astronomy pretest?

Question

a-degree angle formed when viewing distant objects from diff. points of view
b-top of the celestial sphere directly above a viewer
c-degree angle around the horizon from a point of reference
d-degree angle above the horizon
e-"wandering" of a plantet against the celestial sphere
1. What definition best fits azumith
2.What definition best fits declination

a.meters
b.kilometers
c.astronomical units
d.solar days
e.light years
3.Which unit of measure can best be used to estimate the distance to the planets
4.stars?
5.between galaxies?

6.Which tool can be used to show that the earth rotates on its axis? a-clock, b-meter stick, c-pendulum, d-telescope, e-laser
7. which math subjects were most helpful to ancient scientists in estimating size of sun&distances to celestial objects?a-algebra,b-geometry,c... theory
8.Whats a lunar eclipse?Solar eclipse?
9.whats a "new moon"? "last quarter moon"? "waning crescent moon"?"first quarter moon?

thx for answering.

Answer 1

1. d
2. c
In the other options listed:
a - parallax
b - zenith
e - prograde (moving in the same direction as other objects in the system) and retrograde (moving in the opposite direction

3. C
4. E
5. E
6. Pendulum
7. Geometry
8. Lunar eclipse: when the earth casts a shadow on the moon
Solar eclipse: when the moon gets directly between the earth and the sun and casts a shadow on the earth
9. New moon - the moon is between the sun and the earth and the side facing earth is in shadow
Last quarter - when the moon makes a right triangle with the earth and sun and we see only half of the sunlit side (the moon is past full)
Waning crescent - when the moon has moved just enough past new moon to show a tiny lit crescent
First quarter when the moon makes a right triangle with the earth and sun between new moon and full moon

Answer 2

1 answer is C
2 answer is D
3 answer is C
4 answer is E
5 answer is still E but it should be "parsecs" or "mega parsecs"

6 all of the above. but im guessing your teacher is thinking telescope. or clock. but probably telescope.

7 answer is B geometry
8 lunar eclipse is when the earth is directly between the sun and moon, leaving the moon in earths shadow. a solar eclipse is when the moon is between the sun and earth and the moon blocks out the light of the sun.

9 new moon is when the moon is near the line of sight of the sun. last quarter is when the moon is half full but heading towards new phase. waning cresent, is the phase right after new. first quarter is the half moon heading towards a full moon.

Answer 3

I'll do it in reverse.

a. When viewing objects from a different point of view, the angle may appear different. The closer the object, the greater the angle. The angle is called parallax and can be used to estimate distance.

b. The point directly above the observer is called the zenith. The horizon, in astronomy, is defined as the circle that is exactly 90 degrees from the zenith (your real horizon may be different because of mountains or because of your height).

c. The direction you face when you are looking at a star (or planet or whatever) is called the azimuth. Nowadays, it is measured along the horizon, in degrees towards the right, starting from North (000 = N, 090 = E, 180 = S, 270 = W, 315 = NW etc.)
It used to be measured from from the meridian (N or S) in either direction so as to always be less than 90 degrees,
as in N53E (=053), N20W (=340), S35E (=145), S17W (=197).

d. The vertical angle from the horizon to an object is the altitude of an object. It is sometimes called height (but rarely). The altitude of something at the zenith is exactly 90 degrees. The altitude of a body that is rising or setting is 0 degrees. When a body is below the horizon, the altitude is negative. This can happen if you are located very high (remember that your real horizon may be lower than the astronomical horizon).

e. I do not know what the 'wandering' of a planet is. In fact, the word 'planet' comes from an ancient Greek phrase (aster planetes) meaning wandering star. Therefore, a planet IS wandering.


1. What definition best fits azimuth? c
2. What definition best fits declination? none of the above.
The celestial sphere has a special point called the pole (the point around which the sphere appears to rotate). At 90 degrees from the pole is the celestial equator. Declination is the number of degrees that a body is from the equator. If a body is 40 degrees from the equator and in the northern hemisphere, then we say its declination is 40 degrees North. The latitude of the observer is defined from the declination that passes at the zenith. So, if a star with a declination of 40 N passes directly through your zenith, then your latitude is 40 N.

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a. meter (about the length of my arm) is defined by the distance that light travels in 1 / 299,792,458 of a second. It used to be defined as 1/10,000,000 of the distance from the equator to the pole, along the meridian going through Paris.

b. a kilometer is 1000 metres.

c. astronomical unit: the mean distance between Earth and the Sun (it is now defined a bit differently but, basically, that is what it means).

d. A solar day is the time it takes for one rotation of Earth in relation to the Sun (e.g., from noon to noon). The mean solar day is 24 hours.

e. light year: the distance that light travels in a Gregorian year (365.2425 days of 86,400 seconds)

3. Distances to planets are best estimated in astronomical units. There are formulas one can use, such as Kepler's law. One law says that the orbital period of a planet (P) and its distance from the Sun (R) are related by this proportion:
P^2 = R^3.
If you decide to use 'Earth years' to measure the period P and 'astronomical units' to measure the orbital radius R, then it becomes easy. For Earth (P = 1 year, R = 1 astronomical unit), 1^2 = 1^3 (1 squared = 1 cubed).

It was (and still is) easy to determine the orbital period of a planet. For example, Jupiter's period is 11.86 years.
Using P^2 = R^3 we have
(11.86)^2 = 140.86 = R^3
Therefore R = cube root of 140.86 = 5.2 astronomical units.
That is how astronomers knew the relative distances to planets even before the invention of the telescope.

4. Many tables give the distances to stars in light-years. Of the choices given above, that is the best.

However, for many calculations involving stars, we use a unit called a 'parsec'. It is directly determined by measuring the parallax angle of a star seen over a baseline of 1 astronomical unit. Many values involving a star's brilliance or the density of matter in a volume of space, are given for round figures in parsecs.

5. Between Galaxies? same thing. The distance to the Andromeda Galaxy is approximately 2,400,000 light years (approximately 736,000 parsecs). If we tried to measure such a distance in metres, kilometers or even astronomical units, the numbers would be too big:
22,700,000,000,000,000,000,000 metres,
22,700,000,000,000,000,000 kilometres,
151,800,000,000 astronomical units.

The Andromeda Galaxy is in our 'Local Group' (it is one of our neighbours). Most other galaxies are so far that we measure the distances in 'Megaparsecs (millions of parsecs).

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6. There is a giant pendulum hung under the central cupola of the Pantheon in Paris. Wiki shows how it was used to prove Earth's rotation:
http://en.wikipedia.org/wiki/Foucault_pendulum
A telescope was used in 1725 to prove that earth moves in an orbit around the Sun (http://en.wikipedia.org/wiki/Aberration_of_light), that is 'translation', not rotation.
but the Pendulum was, in 1851, "the first dynamical proof of the rotation in an easy-to-see experiment". Earlier proofs included the deflection of winds moving from High to Low pressure centres (Coriolis effect -- 1835)

7. Which math subjects? they are all useful. However, the 'ancient' scientist (e.g., Greeks) used geometry to solve most problems. Although they did find many answers, they did struggle very long with models involving circles, and circles within circles, thinking that the heavens can only work with the 'perfect' geometric shape: the circle.

(algebra was later invented by the Arabs)

Kepler used geometry and trigonometry to propose that maybe the orbits were ellipses instead of circles; his work was based on the observations of Tycho Brahe who used techniques that, today, we would say were like 'statistical analysis'.

Galileo used trigonometry and 'optimization' (part of numerical analysis) to determine in 1611 the orbits of Jupiter's moons (that he had just discovered in 1610).

Newton invented calculus to prove that Kepler and Galileo were correct and to support his laws of motion (including gravity).

8. An eclipse is a disappearance. For example, you can be stuck at a meeting, the meeting is boring, so you 'eclipse' yourself (you disappear to go somewhere else, less boring)

A lunar eclipse is when the Moon enters Earth's shadow. Often, the Moon gets a lot darker but it does not disappear completely because some red light from the Sun does get refracted by our atmosphere, and the eclipsed Moon look very red (and dark).

A solar eclips is when the Moon gets between the Sun and us, blocking the Sun from view. The Sun disappears for a few seconds (or a few minutes).

9. http://en.wikipedia.org/wiki/Moon_phases

New Moon is when the Moon is in the same direction as the Sun. If it is exactly between us and the Sun, it is a solar eclipse. However, it usually 'misses' the Sun (its line passes just above or just below the Sun) and solar eclipses are rare. It is called 'New' because that position (or the first sighting of the Moon a day or two after New Moon) marks the start of a new lunar month in places where lunar calendars are still used (e.g., arab countries, China, India, Siam, Israel...). The New Moon is not visible because the part of the Moon that gets light from the Sun is facing away from us.

The First Quarter is when the Moon has gone one quarter of its orbit (approximately one week after New Moon). That is why we call it a quarter, even though the Moon looks half-full.

Full Moon is the opposite of New Moon. The entire face of the Moon is lit.

Last Quarter is when the Moon is at the third quarter of its orbit (the 'last' quarter before the next New Moon).

Waxing means increasing in size.
Waning means decreasing in size.

Crescent is when the Moon is narrow. Waxing crescent is when you see it in the West right after sunset (the next day, it will look a bit fatter and higher). Waning crescent is when you see it in the East just before sunrise.

Answer 4

obvious fee is how bright an merchandise looks in the sky. If i undergo in innovations properly, the decrease the quantity, the brighter the object seems to be. So without actual answering the question, i will permit you understand which you will desire to calculate the style between the two magnitudes and convey that as a ratio or ingredient. Take 0.8-a million.2 to get the style in brightness between those 2 cases. And if it facilitates something, Mars have been given fainter.