Quiz 3 Practice Flashcards
refractor
combination of lenses
reflector
mirrors instead of lenses
angular size
how much of the sky the object takes up
angular resolution
a measure of how well a telescope can make out small details
“seeing”
wiggles (turbulence) in the atmosphere that limit angular resolution
zenith
observer-based coordinate; the point directly above your head that meets the top of the celestial sphere
North Star/Polaris
found at the location of the North celestial pole; Polaris is our current North Star
celestial sphere
an imaginary sphere extending all around Earth
celestial equator
an imaginary equator that extends to the sides of the celestial sphere
celestial poles
two celestial poles; the north celestial pole and the south celestial pole
altitude
“height” of an object above the observer’s horizon; begins at 0° at the horizon, rises to 90° at the zenith
azimuth
angular distance around your horizon; begins at 0° facing due North, extends full 360° NESW around observer’s horizon
circumpolar star
stars that never set below the observer’s horizon
circumpolar zone
the circumpolar region; a circle with a radius equal to the observer’s latitude
equinox
when the ecliptic passes through the celestial equator; causes the Spring and Autumn equinoxes
How does apparent motion differ from true motion?
Apparent motion is caused by the Earth’s rotation; objects appear to move because the Earth is moving past them as they rotate. Stars have true motion but it is difficult to measure (can take decades).
What are the two main goals of a telescope, and how do we achieve them?
1.) Maximize light (create bigger diameters)
2.) Maximum resolution (a. use mirrors over lenses; b. use multiple telescopes to make one image; c. use a laser to make a fake star and un-wiggling formula)
Why are reflectors preferred over refractors?
Refractors are made of lenses that can only be supported on the sides; Can cause distortion of images if the lens is too large and can be very heavy. Reflectors do not mend like lenses and are significantly lighter, you can also add multiple mirrors together to make a bigger mirror
Why do we need to send some telescopes to space?
(1) Get above the atmosphere for good seeing
What is a false color image and why do we make them?
when we assign colors to wavelengths that aren’t their true wavelengths; helps with measuring depth, different stars, objects, galaxies, and the path of light in space
How can we locate Polaris in the night sky?
1.) Look due north, at 0° azimuth
2.) Look up from the horizon to an altitude equal to your latitude on Earth
Why does the Sun appear to travel along the ecliptic?
The Sun appears to travel along the ecliptic because the Earth passes the sun each day as it turns on its axis
Why aren’t the ecliptic and celestial equator the same?
Ecliptic is the apparent path circular path of the Sun over the course of one year. The celestial equator is an imagined equator of the Earth. Touch twice (equinoxes); at furthest part 23.5° twice a year (solstices)
angular resolution formula
θ = (70°)(λ / d)
astronomy degrees
astronomers measure how far apart objects appear in the sky by using angles
