Chapter 1 Flashcards
What are three ways you can observe the night sky?
Binoculars, Telescopes, and Eyes
Is there a difference in the sky depending on whether you live in the Southern or Northern Hemisphere?
Yes, star charts vary
Is there a difference in the sky depending on the season?
Yes
Is there a difference in the sky depending on the season?
Yes
What are the two largest celestial objects we can view?
Sun and Moon
Why is there a trend of east-to-west motion when observing the sun, the moon, and the stars?
This is because of the earth’s rotation on its axis; because the earth is spinning in the opposite direction.
What is this trend of the earth’s rotation called?
Diurnal Motion
What is the approximate rotation time of the earth that relates to other objects in the sky as well?
Approximate 24-hour cycle
Name the concept that is useful for understanding the positions and motions of stars
Celestial sphere
Name the concept that involves expanding the earth’s equator into space
Celestial equator
What are the constellations called that are close enough to the celestial pole that they are visible all night, all year round?
Circumpolar constellations
Since the 23 hours and 56 minutes period is the length of time it takes the earth to turn as seen from a distant star, this is called?
Sidereal day
Describe the difference between the sidereal day and the solar day
The sidereal day is the true rotation rate of the earth as seen from a distant star. The solar day is how long it takes for the sun to return to its highest point in the sky as viewed from the location on earth
Since stars rise two hours earlier every month, they rise how many hours earlier after six months?
12 hours
Since stars rise two hours earlier every month, they rise how many hours earlier after six months?
12 hours
Why is it difficult to observe planets, globular clusters, and nebulae when the moon is full?
It washes out nearly everything else in the sky
The moon rises (on average) about _________ later each day?
50 minutes
Why is it ironic that the moon is called “the moon” in regard to the gravitational pull of the earth and sun?
The gravitational pull of the sun on the moon is about twice the pull of the earth on the moon
The phases of the moon are not related to the earth’s shadow, but to the ________ of the day side of the moon we can see from our position.
Percentage
It takes ______ days for the moon to go through its phases, and _____ days for its orbital period.
29.3, 27.5
The motion of the planets is complicated because their apparent motion in the sky is the combination of their _______ around the sun, plus the _____________ in position due to Earth’s motion around the sun.
True motion, apparent shift
What is responsible for the seasons on the earth?
The earth’s rotation axis that is tilted relative to its orbit around the sun by 23.4 degrees
Describe what the two coordinate systems widely used in astronomy are based on.
The first is based on our local horizon. The second is based on the celestial sphere.
________ describes how high above the horizon an object is (in angle).
Altitude
_________ describes how far along the horizon an object is to the right of due north.
Azimuth
Equatorial coordinates are based on the ______________. In particular, they are based on the celestial _________.
Celesital sphere, equator
Stars with a declination that is less than your latitude will pass ________ of zenith when they cross the meridian, and stars with a greater declination will pass ________ of zenith.
South, North
Which RA coordinates can be seen depends on the time of _____ and the time of _____.
Day, Year
Once calibrated on an object whose RA and Dec you know, you can use ________ circles on a telescope to find any other RA or Dec.
Setting
What is the best way to get a feel for the motions in the sky?
It’s best to get outside and watch.
A star wheel or planisphere helps you find stars by lining up the ______ with the ______ on the planisphere.
Date, Time
A planisphere helps find constellations, but will not help with ____ or ____.
Planets, Moon
