 EESC1150
Popular in Astronomy
Popular in Earth and Environmental Sciences
verified elite notetaker
This 4 page Class Notes was uploaded by Erin Bleck on Sunday July 17, 2016. The Class Notes belongs to EESC1150 at Boston College taught by Dr. Thomas Kuchar in Summer 2016. Since its upload, it has received 39 views. For similar materials see Astronomy in Earth and Environmental Sciences at Boston College.
Reviews for Astronomy Week 3
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 07/17/16
Notes February 2, 2016 Seasonal Stats th - Vernal (aka Spring) equinox – March 20 o Equinox – “equal night” 12 hours of daylight and 12 hours of nighttime o Start of spring in northern hemisphere, fall in southern th - Summer solstice – June 20 o Solstice – sun (sol) stands still (sistere) o Longest day in northern hemisphere, shortest in the southern o The Earth’s axis is titled toward the Sun, but we are actually farther away from the Sun than when we are in winter (summer in S. Hemisphere) - Autumnal equinox – September 22 nd o Start of fall in northern hemisphere, spring in the southern - Winter solstice – December 21st o Shortest day northern hemisphere, longest day in southern o The Earth’s axis is tilted away from the Sun, but we are actually closer to the Sun than when we are in summer (winter in S. Hemisphere) - Hemispherical bias! (North gets more direct Sun and more hours of daylight in their summer and South gets more direct Sun and more hours of daylight in their summer) o The only time that all the Earth gets the same number of hours of daylight is on the equinoxes - Shadows o Get longer as the sun gets lower in the sky (any time after the summer solstice) Longest shadow – winter solstice o Get shorter as the sun gets higher in the sky (any time after the winter solstice) Shortest shadow – summer solstice Seasons - The tilt of the axis shows the higher we see the Sun get in the summer and the lower we see the Sun get in the winter o The tilt of the axis is 23.5 degrees o 23.5 degrees and above the equator (23.5 N) = summer solstice Rotational north pole towards the Sun Sun’s beam is more concentrated during summer more heat North pole gets 24 hours of daylight South pole gets no daylight Equator gets 12 hours From north to south, daylight hours decrease o 23.5 degrees and below the equator (23.5 S) = winter solstice (when the S. Hemisphere is having their summer) Rotational north pole away from the Sun Sun’s beam is less concentrated (more spread out) during winter less heat North pole gets no daylight South pole gets 24 hours of daylight Equator gets 12 hours From north to south, daylight hours increase - During the equinoxes, the Sun is pointing almost directly at the equator o Everyone has 12 hours of daylight because rotational poles are neither towards nor away from the Sun - Seasonal changes are more extreme at high latitudes (at the poles) - The equator regions and tropics get the same amount of Sun throughout the year o Gets 12 hours of daylight o The same weather throughout the year - Distance from the Sun o We are closer to the Sun in winter than in the summer A 5 million mile distance o Variation of earth-sun distance is too small (~3%) Too small a variation and is overwhelmed by the effects of the axis tilt - The reasons for the seasons o The tilt of the Earth’s axis The light from the Sun strikes the ground more directly in the summer than in the winter thus concentrating more of the Sun’s energy (hotter in summer) The tilt causes more direct or indirect sunlight The sun spends more time above the horizon in the summer than winter resulting in longer days with more hours for heating with that direct sunlight That tilt causes us to be exposed to the sun longer Notes February 4, 2016 - If the axis tilts towards the Sun, it’s summer (N. Hemisphere) - If the axis tilts away from the Sun, it’s winter (N. Hemisphere) - The reasons for the seasons o The tilt of the Earth’s axis The light from the Sun strikes the ground more directly in the summer than in the winter thus concentrating more of the Sun’s energy (hotter in summer) The tilt causes more direct or indirect sunlight The sun spends more time above the horizon in the summer than winter resulting in longer days with more hours for heating with that direct sunlight That tilt causes us to be exposed to the sun longer - Distance from the Sun o We are closer to the Sun in winter than in the summer A 5 million mile difference o Variation of earth-sun distance is too small (~3%) Too small a variation and is overwhelmed by the effects of the axis tilt Why the axial tilt is the main reason why we have seasons! - How are the motions and positions of Earth and the Sun connected to what happens on Earth? o Earth’s rotation on its axis determines The length of the day o Earth’s orbit around the Sun determines The length of the year o The tilt of Earth’s rotational axis with respect to the plane of Earth’s orbit causes The seasons Lunar Phases - The changing phases of the Moon originally inspired the concept of the month - Some lunar facts o Mean distance = 385, 000km or 30 Earth diameters o Diameter = 3480km or 0.273 of the Earth’s o Time for New Moon to New Moon = 29.5 days Where the length of the month comes from (not a full 30 days…) When we have a New Moon or Full Moon will change from month to month - Names of the Moon phases o New Moon (no moon) o Waxing Crescent (after the New Moon; waxing because the illuminated part is growing; less than half = crescent) o First Quarter (looks like half the Moon) A quarter of the Moon’s orbit around the Earth o Waxing Gibbous (after the First Quarter; waxing because the illuminated part is growing; more than half = gibbous) o Full Moon o Waning Gibbous (after the Full Moon; waning because the illuminated part is shrinking) o Third Quarter Three quarters of the Moon’s orbit around the Earth o Waning Crescent (after the Third Quarter; waning because the illuminated part is shrinking) - When we have waxing phases, the illumination starts on the right side - When we have waning phases, the illumination stays on the left side until the very end - The side of the Moon that we see is always pointed towards the Sun o Half of the Moon is always illuminated, but we always don’t see it (depends on where the Moon is located in its orbit) o We see a New Moon when the Moon is between the Sun and the Earth o We see a Full Moon when the Earth is between the Sun and the Moon
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'