Chapter 2 - Discovering The Universe Flashcards
Ecliptic
The path the Sun follows as it appears to follow around the celestial sphere
Angular size
The angle it appears to span in your field of view
Angular distance
The angle that appears to separate two objects
Lunar eclipse
When the Earth lies directly between the Sun and Moon
Solar eclipse
When the moon lies directly between the Sun and Earth
Constellation
A region of sky with well-defined borders
The familiar patterns of stars merely help locate constellations
Horizon
A boundary that divide what we can see from what we cannot
We can pinpoint any object in the local sky by stating its ____________ along the horizon and its _____________ above the horizon.
(direction),
(altitude)
(We can pinpoint any object in the local sky by stating its direction along the horizon and its altitude above the horizon. )
There are 60 ________ in a degree.
(arcminutes)
What does it mean for stars to be circumpolar?
Stars near the north pole are circumpolar, meaning they remain perpetually above the horizon, circling around the north celestial pole each day
Prime meridian
The line along which longitude is defined to be 0° (and passing through Greenwich, England)
The altitude of the celestial pole in your sky is equal to your _______.
(latitude)
Procession
A gradual wobble that alters the orientation of Earth’s axis in space
Each cycle of Earth’s procession takes about ________ years.
(26,000)
Synchronous rotation
The rotation of an object that always shows the same face to an object that it is orbiting because its rotation period and orbital period are equal
Phase(of matter)
The state determined by the way in which atoms or molecules are held together; the common phases are solid, liquid, and gas
Crescent phase
The phase of the moon (or of a planet) in which just a small portion (less than half) of the visible face is illuminated by sunlight
South celestial pole (SCP)
The point on the celestial sphere directly above Earth’s South Pole
Apparent retrograde motion
The apparent motion of a planet, as viewed from Earth, during the period of a few weeks or months when it moved westward relative to the stars in our sky (due to the fact that Earth is “passing it up” in orbit)
Moon
An object that orbits a planet
Eclipse seasons
Periods during which lunar and solar eclipses can occur because the nodes of the Moon’s orbit are aligned with Earth and the Sun
North celestial pole (NCP)
The point on the celestial sphere directly above Earth’s North Pole.
Penumbra
The lighter, outlying regions of a shadow (the place where sunlight is only partially blocked)
Umbra
A central place where all sunlight is blocked
Nodes (of Moon’s orbit)
The two points in the Moon’s orbit where it crosses the ecliptic plane.
Waning phases
The phases that come after full moon but before new moon in which less and less visible face of the moon is visible
Stellar parallax
The apparent shift in position of a nearby star (relative to distant objects) that occurs as we view the star from different positions in Earth’s orbit each year
The point directly overhead, which has an altitude of 90° is the ________.
(zenith)
Celestial equator (CE)
The extension of Earth’s equator onto the celestial sphere
Meridian
A half-circle extending from your horizon (altitude 0°) due south, through your zenith, to your horizon due north.
Gibbous phase
The phase of the Moon (or of a planet) in which more than half but less than all of the visible face is illuminated by the sun
Altitude (above horizon)
The angular distance between the horizon and an object in the sky.
Zodiac
The constellations on the celestial sphere through which the ecliptic passes
Circumpolar star
A star that always remains above the horizon for a particular latitude.
Saros cycle
The period over which the basic pattern of eclipses repeats, which is about 18 years 11 1/3 days
Phase (of the Moon or a planet)
The state determined by the portion of the visible face of the Moon or planet that is illuminated by sunlight
When is the next penumbral lunar eclipse that will be able to be seen from Africa.
Just kidding.
And now I messed your score up.
(It’s Sept.16, 2016)
