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Astronomy 110 > Chapters 5 & 10 > Flashcards

Chapters 5 & 10 Flashcards

1
Q

What is a lens?

A

A lens is a circular glass disk that bends and focuses light.

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2
Q

What is a convex lens?

A

Thicker at the middle. Parallel beams of light pass through the lens and the refracted rays converge at one point called the focus.

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3
Q

What is a concave lens?

A

Thinner at the middle. Parallel beams of light pass through the lens and the refracted rays converge at one point called the focus.

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4
Q

What is focus?

A

The point at which rays of light that were initially parallel (such as light from a distant star) converge.

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5
Q

What is focal length of a lens or mirror?

A

The distance from the surface of a lens or mirror to its focal point. Also called focal distance, focus.

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6
Q

What is refraction of light? Why is this phenomenon related to the telescope?

A

Refraction is a bending of light. Refraction is used to bend light through two lenses to magnify celestial objects in the far distance.

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7
Q

What are the two main types of telescopes?

A

Reflector and Refractor

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8
Q

What are the advantages/disadvantages of REFLECTOR telescopes?

A

Advantages: The use of mirrors allows the telescope to be much smaller in size compared to refractor telescopes.
Disadvantages: The small secondary mirror blocks some of the light coming into the telescope.

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9
Q

What are the advantages/disadvantages of REFRACTOR telescopes?

A

Advantages: Less expensive than reflector telescopes.
Disadvantages: More powerful refractor telescopes are often more bulky.

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10
Q

What is a reflector telescope?

A

A telescope that uses mirror to focus light to a focal point. Uses two concave mirrors and a secondary mirror which reflects light entering into the telescope.

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11
Q

What is a refractor telescope?

A

A telescope that uses convex lenses to focus light. Uses a large lens and a smaller lens.

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12
Q

What is the magnification of a telescope and how is it determined?

A

Magnification of a telescope is how much larger we can see an object. We find magnification by dividing the focal length of the primary lens or mirror by the focal length of the eye piece.

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13
Q

What is meant by Power of a telescope? How do astronomers determine power of a telescope?

A

The power of a telescope is how much light that the telescope is able to collect. We find power by the Area Equation pi x r^2. The larger the area the more powerful.

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14
Q

Explain how astronomers use radio telescopes to study the heavens.

A

Radio telescopes are used to observe radio waves, not necessarily visible light rays.

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15
Q

What is adaptive optics?

A

A technique in which a telescope mirror flex rapidly to compensate for the bending of star light caused by atmospheric turbulence.

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16
Q

What are the basic properties of the sun?

A

The sun is made of 74% hydrogren, 25% helium, and 1% other elements.
Radius of the sun: 696,000 km
Temperature of the sun: Surface - 5,800 K
Core - 15 million degrees
Luminosity: 3.86x10^26 watts

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17
Q

Rotation of the Sun

A

The sun rotates on its axis. It takes 27 days for the Sun to complete 1 rotation at the equator, 33 days at the poles and on average 30 days for the entire sun.

18
Q

Revolution of the Sun

A

At the speed of 790,000 km/h the Sun takes 220 million years to revolve around the galaxy once.

19
Q

Why does gas not dissipate into space?

A

The mass of the Sun is so large that the Sun’s gravity is able to withhold the immense amount of pressure exerting from it’s core.

20
Q

What are the 6 layers of the Sun?

A

1) Corona
2) Chromosphere
3) Photosphere
4) Convection Zone
5) Radiative Zone
6) Core

21
Q

What is the Corona?

A

Gaseous substance floating around the sun that’s 2 million degrees/1 million K hot. X-rays are emitted from this region.

22
Q

What is the chromosphere?

A

Surface of the sun which has streams of gas protruding from it’s surface (pinkish color). UV is emitted from this region. 10,000 K

23
Q

What is the photosphere?

A

Surface of the Sun that we can see. 5,800 K

24
Q

What is the Convection Zone?

A

A region where heat energy is transferred from the core to the surface, helping to help temperature down somewhat. 2 million K to 5800K

25
Q

What is the Radiative Zone?

A

A region of the interior where energy is transported by radiative diffusion. 7 million to about 2 million K

26
Q

What is the core?

A

The central region of a star where there is an intense force of gravity and where nuclear fusion can occur because of such high temperatures. 15 million degrees K.

27
Q

What is nuclear fission?

A

When a nucleus splits into smaller pieces/elements.

28
Q

What is nuclear fusion?

A

When small nuclei stick together to make a bigger one. In the sun, 4 helium atoms come together to make helium and energy.

29
Q

What is the proton-proton chain?

A

1) 2 H protons collide
2) Makes a He nucleus and 1 H proto
3) Another H proton collides with it and gives off a gamma ray
4) The new H gets stuck and now there is a pair of one He nucleus and 2 H protons hanging on.
5) The pair collides with each other, knocks off two protons emitting energy
6) Hydrogen is fused into Helium

30
Q

What is the evidence of solar convection on the Sun?

A

Granule like features on the sun that is actually a result of the convection of heat from the inner layers to the Sun’s surface.

31
Q

What are some activity that we observe on the Sun?

A

Sunspots, solar flares, solar prominence, solar eruptions, and solar wind.

32
Q

What is a solar flare?

A

When magnetic activity sends bursts of X-rays and charged particles into space.

33
Q

What are sunspots?

A

Cooler-than-other places on the sun that are regions with very strong magnetic fields often larger than the Earth itself.

34
Q

What do scientists mean by continuous spectrum?

A

We can’t tell where the colors start or begin.

Wavelengths are constantly changing.

35
Q

How can we figure out the number of electrons in each shell?

A

Number of electrons = 2n^2

36
Q

What is the ground state of an atom?

A

The lowest most orbit where electrons are the most comfortable in the atom.

37
Q

What happens when an electron is heated?

A

Light is produced/emitted.

38
Q

What does excitation (of electrons) mean?

A

When an electron jumps to a higher orbit than the ground state.

39
Q

What is de-excitation (of electrons)?

A

When an electron jumps down to a lower orbit after it jumps to a higher orbit.

40
Q

What is the function of a dark line spectrum/absorption kine spectrum?

A

Absorbing certain radiation while sunlight is passing through a cloud.

41
Q

What is the function of a bright line/emission line spectrum?

A

To measure the elements of light passing through another object.

Astronomy 110 (3 decks)

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