Astronomy A: Unit 2 - Lesson 4-6

Another name for the compound lens is the _______ lens or _______ lens.

- achromatic - doublet

A mixture of two or more metals is called a(n) _____.

alloy

Data was better preserved when _____ were mounted on telescopes.

cameras

The electronic replacement for the camera is the _____, or charge-coupled device, which can also collect light from very dim objects.

CCD

_______ was the inventor of the compound lens.

Chester Hall

Why was the Cassegrain telescope important?

It made the reflecting telescope easier to use by cutting the length of tube needed to bring light into focus in half.

_____ means to dim the shine of.

Tarnish

Any telescope that depends on lenses for operation is called a(n) _______ telescope.

refracting

A telescope is a mechanism for extending and enhancing the sense of _______.

sight

Due to its _____ size, a CCD can only collect images of a very small slice of the night sky in one exposure.

small

Newton used the alloy _____ to form the concave mirror needed for his invention.

speculum

_____ was used to coat glass, creating a highly reflective surface that was lighter and cheaper than speculum.

Silver nitrate and sugar

_____ came up with the idea for multiple-mirror telescopes.

Edward Synge

1- the failure of a lens to bring all light rays to a single focus 2- pertaining to color 3- a ring of light surrounding an object 4- pertaining to Earth 5- a convex and concave lens placed back-to-back, with the result being a finer or better-quality image

1- aberration 2- chromatic 3- halo 4- terrestrial 5- compound lens

When viewed on its edge, a concave mirror would look like:

C

_____ invented the reflecting telescope because he believed the disappointing characteristics of refracting lenses would never be overcome.

Isaac Newton

_____ refers to a special curve looking like the inside of a bowl.

Parabolic

In 1789, _____ discovered the sixth and seventh moons of Saturn, Enceladus, and Mimas.

William Herschel

Alignment of each segment making up the mirror of the Keck telescope is established and maintained by a(n) ______ system.

active-alignment

A camera can collect light from very _____ objects for hours at a time.

dim

The front lens directs incoming light down the tube to the _______ or rear lens for viewing.

eyepiece

The bigger the _______ lens, the more detail may be seen.

front

A wide mirror gathers more _____ light than a narrow one.

incoming

The function of the objective lens is to gather more _______ than is possible for the human eye.

light

The front lens of a refracting telescope is the _______ lens.

objective

Newton's reflecting telescope has been a major means by which our knowledge of _____ has increased.

the universe