Why is it called the angle of right ascension?
It is the distance eastward which refers to the right. So it is referring to the rising to a higher level eastward (right).
There are 2 basic types of telescopes. What are they? Is there a 3rd? What does it do?
1. Refractive
2. Reflective
3. Optical--they use refraction and reflection.
Where is the horizon?
a. directly overhead
b. along the celestial equator
c. the boundary between land and sky
d. along the path that the Sun follows throughout the day
e. the line running from due north, directly overhead, ending due south.
c. the boundary between the Earth and the sky.
How many constellations are there?
The celestial sky is divided into 88 unequal areas, each one containing a constellation.
Which of the following lies on the celestial sphere directly over Earth's equator?
a. ecliptic
b. celestial equator
c. north celestial pole
d. south celestial pole
e. horizon
c. north celestial pole
The length of time it takes Earth to orbit the Sun is...?
a year
What is another name for the Sun's annual path?
The ecliptic.
How are constellations useful to astronomers?
The stars are fixed on the celestial sphere just like cities are on a map. Therefore, they do not change in relation to one another, so when describing a celestial anomaly, one can describe its placement in relation to the constellations.
What is the celestial sphere, and why is this ancient concept still useful today?
The celestial sphere is a map of the earth, showing the equator, line of right ascension and declination, north and south poles, elliptical, and the vernal equinox. It is still used today to map out the constellations and measure distances and sizes betwe
What is the celestial equator, and how is it related to Earth's equator? How are the north and south celestial poles related to Earth's axis of rotation?
If we expand Earth's equator onto the celestial sphere, we obtain the celestial equator, which divides the sky into northern and southern hemispheres. We can also project the north and south poles into outer space along Earth's axis of rotation. Doing so
What is the ecliptic, and why is it tilted with respect to the celestial equator?
The ecliptic is the Sun's annual path around the celestial sphere. The ecliptic and the celestial equator are different circles tilted 23.5? with respect to each other on the celestial sphere. This occurs because Earth's rotation axis is tilted 23.5� away
By about how many degrees does the Sun move along the ecliptic each day?
Because there are about 365.25 days in a year and 360� in a circle, the Sun appears to move along the ecliptic at a rate of slightly less than 1� per day.
Through how many constellations does the Sun move every day?
Less than 1...
Through how many constellations does the Sun move every year?
13 constellations, called the Zodiac.
Why does the tilt of Earth's axis relative to its orbit cause the seasons as Earth revolves around the Sun?
For people living in the Northern Hemisphere: When the sun, on its ecliptic, crosses the Northern Hemisphere, people living in the Northern Hemisphere will start to experience more sunlight as the sun will rise earlier and set later in the sky. This occur
What are the vernal and autumnal equinoxes? What are the summer and winter solstices? How are these four points related to the ecliptic and the celestial equator?
The winter solstice is the point on the ecliptic farthest south of the celestial equator. It is also the day when the Sun rises to the lowest height at noon and it signals the day of the year in the northern hemisphere that has the fewest number of daylig
How does the daily path of the Sun across the sky change with the seasons?
In wintertime, starting with the winter solstice, the sun doesn't get very high, it rises farthest south of east, and there's the least amount of sunlight during the day. On the vernal equinox, and during spring, the sun rises precisely in the east and se
Why is it warmer in the summer than in the winter?
During the days with longer periods of daylight, more light and heat from the Sun strike that hemisphere. So, when the Sun is higher in the sky, its energy is more concentrated on Earth's surface. Thus, during these days more energy is deposited on each s
Why is it convenient to divide Earth into time zones?
Before time zones, local time was based on astronomical noon. Because the Earth is rotating eastward, the Sun is highest at different longitudes at different times, so there would be differences in times, which would get confusing, if someone wanted to tr
Why does the Moon exhibit phases?
The moon moves from west to east, while the earth moves from east to west. Its position among the background stars changes, as well as its position relative to the moon. The sun illuminates half the moon at all times. The moon's phase that we see depends
What is the difference between a sidereal month and a synodic month? Which is longer? Why?
The sidereal month is the time it takes the Moon to complete one revolution with respect to the background stars. However, because Earth is constantly moving in its orbit about the Sun, the Moon must travel through more than 360� to get from one new Moon
What is the difference between the umbra and penumbra of a shadow?
The umbra is the part where it's completely black nothing can be seen, the penumbra is the part where Earth blocks only some of the sunlight.
What is a penumbral eclipse of the Moon? Why is it easy to overlook such an eclipse?
A penumbral eclipse is when the Moon passes through only Earth's penumbra. It is easy to miss because the moon still looks full, just a little dimmer than usual and sometimes slightly reddish in color.
Which type of eclipse--lunar or solar--have most people seen? Why?
Lunar, because they occur more regularly.
How is an annular eclipse of the Sun different from a total eclipse of the Sun? What causes this difference?
The moon completely covers the sun in a total eclipse, whereas in an annular eclipse a ring of sunlight can be seen around the moon.
At which phase(s) of the Moon does a solar eclipse occur? A lunar eclipse?
Solar-new moon. Lunar-full moon. They have to happen on the ecliptic.
Is it safe to watch a solar eclipse without eye protection? A lunar eclipse?
No. A lunar eclipse--yes.
Do the planets orbit the sun at constant speeds?
NO. The closer a planet is to the sun in its elliptical orbit, the faster it is moving. The planet moves fastest at its perihelion and slowest at aphelion.
Do all the planets orbit the Sun at the same speed?
No. A planet's speed depends on its average distance from the sun. The closest planet moves fastest, the most distant planet moves the slowest.
How long as the Earth existed, and how do we know this?
Earth formed along with the rest of the solar system about 4.6 billion years ago. The age is determined from the amount of radioactive decay that has occurred on Earth.
What typical shape(s) do moons have, and why?
Although some moons are spherical, most look roughly like potatoes. Those that are spherical are held together by the force of gravity, pulling down high regions. those that are potato-shaped are held together by the electromagnetic interaction between at
Who wrote down the equation for the law of gravitation?
a. Copernicus
b. Brahe
c. Newton
d. Galileo
e. Kepler
c. Newton
Which planets can never be seen at opposition? Which planets never pass through inferior conjunction?
(Mercury & Venus). Superior and inferior planets.
What are the synodic and sidereal periods of planets?
The sidereal periods are the true orbital periods. They are measured with reference to the position of a planet or other body compared to background stars. The synodic periods express the time taken to cycle through configurations, such as superior to sup
What are adaptive optics?
Adaptive optics refers to the reshaping of a telescope mirror based on the amount of twinkling caused by atmospheric turbulence. Adaptive optics reduces the problem of atmospheric distortion, thereby increasing the resolution that the telescope can delive