Astronomy Chapter 1

constellationsa human grouping of stars in the night sky into a recognizable pattern
celestial spherea canopy of stars resembling as astronomical painting on a heavenly ceiling
The star Polarisbetter known as the Pole Star or North Star
celestial polesthe points where Earth’s axis intersects the celestial sphere are called the north and south
celestial equatormidway between the celestial poles lies the equator representing the intersection of Earth’s equatorial plane with celestial sphere
Day to day changesthe stars position in the sky do not repeat themselves exactly from one night to the next
sidereal daythe time needed between successive risings of a given star
solar daythe period of time between the instant when the sun is directly overhead (noon) to the next time it is directly overhead
sidereal monthtime required for the moon to complete one trip around the celestial sphere
sidereal yearis slightly longer than the tropical year, and the constellations migrate around the calendar over the course of thousands of years
Earth moves in two ways simultaneously:1. rotates on its axis
2. while at the same time revolving around the sun
Each time Earth turns once on its axis, it also moves a small distance along its orbit about the Sun. Earth, therefore, has to rotate through slightly more than 360 degrees for the Sun to return to the same apparent location.
eclipticbecause of Earth’s orbital motion, the Sun appears to move relative to the background stars over the course of the year, tracing out a path on the celestial sphere
summer solsticeThe points on Earth’s orbit here our planet’s North Pole comes closest to pointing in the direction of the sun or equivalently, where the sun is at its northernmost point above the celestial equator (June 21)
winter solsticeSix months later, the North Pole points farthest from the Sun or the Sun is at its southernmost point below the celestial equator (December 21)
seasonsThe tilt of Earth’s rotation axis relative to the ecliptic causes
The universeWhich of the following can be described as the totality of all space, time, matter, and energy?
Vanished StarsMost of the chemical elements that make up our bodies come from
Which of the choices below correctly lists things in order from largest to smallest?Universe, Milky Way, Solar System, Sun, Earth
TrueThe distances to bodies in the solar system are a few light minutes to light hours.
A “light-year” is a unit used for what kind of measurement?Distance
A few thousands (2000-3000)About how many stars are visible on a clear, dark night with the unaided eye alone?
88Into how many constellations is the celestial sphere divided?
North PoleWhere on Earth would you be if Polaris were directly overhead?
TrueOnly at the equator are all the stars visible over the course of the year.
TrueOver the course of a night, Polaris moves less than any other visible star in the sky.
yearthe time it takes for Earth to complete an orbit around the Sun
North PoleWhere would you be if the Sun sets for six continuous months, beginning about September 23rd?
EclipticWhat celestial line is a product of the Earth’s orbit around the Sun?
Vernal and autumnal equinoxesNight and day have approximately equal length at what time or times of the year
Earth’s axis of rotation is perpendicular to the line joining Earth to the Sun, so day and night are of equal length
Spring equinoxThe Sun rises due east today, but will rise slightly north of due east tomorrow
summer solsticelongest day (most daylight) of the year
the noontime Sun reaches its highest point of the year
fall equinoxthe Sun had declination 0 degrees today, but will have a negative declination tomorrow
winter solsticeThe sun crosses the meridian 23.5 degrees lower in altitude than the celestial equator
the noontime Sun casts the longest shadows
sunset occurs at its farthest point south of due west for the year
first quarter moonit is the half moon of the evening sky
it is the highest in the sky at sunset
it rises about noon
it occurs about a week after new moon
Why aren’t there lunar and solar eclipses every month?The Moon’s orbit is inclined 5 degrees to the ecliptic.
Why is a synodic month (the time needed to complete one cycle of lunar phases) longer than a sidereal month (the time taken by the Moon to complete one orbit around Earth) and not shorter?Because Earth is moving in its orbit around the Sun in the same angular direction while the Moon orbits Earth
Which of the following types of eclipses will NEVER be observed?An annular lunar eclipse
A solar eclipse can only happen during anew moon
A lunar eclipse can only happen during afull moon
If you are in the Moon’s umbral shadow, then you will witnessa total solar eclipse
What conditions are necessary for a total solar eclipse?new moon on ecliptic near perigee
TrueAt apogee, the Moon is at its farthest from the Earth and thus appears larger than normal. Because of this, it can produce total solar eclipses, but not annular solar eclipses.
annular eclipseA solar eclipse that occurs when the new moon is too far from Earth to completely cover the Sun can be either a partial solar eclipse
total lunar eclipseAnyone looking from the night side of Earth can, in principle
penumbraDuring some lunar eclipses, the Moon’s appearance changes only slightly, because it passes only through the part of Earth’s shadow
total solar eclipsecan occur only when the Moon is new and has an angular size larger than the Sun in the sky.
umbraA partial lunar eclipse begins when the Moon first touches Earth’s
nodeA point at which the Moon crosses Earth’s orbital plane
Modern scientific theories areelegant, testable, simple, and continuously tested
An effective theorymust be continuously tested
a defining characteristic of scientific theories?must be continually tested
should be as simple as possible to explain the facts
they must be testable through experimental verification