Chapter 1 Quiz Flashcards
What is the celestial sphere?
an imaginary sphere centered on the earth and on which all celestial objects are considered to lie. everything on the sphere can be mapped out, even though everything is constantly moving; everything we see in the skys half dome
what are the various ways of mapping things on the celestial sphere? why the different methods?
1. use the horizon zenith- the imaginary point on the celestial sphere that is directly above on the top of the dome. cardinal points- N, E, S, W meridian- line of longitude running between N and S poles location of angle- azimuth (how far around) and altitude (how high up) (azimuth begins in the N at 0 degrees and continues toward E 2. Earths longitude and latitudes projected on the sphere N/S celestial poles right ascension (measure in hours, min, sec, - similar to longitude) declination (measure in degrees- similar to lattitude)
what are the daily (dinural) motions of the sun and the stars in the sky? what are they called, what causes them?
Solar day- rotational measure of the earth with respect to the sun. caused by the earths rotation around the sun; 24 hours
sidereal- rotational measure of the earth with respect to the stars. caused by the earths revolution; 23 hrs, 56 min
what is the annual path of the sun in the sky? how do we see it? how long does it take? where does it officially start?
the sun travels its yearly path on the ecliptic; we see the zodiac constellations at different times of the year and also go through seasons; it takes 365.4 days solar days; it officially starts at the vernal equinox (near constellations Lyro and Aries) around March 21st
What is the difference in how we see the daily motion of the Sun and Stars from various locations on Earth (latitudes)? What is your latitude?
if one lives near the equator the sun and stars will rise east pass overhead and set in the west, if one lives in north pole the sun and starts will rise in the east and move in a horizontal circle (never really set or rise) our latitude is 32 degrees
Where, as we see it, does the Sun rise and set every day of the year and how does that change? Why does it change
we see the sun rise int he east and set in the west. during the different seasons the sun rises at different point, winter solstice, summer solstice, autumnal and vernal equinox. these seasons change because of the tilt of the earth
winter solstice
december 22, sun rises farthest south of east and sets farthest south of west
summer solstice
june 21, the sun rides farthest north of east and sets farthest norrth of west
autunomal equinox
september 22, sun rises almost exactly at east and sets almost exactly at west
vernal equinox
march 20, sun rises almost exactly at east and sets almost exactly at west
What is the “tilt” of the Earth? What is tilted and compared to what? How does it change, if it does?
the tilt is 23.5 degrees. the earth rotation axis (poles) are tilted in relation to the ecliptic (the planes of earths orbit) depending on the time of the year and ones location, the earth is either tilted towards the sun where the sun is higher in the northern hemisphere, creating summer there (more light, higher arc) and winter in the southern hemisphere.. the earths axis of rotation changes slightly over many years
How is the tilt responsible for the seasons? What happens as we observe it on Earth (the “double effect” of duration and angle), and what is the Astronomical-Physical explanation for it what we observe?
The Earth’s axis is tilted perpendicular to the plane of the ecliptic. The Earth’s axis tilts towards the sun in different times throughout the year. During the summer it is more hot because of the more direct angle of the Sun hitting the Earth. During the winter the Sun hits the Earth at a more extreme and shallow angle.
What are the moon’s rotation and revolution? How long does each take? How does that explain what we see every night and during the entire cycle?
Moon’s rotation = moon makes a complete 360 degree turn on its axis
Moon’s revolution = moon travels west to east around Earth
Both rotation/revolution take the same amount of time (approx. 27.3 sidereal days/29.5 solar days)
As the moon moves around earth it changes position to the background stars and to the sun. The earth changing position around the sun creates the phases of the moon we see.
What are the phases of the moon (name, order, direction) and what causes them
new moon, waxing crescent moon, 1st quarter moon, waxing gibbous moon, full moon, waning gibbous moon, third quarter moon, waning crescent moon, New moon. The moon’s position relative to that of the sun changes so we see lunar phases.
What is the Sidereal month, and what is the Synodic month? How is each measured, how long is it and why? Which one do we typically use?
The sidereal month is the time it takes for the Moon to complete one full orbit of 360 degrees around the Earth, determined by the location of the Moon in its orbit around Earth as measured with respect to the stars; takes approx. 27.3 days
The synodic month is the time it takes the Moon to complete one cycle of phases (i.e. from new Moon to new Moon or from full Moon to full Moon), thus measured by the Sun rather than the stars; Caused by Earth orbiting the Sun while the Moon goes through its phases; 29 ½ days
