astronomy #6

how do we observe invisible light

telescopes for light other than visible light often use variations on the basic design of a reflecting telescope. radio telescopes use large metal dishes as their primary mirrors. infared telescopes are sometimes cooled to very low temperature. x ray telescopes use grazing incidence reflections rather than direct reflections

interferometry uses two or more telescopes to achieve

an angular resolution equivalent to that of a much larger telescope

what do astronomers do with telescopes

imaging to create pictures of distant objects spectroscopy to study the spectra of distant objects and timing to study how a distant objects brightness changes with time

Where should you put a telescope designed for ultraviolet observations

in earth orbit

if you wanted a radio telescope to achieve the same angular resolution as a visible light telescope it would need to be

much larger

how can multiple telescopes work together

the technique of interferometry allows multiple telescopes to be linked in a way that allows them to obtain the angular resolution of a much larger telescope

how do we record images

we record images with a detector such as photographic film or a ccd. recorded images are more reliable than just seeing by eye and can record more light if we use a longer exposure time

the diffraction limit is a limit on

A telescope's angular resolution

the twinkling of stars is caused by

motion of air in our atmosphere

suppose that two stars are seperated in the sky by 0.1 arcsecond if you look at them with a telescope that has an angular resolution of 0.5 arcsecond, what will you see

One point of light that is the blurred image of both stars.

what are the two basic designs of telescopes

a refracting telescope forms an image by bending light through a lens. a reflecting telescope forms an image by focusing light with mirrors

the hubble space telescope obtain higher-resolution images than ground-based telescoped because it is

above earth's atmosphere

which technology can allow a single ground-based telescope to achieve images as sharp as those from the hubble space telescope?

adaptive optics

how does earths atmosphere affect ground based observations

earths atmosphere limits visible light observations to nighttime and clear weather. light pollution can lessen the quality of observations and atmospheric turbulence makes stars twinkle blurring their image. adaptive optics can overcome some of the blurring due to turbulence

how much greater is the light collecting area of a 6-meter telescope than a 3-meter telescope

four times

if you see the color red in an x-ray image from the chandra x-ray observatory it means

it depends: the colors are chosen arbitrarily to represent something about the X rays recorded by the telescope.

what are the two most important properties of a telescope

light collecting area, which determines how much light it gathers and its angular resolution which determines how much detail we can see in its images