Module 6 HW 30/30
Which of the following is the biggest disadvantage of putting a telescope in space?
Space telescopes are much more expensive and riskier than similar ground-based telescopes
Spacecraft are the most effective way to study planets in our Solar System because:
Spacecraft can collect more information than is available just from images from Earth
Improved resolution is helpful to astronomers because it enables them to view
Very distant objects Many objects close together Small features of an object
The largest astronomical refractor has an aperture of 1 meter. Select all true statements below about why it would be impractical to build an even larger refractor with, say, twice the aperture.
-The degree of chromatic aberration increases as the focal length gets longer, and this would reduce image quality -The tube would have to be so long that housing and moving it would be extremely difficult, especially because it would be frontloaded with weight -A lens with a 2 m diameter would be very heavy and would deform under its own weight within a few years
Review the spectrum here. Remembering that earth has an atmosphere how much of each type of light can we see. (0.33%)
1 - B 2 - C 3 - A
Match the following properties of telescopes with their corresponding definitions.
1 - F 2 - C 3 - A 4 - B 5 - D 6 - E
There are many types of telescopes both on the ground and in space. Sort these telescopes by the type of light they observe.
1 - Radio 2 - X-ray 3 - Visible 4 - Gamma ray 5 - Microwave 6 - Infrared
Some surfaces have experienced more recent geological activity (like volcanism or erosion) that wiped out previously existing craters. They are referred to as "geologically younger" than surfaces that have not experienced activity. We can therefore use crater counts to determine the "age" of a surface, approximating how long ago the last geological event occurred in that area. Using this technique, rank the surfaces in order of their geological age, from oldest to youngest. For simplicity, you may assume that the surface areas covered by each image are the same, so that an image with more craters also has a higher crater density. Make sure to carefully consider craters of all possible sizes.
1. Youngest - A 2. - B 3. Oldest - C
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.
A - 1 easy to detect B - 2 C - 3 difficult to detect
Today's astronomers have a broad array of technological tools for capturing astronomical data. Early astronomers lacked that advantage. Place the following types of astronomical equipment in the order that they became available.
A - 5 B - 1 C - 2 D - 3 E - 4
Refracting, Newtonian, and Cassegrain telescopes are some of the most common types of telescopes used for astronomical observations. A refracting telescope bends light as it passes through a primary lens. The reflecting Newtonian telescope allows astronomical images to be viewed from the side. The Cassegrain is a reflecting telescope design currently used by large telescopes. Each image shown depicts how light travels inside a particular type of telescope. Analyze each image and identify which type of telescope it is.
A - Newtonian B - Refracting C - Cassegrain
The four planets closest to the Sun have similar compositions (rock/metal), and all have solid surfaces. They are therefore grouped together as terrestrial ("Earth-like") planets. Even though they formed from the same process of accretion in the Solar Nebula, you'll see here that their surfaces are significantly different from one another.
A - Volcanism/tectonics B - Erosion C - Impacts
The angular resolution of a ground-based telescope is usually determined by
Atmospheric seeing
The level of each of the surface-shaping processes that occur on a planet throughout its history will determine how its surface appears. The terrestrial planets were formed in basically the same environment, so we can assume that the average frequency of impacts for all of the terrestrial planets has been about the same. In a hypothetical scenario where impacts are the only process that ever shapes planetary surfaces, how would the surfaces of the terrestrial planets compare?
All of the planets would have roughly the same number of craters per area
In practice, the smallest angular size that you can resolve with a 10-inch telescope is governed by the:
Blurring caused by Earth's atmosphere
CCD cameras have much higher quantum efficiency than other detectors. Therefore, CCD cameras:
Can generate a signal from fewer photons
The similarity of Mars's tiny moons to asteroids suggests that they wandered away from the nearby asteroid belt and were captured by Mars's gravity. It is difficult to explain, however, how a relatively small planet like the Earth would be capable of capturing an object as large as the Moon. If it wasn't captured, then it must have either formed simultaneously with the Earth or separated from the Earth due to some event that happened later. We can get an idea of which scenarios are reasonable by looking at the composition of the two, which we can gather from their densities. Examine the figure below, which shows the approximate density of the Earth's layers in g/cm3. If the density of the Moon is 3.34 g/cm3, which layer of the Earth is it most similar to?
Crust
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
High-performance computers have become one of an astronomer's most important tools. Which of the following require the use of that type of computer?
Generating and testing theoretical models Analyzing images taken with very large CCDs Studying how astronomical objects or systems evolve
Arrays of radio telescopes can produce much better resolution than single-dish telescopes because they work based on the principle of
Interference
Comparing objects in our Solar System can give us important clues toward understanding their properties that we wouldn't obtain through just studying each object independently. Comparing Earth's Moon to those of the other planets may also help us understand more about it. Examine this table and choose the statements below it that match your observations.
Only half of the inner planets have moons The Earth's Moon is unique in that it is much larger than the moons of the other inner planets
Based on the images of the moons and the properties of the objects listed, which of the following statements is correct?
Phobos and Deimos have properties that suggest that they are the same type of object as c-type asteroids.
You are shopping for telescopes online. You find two in your price range. One of these has an aperture of 20 cm, and one has an aperture of 30 cm. Which should you choose, and why?
The 30 cm, because the light-gathering power will be better.
It is unlikely that the Moon formed elsewhere and was captured by Earth's gravity, since it may be impossible for the Earth to capture an object as large as the Moon. It is also of note that the Moon contains an unusually low quantity of volatiles, which are materials like water that are easily vaporized at high enough temperatures. Based on this, and given the Moon's density, which of the following formation scenarios of the Moon most closely matches our observations?
The Moon accreted from the debris of the impact of a large object with the surface of the Earth
Observations show that, in general, larger planets and moons have had geological activity more recently than smaller bodies have. All of the planets show past signs of volcanism, tectonics, and/or erosion, but only the larger ones are still geologically active today. Why is this? One reason has to do with the planet's interior. Most of the heat inside of Earth is left over from the accretion process during Earth's formation. What would you expect to have happened as the Earth (or any other planet) cooled after its formation?
The hard crust thickened, closing off volcanic vents, and the mantle began to solidify, slowing the motion that causes volcanism and tectonics
How would you explain the difference in cratering between these two pictures?
The surface on the right has experienced more recent volcanism or erosion than the surface to the left
Why are all large astronomical telescopes reflectors (choose all reasons that apply)? (0.67%)
They can be shorter They are not as heavy
Choose all that apply. CCD cameras are better astronomical detectors than the human eye because
They can observe at wavelengths beyond the visible Their quantum efficiency is higher The integration time can be longer
Why are neutrinos so difficult to detect?
They don't interact strongly with matter, so they will not cause a reaction on a CCD imager
