Exam Topics For Astronomy 107 Lab (Lord I pray to be resourceful for my friends and family)

Always question. Always facts. Always logic.

1A. Binocular FOV

Formula

Angle

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| Define and Calculate

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Size of area of the sky you can see in the eyepiece. Large or small? Larger is easier to find the object. In the area of the sky the moon is 1/2 degree across.

Fact: All eye pieces give their focal length and FOV. That fov is not "True FOV". TFOV is the area you are seeing through the eyepiece. It does matter for what the actual FOV is observable through the eyepiece.

TFOV equation for particular eyepiece for particular telescope. Buy a telescope eyepieces with specifications larger FOV. More expensive, but worth the cost for ease of use.

Formula: TF = fov(eyepiece) / magnification

Question: Why is field of view so important for making observations easy or hard for an observer? FOV will determine how much you can see, so with a small fov you will see less than if you had a large field of view.

Problem Question: Assume eyepiece was 60^degrees for 10 mm eyepiece. And 80^degrees for 20 mm

eyepiece. What is their TFOV for the 2500mm Tele.?

TFOV(10mm) = 60^/-250 = -0.24^

TFOV(20mm)= 80^/-125 = -0.64^

2B. Sun Altitude

How to measure shadow

3C. Moon Phases

Fact: 1/2 MooS is always illuminated by sunlight at all times.

Earth ---------------------> | all black moon phase from earth. Half of the surface is still

illuminated. None of the surface from earth is illuminated.

Question: Moon were in third quarter phase? #5 Yes, half is still illuminated. #6 No, the moon will have different visibility.

Student Q&P #1:

Phase of moon depends on alignment, Moon, Sun, Earth. Plus in all alignments the moon would always get the same amount of sunlight.

Question: If the moon is a full moon tonight will the moon be waxing or waning one week later? Waning. Which side of moon will appear illuminated? Left.

Question: Where to look to see a full moon start rise? That entire night is full. But where to rise? Eastern horizon. At what time? A full moon must be found at 6PM.

Question: Where to look to see sun when full moon rises? Western. Sun is setting in the west.

Fact: If the new moon were visible the, new moon starts to rise at 6AM on the Eastern Horizon.

Acquire full moon rising in evening. Will it be when it starts setting. A full moon.

Acquire: N.M Person. For her it is 12pm(noon). For him opposite it is 12am(midnight). Sunset 6pm, top/half(earth). Sunrise 6am, bottom/half(earth).

At

4D. Speed of stars (arcturus) and of Earth

5E. Lens: The Collector of Light : Gather without worry of right or wrong. Enlightenment.

What do all telescopes do to this day? They gather light. They bring to focus. And they magnify

to provide detail. (Therefore: possibilities). Telescopes main goal is to make outer space as bright

and as large as possible. Its three purposes is to gathering light. Resolution. And magnification.

Purpose of lab is to bring light to a focus and determine that focal length thru the lens equation by

by using convex lenses to magnify images and faithfully find out how individual lens work for

telescopes.

Starlight passes through a lens and merge at a focal point since all light beams from stars are parallel

as they enter a lens. If not parallel it will converge at another different point location.

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| Define and Calculate

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Light Ray: a line perpindicular to the light's wavefronts; its tangent is colinear with the wave vector.

Converging Lens: a lens that causes parallel rays (as of light) to come to a focus.

Focal length: Distance from a converging lens where emerging light rays meet, the focal point F, if the incoming light rays were parallel to the lens.

Magnification: The action or process of magnifying something or being magnified, especially visually. refers to how many times larger the image appears compared to the true size of the object (in this case, 1 cm)

(Equation 1)

Magnification (definition) = Image
Size / Object
Size

M2 = -Hi/Ho

(Equation 2)

Magnification (definition) = Image
Distance / ObjectDistance

-M1 = q/p

Distance of object to lens "P"

Distance from lens to screen image "Q"

M1 and M2 should be close

Percent Difference = |M1-M2| * 100 / [(M1 +M2)/2]

Q: What is percent difference? A way to determine how measurements can differentiate

Thin Lens: In optics, a thin lens is a lens with a thickness that is negligible compared to the radii of curvature of the lens surface.

Object: An object is any source of light: it may be self-luminous (a lamp or a star),or may simply be a source of reflected light (a tree or a planet). Light from an object is refracted(bent) when passed through a lens and comes to a focus to form an image of the original object.

Image:

Inverted Image:

Fact: Does the spot of light become smaller (converging rays of light) or larger (diverging rays)?

Fact: The shorter the focal length, the greater the curvature of lens.

Fact: The focal length is a fundamental property of the lens itself; it does not depend on the location of

the object or image.

Q: How close are the two measurements of magnification. They were % different. It seems unusually large/small differences between measurements.

Q: What does the minus sign mean in the equation for lens magnification? Likely attributed to an inversion of images through one lens. With two lenses there may be not a need to calculate inversions.

Calculation: Find the F(ocal) length of both lenses with lens equation and compare theoretical.

1/p + 1/q = 1/f

% error = [ | F - F' | / F ] * 100

% error means theoretical data and experimental data. It will determine the

difference in results.

Q: Describe what is meant by a main objective lens or mirror? It refracts and focuses light from an object (it bends the light).

Label: Refracting Telescope. Light, Objective Lens, Eyepiece Lens.

Calculation: Find the magnification of a telescope.

focal length of main objective lens (or mirror) / focal length of the eyepiece

M = - f(o)/f(e)

Problem Calculation: Tele. #1 mObjLens with 1500 mm F. What is M w/two eyepieces

w/F 10mm and 20mm? Tele.#2 F = 2500 mm

Lens #1

F(o) = 1500mm

F(e 10mm)M = - 1500/10 = -150

F(e 20mm)M = -1500/20 = -75

Lens#2

F(o)= 2500mm

F(e 10mm)M = -2500/10 = -250

F(e 20mm)M = -2500/20 = -125

Lens #3

F(o) = 2000mm

F(e 50mm)M = -2000/50 = -40

F(e 25mm)M = -2000/25 = -80

Lens #4 (w/o lens formula)

F(o) = 2000m

F(e 12.5mm)M = 100/12.5= 8 ; -20/8 = -2.5

F(e 100mm)M = -2000//100 = -20

Fact: You start with lower magnification to find. Then increase M to study the object more closely.

You change the magnification of one eyepiece to another by a factor of two.

Part II. Ray Tracing

Is there any way to predict where an image will be formed? The answer is “yes” - by noting certain properties of a lens, and then choosing specific rays whose behavior is easy to predict.

6F. Hubble Expansion

7G. Specterometry ( No Calculations )

8H. Speed of Galaxy

Distance of galaxy from us

9I. Magnification

Defn: Focal length

Q: Longer or shorter focal length