Unit E Section 1.5 Flashcards
To locate the position of an object in space, two questions must be answered:
- “How high in the sky is it”?
- “In which direction”?
what is the first measurement for tracking things in the sky?
compass direction called the azimuth
Different measurements for Azimuth for different directions?
north as 0° and going clockwise, the azimuth will tell you which direction to point
180° from 0° would have you pointing due south
270° would have you pointing west
What is the second measurement?
shows how high the object is in the sky.
altitude
Where does altitude range from?
The altitude ranges from 0 at the horizon to 90° straight up.
What is Zenith?
Zenith refers to the highest point directly overhead.
How is the motion of stars seen from Earth?
- Because they are at such enormous distances from Earth, the stars appear to stay in one place in the sky
- Only when viewed over extremely long periods of time can some stars be seen to move very slightly
How is planetary motion seen from Earth?
a person needs to wait only a few days or weeks to see a planet change its position against the background of stars
Sometimes the planets seemed to speed up over time in their movements across the sky.
Other times they appeared to standstill
What word does the word planet come from?
“Planet” comes from the ancient Greek word for
“wanderer.”
What is ecliptic?
a great circle on the celestial sphere representing the sun’s apparent path during the year, so-called because lunar and solar eclipses can occur only when the moon crosses it.
What is a celestial sphere?
The celestial sphere is the name given to the very large imaginary “sphere of the sky” surrounding Earth
What is a celestial equator?
The celestial equator is the imaginary line around that sphere of sky directly above Earth’s equator
What position of the Earth makes the solstice and equinox occur?
The ecliptic—the apparent path of the Sun through the sky during the year—crosses the celestial equator at the vernal (spring) and autumnal (fall) equinoxes.
The Sun’s most northerly position on the ecliptic marks the summer solstice. Its most southerly position marks the winter solstice.