CH. 6b Non-Optical Telescopes

The ___________ of the Hubble Space Telescope is better for shorter (bluer) wavelengths of light than for longer (redder) wavelengths of light

angular resolution

A 10-meter telescope has a larger ___________ than a 4-meter telescope.

light-collecting area

One of the first steps is to choose what type of observation to make. Recall that three basic types of astronomical observation are imaging (taking a photograph of an object), spectroscopy (spreading an object's light into a spectrum), and timing (measuring how an object's light varies with time).---Sort each of the astronomical questions below into the appropriate bin based on the type of observation you would need to perform to answer it.

Imaging= how large is the andromeda galaxy? =are stars in the Orion Nebula surrounded by dusty disks of gas? =what are the major surface features of mars? Spectroscopy= what is the temperature of Jupiter's atmosphere? =is the star Vega moving toward us or away from us? =what is the chemical composition of the Crab Nebula? Timing= does the star Mira vary in brightness? =is the x-ray emission from the galactic center steady or changing?

Different telescopes are optimized for observing different wavelengths of light, so another consideration in planning an observation is deciding what type of telescope to use.---Each of the following statements describes an astronomical measurement. Place each measurement into the appropriate bin based on the type of telescope you would use to make it.

Infrared Telescopes= determine the surface temperature of Venus. = study a dense cloud of cold gas in space. Visible Light Telescope= measure the brightness of a star that is similar to our Sun. = Obtain a spectrum of sunlight reflected by Mars. X-Ray Telescope= observe the hot (1-million K) gas in the Sun's corona. =look for high-energy radiation from a supernova. (Cool objects emit in the infrared. The Sun and similar stars emit mostly in the visible; reflected light from Mars is therefore also visible light. Very hot gas emits X rays, which have very high energy (with only gamma-ray photons having more energy for light)).

_____________ separate the various colors of light, allowing astronomers to determine stellar composition and many other stellar properties.

Spectrographs

Shown following are six different types of light that travel to Earth from the Sun. Rank these types of light from left to right based on the altitude in the atmosphere where they are completely absorbed, from highest to lowest (Earth's surface).

That is why radio telescopes and visible-light telescopes work on the surface, infrared telescopes are useful on high mountaintops or airplanes, ultraviolet telescopes can be lofted up with high-altitude balloons, and X-ray telescopes are useful only in space.

Shown following are five different colors of visible light that travel to Earth from the Sun. Rank these colors of visible light from left to right based on the altitude in the atmosphere where they are completely absorbed, from highest to lowest (Earth's surface).

all wavelengths of visible light reach Earth's surface, which is why we can see all colors and why visible-light telescopes work fine on the ground.

If our eyes were only sensitive to X-Rays, the world would appear:

dark, b/c x-ray light does not reach Earth's surface

The Chandra X-ray observatory focuses x-rays with ___________ mirrors.

grazing incidence

Where should you put a telescope designed for ultraviolet observations?

in Earth's orbit.

If you had only one telescope and wanted to take both visible-light and ultraviolet pictures of stars, where should you locate your telescope?

in space.

The twin 10-m Keck telescopes can work together to obtain better angular resolution through a technique known as ________.

interferometry

The large research observations on Mauna Kea use giant __________.

reflecting telescopes

Galileo's telescope designs using lenses were examples of ____________.

refracting telescopes

Which of the following forms of light can be observed with telescopes at sea level?

visible light, and radio waves.--Both visible light and radio waves pass almost freely through Earth's atmosphere, and therefore are easily observed with ground-based telescopes.