Astronomy 101(beginner's guide to the universe 7th edition) Chapter 3

Optical

_______ telescopes are reflectors or refractors. Reflectors focus light by reflecting it with a mirror, refractors focus light by bending it through a lens.

Reflectors

__________ focus light by reflecting it with a mirror

refractors

__________ focus light by bending it through a lens.

Reflectors, refractors

__________ are preferred over __________ for several reasons. First, supporting a large mirror is a lot easier than supporting a large lens because the lens has to be supported on its edge only. Lenses can cause chromatic aberration—light gets separated out by wavelength and hence blurred. Lenses require two optically polished surfaces whereas mirrors require only one. Some of the incident light may be absorbed and lost when passing through a lens.

Resolution

__________ is a measure of how easily two objects can be distinguished from each other, and is increased with telescope size.

optical

*The atmosphere can blur light before it reaches a ground based _______ telescope. This is why telescopes are often placed high on mountaintops in dry areas. Adaptive optics may be used as well to correct for atmospheric blurring.

Adaptive

________ optics may be used as well to correct for atmospheric blurring.

Atmospheric turbulence

___________ __________ is what can cause stars to appear to be twinkling even when they are not.

Radio

_____ astronomy can be done from the surface of the earth at all hours of the day and in all weather because _____ waves are not impeded by cloud cover nor interfered with by the sun's light. This is because _____ waves are much longer than visible light. _____ telescopes tend to be much larger than optical telescopes and often interferometry is used was well. This is because it is difficult to get good resolution with _____ telescopes due to the size and weakness of _____ waves.

visible

radio waves are much longer than _______ light.

radio waves

it is difficult to get good resolution with radio telescopes due to the size and weakness of _____ _____.

atmosphere

Doing astronomy at other wavelengths requires getting out of the earth's __________. There are space based infrared, ultraviolet, X-ray and gamma ray telescopes. Infrared and UV telescopes operate in much the same way optical telescopes do. X-ray telescopes require using mirrors where the x-rays are incident at a grazing angle because otherwise the x-rays would pass right through the mirrors. Gamma ray telescopes employ techniques used in particle accelerators for measuring incoming gamma rays.

space

There are _____ based infrared, ultraviolet, X-ray and gamma ray telescopes.

Infrared, UV

_________ and __telescopes operate in much the same way optical telescopes do.

X-ray

_____ telescopes require using mirrors where the _____s are incident at a grazing angle because otherwise the _____s would pass right through the mirrors.

Gamma ray

_____ ___ telescopes employ techniques used in particle accelerators for measuring incoming _____ ___s.

Hubble

Some optical telescopes are also placed in space to eliminate atmospheric blurring. The ______ space telescope is the most famous example of this.

terrestrial

Mercury, Venus, Earth, and Mars are the ___________ planets—they are dense and rocky and have solid surfaces.

Jovian

Jupiter, Saturn, Uranus, and Neptune are the ______ planets. They are the gas giants—not very dense, composed primarily of gas, and they do not have solid surfaces. ______ planets experience differential rotation—where their equators rotate at different rates than their polar regions.

differential

Jovian planets experience ____________ rotation—where their equators rotate at different rates than their polar regions.

Mercury

________ is the smallest planet and the closest to the sun. It is also the fastest planet. It rotates three times around its axis every two times it revolves around the sun. It has little atmosphere and as a result has very extreme surface temperatures.

Venus

_____ is closets to us in size. It has an extremely dense carbon dioxide rich atmosphere. As a result, it has a run-away greenhouse effect that makes the surface very hot. _____ rotates about it's axis in the opposite direction as the other planets. It is the brightest object in our sky except for the sun and moon.

Earth

_____ is our home planet. It is thus far the only place where we've found life. It has liquid water covering ¾ of its surface. Its axial tilt gives it seasons. It has one moon.

Mars

____ appears red due to a layer of iron oxide on its surface. ____ has surface features that suggest it once had liquid water on its surface. We have sent missions to ____ to try to find water and test for microbial life. It has two moons.

iron oxide

Mars appears red due to a layer of ____ _____ on its surface.

asteroid belt

The ________ ____ lies between the orbits of Mars and Jupiter and is composed primarily of small rocky bodies called asteroids and meteoroids. Ceres is the largest object in the asteroid belt and it is a spherical dwarf planet.

Ceres

_____ is the largest object in the asteroid belt and it is a spherical dwarf planet.

Jupiter

_______ is the largest of all the planets. This gas giant contains most of the mass of the entire solar system except for the sun. It has more than sixty moons, including the four Galilean moons discovered by Galileo. _______'s giant red spot is a storm that has been raging on its surface for hundreds of years. _______ also has a ring system.

Saturn

______ is best known for its extensive and bright ring system. This is the second largest of the planets. ______ also has several moons. ______ is the least dense of all the planets—it is less dense even than water.

Uranus

______ is a blue-green planet that is tipped on its side. Its 98 degree axial tilt causes it to have extreme seasons. It gets its color primarily from the methane in its atmosphere. ______ has moons and rings.

methane

Uranus gets its color primarily from the _______ in its atmosphere

Neptune

_______ is the outermost planet. It is blue due to the methane in its atmosphere. It has been photographed showing a great dark spot that is the result of a large storm(much like the red spot on Jupiter.) _______ has moons and rings.

Kuiper belt

The ______ ____ is a belt composed primarily of icy bodies orbiting beyond Neptune. In this belt are several dwarf planets, including Pluto.

dwarf

With the discovery of several spherical bodies in the belts that were orbiting the sun just as Pluto does, the question was raised as to whether to call these objects planets or to downgrade Pluto's status as a planet. The decision was made to refer to these objects(and Pluto as well) as _____ planets because they are like planets in every other way with the exception that they have not cleared their neighborhoods of debris.