Solar System Astronomy Chapter 5 + 6

Choose all of the effects that would automatically happen if the wavelength of light were increased.

The frequency of the light would decrease. The energy of the light would decrease.

Neutrinos pass straight through solid matter, making them difficult to detect. Luckily, they do react with one type of force—the nuclear weak force. For instance, on extremely rare occasions, a neutrino may interact via the nuclear weak force with a chlorine atom, turning it into a radioactive argon isotope. However, this is rare enough that we would almost never witness this type of reaction in the natural world. Which of these actions would improve our chances of seeing this reaction and thus detecting the presence of a solar neutrino?

- Build a detector made of a large amount of chlorine. - Go to a place where there are a lot of solar neutrinos.

The Sun's interior is extremely dense, so as soon as a photon is produced inside the Sun, it is almost instantly absorbed by matter. It is then emitted in a random direction and possibly at a different wavelength, only to be absorbed again and reemitted. This results in a random walk of the photons as they move toward the surface, where they can escape into space. This situation may sound familiar: it is the effect of a blackbody, which is similar to the simplified view of light bouncing around in a box until it is able to randomly escape from a tiny hole, as shown in the figure. Say you are trying to study the nuclear reactions in the Sun's core by observing photons coming off its surface. How will this random walk affect your results?

- Each photon would have been created a long time ago: it would be impossible to use them to study nuclear reactions as they are happening right now in the Sun's interior. -Each photon may be a different energy than it was when it was created in the nuclear reactions. - Each photon may be a different color than it was when it was created in the nuclear reactions.

Rank the types of radiation in order of their energy, from least to greatest.

1) Radio Waves 2) Infrared 3) Red Visible Light 4) Blue Visible Light 5) X-rays 6) Gamma Rays

Rank each of the following colors by how much each refracts, from most (at top) to least (at bottom).

1. Bue 2. Green 3. Red

Place the following regions of the Sun in order of increasing radius.

1. Core 2. Radiative Zone 3. Convective Zone 4. Photosphere 5. Chromosphere 6. Corona

The first neutrino detector (Homestake, shown in this image) consisted of a 100,000 gallon tank of a chlorine-containing liquid, built 1,500 meters underground to block out particles other than neutrinos that might affect the results. Calculations from the model of the nuclear reactions expected to occur in the Sun predicted that it would detect about 1 neutrino every day as it turned a chlorine atom into argon. In actuality, only 1 neutrino was detected about every 3 days. This was referred to as the solar neutrino problem. What might this problem imply?

- There were fewer neutrinos detected than expected, so something might be wrong with our models. - The detector may have been missing some neutrinos for some reason.

High-speed computers have become critical tools for astronomers. Which of the following require the use of a high-speed computer?

- analyzing images taken with very large CCDs - generating and testing theoretical models - studying the evolution of astronomical objects or systems over time

Improved resolution is helpful to astronomers because it enables them to view

- many objects close together - very distant objects - small features of an object

Choose all that apply. CCD cameras are better astronomical detectors than the human eye because

- their quantum efficiency is higher. - the integration time can be longer. - they can observe at wavelengths beyond the visible

All large astronomical telescopes are reflectors because

- they can be shorter - chromatic aberration is minimized - they are not as heavy

The two Keck 10-meter telescopes, separated by a distance of 85 meters, can operate as an optical interferometer. What is the Keck interferometer's resolution when it observes in the infrared at a wavelength of 2 microns?

0.005 arcsec

Building effective detectors for particles or waves that scientists would like to study is a real challenge. Some are easily detected, while others are not. Rank the following items in order of increasing difficulty of detection.

1. Infrared photons 2. Neutrinos 3. Gravity waves

Label the layers of the Sun as represented in this graph of density and height above the solar surface.

1. Photosphere 2. Chromosphere 3. Corona

The diameter of the full Moon's image in the focal plane of an average amateur's telescope (focal length = 1.5 m) is 13.8 mm. How big would the Moon's image be in the focal plane of a very large astronomical telescope (focal length = 250 m)?

2300.5

Suppose an atom has three energy levels, specified in arbitrary units as 10, 7, and 5.In these units, which of the following energies might an emitted photon have?

3, 2, 5

The light-gathering power of a 4-meter telescope is __________ than that of a 2-meter telescope.

4 times larger

In the video, what does the paper ball represent?

A photon

Given this, what would observer 2 (who does not see the star through the gas) observe in the spectrum of the cloud of gas in the picture above? Select the appropriate spectrum below.

An all black diagram with a single bright line somewhere.

The resolution of radio telescopes suffers greatly from the large wavelengths of the light they are observing. What can be done to a radio telescope to improve its angular resolution?

Make its dish bigger

Which of the following can astronomers determine directly from the spectrum of an object?

Composition Temperature Speed toward or away from an observer

The Sun's atmosphere produces different types of spectra depending on the conditions of the layer. This graph shows how the temperature changes at different heights above the Sun's surface. Match the types of spectra to the layer in which they are produced.

Continuous, Absorption, Emission, X-ray emission

Four transitions are shown in the image. Order the transitions in the order of increasing energy.

D, C, B, A

How does the spectrum of a distant star reveal the star's chemical composition?

Dark lines, also called absorption lines, within the spectra are "fingerprints" for the different atoms and molecules within a star's atmosphere.

Imagine that you get the image focused just right, so it is crisp and sharp. The next person to use the telescope wears glasses and insists that the image is blurry. But when you look through the telescope again, the image is still crisp. Explain why your experiences differ.

Everyone's eyes have slightly different focal lengths.

The mass of hydrogen is 1.6726 x 10-27 kg, and the mass of helium is 6.6465 x 10-27 kg. Given this, which of the following nuclear reactions would result in a decrease of total mass, and thus a release of energy, while keeping the same number of particles involved?

Four hydrogen nuclei combine into one helium nucleus.

The image provided shows a light source moving relative to three different observers: Fred, Velma, and Daphne. If the light source is emitting green light and moving with sufficient speed, identify which colors each person could possibly see.

Fred - Red Light Velma - Blue Light Daphne - Green Light

In a vacuum, light travels 300,000 km every second. Examine the following figure, which shows how long it takes for light to travel particular distances, and then scroll down to the question at the end. Based on the time frames given in the above figure, which of the following are implications of the finite speed of light?

If the light of the Sun were suddenly extinguished, we wouldn't notice it from Earth for over 8 minutes. There would be a noticeable delay in communications at the speed of light between Earth and astronauts on the Moon. When we gaze at the Andromeda Galaxy, we are looking back in time to the way it used to appear millions of years ago.

Sort the particles into the categories describing whether they are input particles that get used up in the reaction, new output particles persisting after the reaction, or intermediate particles that exist only temporarily during the reaction.

Input: Hydrogen, Electron Output: Neutrino, Gamma Ray, Helium-4 Intermediate: Deuterium, Helium-3, Positron

Match the following properties of telescopes with their corresponding definitions.

Interferometer - Several telescopes connected to act as one Focal Length - Distance from lens to focal plane Aperture - Diameter Resolution - Ability to distinguish objects that appear close together in the sky Chromatic Aberration - Rainbow-making effect Diffraction - Smearing effect due to sharp edge

If the energy leaving the planet is restricted, what happens to the temperature of the planet?

It increases

What is a neutrino?

It is an almost massless, neutral particle that is produced in nuclear processes.

If the integration time is long enough to collect the light from this entire animation, what effect would seeing have on the image of the object?

It would blur the light from the object, effectively increasing the angular resolution of the telescope (making the angular resolution better).

Imagine decreasing the size of the lens in the figure above. Which choice below best describes what would happen?

Less total light from the source will hit the lens, making it appear fainter on the detector.

In the Sun, four hydrogen nuclei do not fuse directly into a helium nucleus. The overall reaction involves several steps, and other particles are also produced in the process. Study the AstroTour about The Solar Core. Then select all the particles/elements that are created by the reaction.

Neutrino, Gamma Ray, Positron, Helium

Why do photons take so much longer than neutrinos to emerge from the Sun?

Photons interact strongly with matter, while neutrinos do not.

Besides adding adaptive optics to a telescope, what else can be done to reduce the effects of seeing?

Put the telescope at a higher altitude (the height above sea level).

Which of the following can be observed from Earth's surface?

Radio Waves Visible Light

Identify the statement that best describes how the latitude of sunspots varies over a sunspot cycle, which is defined to begin at solar minimum.

Sunspots are at higher latitudes at the beginning of a cycle, and lower latitudes at the end of the cycle.

The solar corona has a temperature of more than a million kelvins; the photosphere has a temperature of only about 6000 K. Why isn't the corona significantly brighter than the photosphere?

The corona has much lower density

If you had a telescope with the same-sized lens (and same focal length) as the human eye, what would be the benefit of taking an exposure of a steady light source with an integration time of 10 seconds?

The light source would appear brighter in the image.

Did the neutrino enter the reaction, or was the neutrino produced in the reaction?

The neutrino was produced in the reaction.

Then choose the condition that would make it more likely for two nuclei to fuse together.

The nuclei are moving fast with respect to one another.

What happens to the appearance of an object as it gets hotter?

The object gets bluer. The object gets brighter.

If there were two telescopes with the same diameter, but one is a visible light telescope and the other a radio telescope, how would the resolution of the images from each telescope compare? The wavelength of visible light is several hundred nanometers (1 nanometer = 10-9 meters), and radio can be several centimeters (1 cm = 10-2 meters) or several meters.

The radio telescope would have much worse angular resolution.

Telescopes that use lenses to focus light are called refracting telescopes. Bigger is better, but there is a limit to how big a lens can get before gravity distorts its shape and it can no longer focus light properly. Reflecting telescopes use curved mirrors to focus light. Gravity will also distort a mirror's shape if it gets too big. Since light passes through a lens, but bounces off a mirror, there is a fundamental difference in the way these two telescope types are designed. Mirrors are supported at the bottom, while lenses are supported at the sides by the tube surrounding them. Given that gravity pulls downward at every point on the lens or mirror, select the telescope type that can get larger (more massive) and still retain its shape.

The simpler one

Space telescopes that exist in orbit above most of Earth's atmosphere are expensive, so they must therefore be supported with a very compelling motivation. If you were trying to justify funding for a space telescope in orbit around the Earth, which of the following would be the best argument to use?

The telescope could observe wavelengths of light that are not visible from the ground.

There is a particle produced in the Sun's nuclear reactions that we can use to directly study what is happening in the interior. Neutrinos are weakly interacting particles, and they have almost no mass and no charge. They are not affected at all by the nuclear strong force. As neutrinos travel through the Sun's dense interior, how will their path change due to the presence of the gravitational, electromagnetic, and nuclear strong forces around them?

They will not change at all.

How are the wavelength and frequency related to each other?

Wavelength and frequency are inversely related.

It was discovered that there are three different types of neutrinos, called flavors, and that neutrinos can spontaneously change from one type to another. Electron neutrinos are produced in the Sun's core, but they can change into a muon or tau neutrino during their trip to Earth. The first detectors were built only to detect electron neutrinos. Can this new information solve the neutrino problem and confirm that our models of nuclear reactions in the Sun are correct?

Yes. The existence of three different types of neutrinos would account for the missing neutrinos observed over the number that were predicted.

When an electron moves from a higher energy level to a lower energy level in an atom,

a photon is emitted.

The resolution of the human eye is 1 arcminute, or 1/60th of a degree. If the light of two street lamps in the distance is separated by 0.5 arcminute, what will you see with your eyes?

a single light, with combined brightness of each street lamp

The "square" in the inverse square law for intensity of light means that

at three times the distance, the intensity is 1/9 as great.

An extremely hot object emits most of its light

at very high energies

The angular resolution of a ground-based telescope is usually determined by

atmospheric seeing

Sort each of the following particles into the appropriate bin according to the electromagnetic force it would feel in the presence of a hydrogen nucleus. The relative charge of each particle is displayed on it.

attracted toward: electron -1 repelled away: proton +1 no force felt: neutron 0

When objects get really hot, they turn

blue

Light acts like

both a wave and a particle

Cameras that use adaptive optics provide higher spatial-resolution images primarily because

deformable mirrors are used to correct the blurring due to Earth's atmosphere.

At the densities of the Sun, hydrogen nuclear fusion can occur at temperatures greater than about 10 million degrees Kelvin (K). Based on these graphs of the Sun's pressure, density, and temperature in its interior, where are the nuclear reactions occurring?

in a central region 20% the size of the entire Sun

Arrays of radio telescopes can produce much better resolution than single-dish telescopes because they work based on the principle of

interference

Refraction is caused by

light changing speed as it enters a new medium

Sunspots, flares, prominences, and coronal mass ejections are all caused by

magnetic activity on the sun

In order for an electron to jump up two energy levels in an atom at once, it requires

more energy than to jump up one energy level. a bluer photon than to jump up one energy level. a precise amount of energy.

When you turn on a lightbulb in a room, the entire room appears to flood with light at the same time. Your eyes cannot perceive light originating at the bulb and then moving outward from it. This either means that light has infinite speed (appears everywhere instantaneously), or it moves so fast that it is difficult to tell the difference.How might you improve your chances of detecting the motion of light if it moves at finite speed?

move farther away from the light source

The physical model of the Sun's interior has been confirmed by observations of

neutrinos and seismic vibrations.

If we were to take a snapshot of where the photons are inside the Sun, and which direction they are traveling, we would find that

photons are traveling in all directions.

The structure of the Sun is determined by both the balance between the forces due to _______ and gravity and the balance between energy generation and energy _______.

pressure; loss

As energy moves out from the Sun's core toward its surface, it first travels by _______, then by _______, and then by _______.

radiation; convection; radiation

Observations of excited gas in the lab show that every element, molecule, and ion has its own unique set of possible electron energy levels, as shown in the emission spectra below. Based on this fact, what can we find from the wavelengths of absorption lines seen in the spectrum of a star?

the composition of any gas between the light-emitting "surface" of the star and the observer

The surface of the Sun appears sharp in visible light because

the photosphere is thin compared to the other layers of the Sun.

The advantage of an interferometer is that

the resolution is dramatically increased

Sunspots appear dark because

they are cooler than their surroundings