What does it mean to accelerate?
To change velocity; to speed up, slow down, or change direction.
What is apparent magnitude
A measure of how bright a star looks in the sky; the larger the number, the dimmer the star appears to us
What is astrology?
The pseudoscience that deals with the supposed influences on human destiny of the configurations and locations in the sky of the Sun, Moon, and planets
What is the celestial equator?
A great circle on the celestial sphere 90° from the celestial poles; where the celestial sphere intersects the plane of Earth’s equator
What are celestial poles?
Points about which the celestial sphere appears to rotate; intersections of the celestial sphere with Earth’s polar axis
What is the celestial sphere?
The apparent sphere of the sky; a sphere of large radius centered on the observer; directions of objects in the sky can be denoted by their position on the celestial sphere
What is the circumpolar zone?
Those portions of the celestial sphere near the celestial poles that are either always above or always below the horizon
What is cosmology?
The study of the organization and evolution of the universe
What is an ecliptic?
The apparent annual path of the Sun on the celestial sphere
What is an epicycle?
The circular orbit of a body in the Ptolemaic system, the center of which revolves about another circle (the deferent)
What does geocentric mean?
Centered around the earth
What does heliocentric mean?
Centered around the sun
What is a parallax?
The apparent displacement of a nearby star that results from the motion of Earth around the Sun
What is precession?
The slow, conical motion of Earth’s axis of rotation caused principally by the gravitational pull of the Moon and Sun on Earth’s equatorial bulge
What is retrograde?
When something appears to be moving backwards or westward.
What is zenith?
The point directly above the observer
What phases of the moon correspond to spring tides
New and full
Does the moon have symmetrical or asymmetrical crust
Asymmetrical, it’s thinner on the near side and thicker on the far side
What causes the moon’s near side to have a thinner crust
It was exposed to the heat from earth’s early formation which kept the near side in a molten state longer than the far side
Why did the moon cool faster than earth
Because it’s 1/4th the size of earth
How fast is mercury spinning
It’s spinning very slow
Does mercury’s axis have a tilt?
No
What causes mercury’s poles to always be cold
It’s axis isn’t titled so the poles never receive sunlight
What is something that the moon and mercury have in common?
They both have thin atmospheres
