The Cosmic Perspective: Discovering the Universe for Yourself (Chapter 2) Flashcards
The angular east-west distance between the prime meridian (which passes through Greenwich, England) and a location on Earth’s surface
Longitude
Refers both to the point on the celestial sphere where the ecliptic is farthest south of the celestial equator and to the moment in time when the Sun appears at that point each year (around December 21st) - People living in the Northern Hemisphere
Winter Solstice
An event that occurs when the Moon passes through Earth’s shadow, which can only occur at a full moon
Lunar Eclipse
The imaginary sphere in which objects in the sky appear to reside when observed from Earth
Celestial Sphere
The phase of the Moon that occurs one-quarter of the way through each cycle of phases, in which precisely half of the visible face is illuminated by sunlight
First-Quarter Moon Phase
The two points in the Moon’s orbit where it crosses the ecliptic plane
Nodes (Of Moon’s Orbit)
The apparent motion of a planet during the period of a few weeks or months when it moves westward relative to the stars in our sky
Apparent Retrograde Motion
A star that always remains above the horizon for a particular latitude
Circumpolar Star
1/60 of 1 Degree
Arcminute
One of the two coordinates needed to pinpoint an object in the local sky
Direction (in local sky)
The point on the celestial sphere directly above Earth’s South Pole
South Celestial Pole
A solar eclipse during which the Sun becomes only partially blocked by the disk of the moon
Partial Solar Eclipse
The set of phases in which more of the visible face of the Moon is becoming illuminated; the phases that come after the new moon but before the full moon
The Waxing Phases
Refers both to the point on the celestial sphere where the ecliptic is farthest north of the celestial equator and to the moment in time when the Sun appears at that point each year (around June 21st) - People living in the Northern Hemisphere
Summer Solstice
The phase of the Moon (or a planet) in which just a small portion (less than half) of the visible face is illuminated by sunlight
The Crescent Moon Phases
The imaginary sphere on which objects in the sky appear to reside when observed from Earth
Celestial Sphere
A half-circle extending from your horizon (altitude 0 degrees) due south, through your zenith, to your horizon due north
Meridian
A region of the sky; 88 official constellations cover the celestial sphere
Constellation
A solar eclipse during which the Moon is directly in front of the Sun, but its angular size isn’t large enough to fully block the Sun; thus a ring (or annulus) of sunlight is still visible around the Moon’s disk
Annular Solar Eclipse
The phase of the Moon that occurs three-quarters of the way through each cycle of phases, in which precisely half of the visible face is illuminated by sunlight
Third-Quarter Moon Phase
The lighter, outlying regions of a shadow
Penumbra
Periods during which lunar and solar eclipses can occur because the nodes of the Moon’s orbit are aligned with Earth and the Sun
Eclipse Seasons
An object that orbits a planet
Moon
The angular distance between the horizon and an object in the sky
Altitude (above horizon)
A boundary that divides what we can see from what we can’t see
Horizon
The apparent shift in the position of a nearby star (relative to distant objects) that occurs as we view the star from different positions in Earth’s orbit of the Sun each year
Stellar Parallax
The portion of a total lunar eclipse during which the Moon is entirely within Earth’s umbral shadow or a total solar eclipse during which the Sun’s disk is entirely blocked by the Moon
Totality (Eclipse)
A lunar eclipse in which the Moon becomes fully covered by Earth’s umbral shadow
Total Lunar Eclipse
1/60 of an arcminute, or 1/3600 of 1 Degree
Arcsecond
The meridian of longitude that passes through Greenwich, England; is defined to be longitude 0 Degrees
Prime Meridian
The gradual wobble of the axis of a rotating object around a vertical line
Precession
The extension of Earth’s equator onto the celestial sphere
Celestial Equator (CE)
The period over which the basic pattern of eclipses repeats, which is about 18 years and 11 1/3 days
Saros Cycle
The phase of the Moon in which more than half but less than all of the visible face is illuminated by sunlight
The Gibbous Moon Phases
The set of phases in which less and less of the visible face of the Moon is illuminated; the phases that come after the full moon but before the new moon
The Waning Moon Phases
The sky as viewed from a particular location on Earth (or another solid object)
Local Sky
The point directly overhead, which has an altitude of 90 Degrees
Zenith
One of the two coordinates (the other is altitude) is needed to pinpoint an object in the local sky
Direction (in local sky)
The point on the celestial sphere directly above Earth’s North Pole
North Celestial Pole (NCP)
Motion that’s backward compared to the norm
Retrograde Motion
A solar eclipse during which the Sun becomes fully blocked by the disk of the Moon
Total Solar Eclipse
A lunar eclipse during which the Moon passes only within Earth’s penumbral shadow and doesn’t fall within the umbra
Penumbral Lunar Eclipse
Direction around the horizon from due north measured clockwise in degrees
Azimuth
A measure of the angle formed by extending imaginary lines outward from our eyes to span an object (of the space between two objects)
Angular Size/Angular Distance
The angular north-south distance between Earth’s equator and a location on Earth’s Surface
Latitude
The rotation of an object that always shows the same face to an object that it’s orbiting because its rotation and orbital periods are equal
Synchronous Rotation
The Sun’s apparent path among the constellations
Ecliptic
A lunar eclipse during which the Moon becomes only partially covered by Earth’s umbral shadow
Partial Lunar Eclipse
The state is determined by how atoms or molecules are held together; the common phases are solid, liquid, and gas
Phases of Matter
An event that occurs when the Moon’s shadow falls on Earth, which can occur only on a new moon (May be total, partial, or annular)
Solar Eclipse
The state is determined by the portion of the visible face of the Moon (or a planet) that is illuminated by sunlight
Phase (of the Moon or a planet)
The apparent shifting of an object against the background due to viewing it from different positions
Parallax
The constellations on the celestial sphere through which the ecliptic passes
Zodiac
The dark central region of a shadow
Umbra
Refers both to the point in Virgo on the celestial sphere where the ecliptic crosses the celestial equator and to the moment in time when the Sun appears (around September 21st) - People living in the Northern Hemisphere
Fall Equinox
Refers to the point in Pisces on the Celestial Sphere where the ecliptic crosses the celestial equator and to the moment in time when the Sun appears (around March 21st) - People living in the Northern Hemisphere
Spring Equinox
