Terrific Tools for Observing the Skies

Prisms

________ are used in binoculars to bend the light that comes from the two large lenses and two smaller lenses that you look through.

Refractors

________ use lenses to collect and focus light.

BK

________- 7 Glass: A trade term for garden- variety borosilicate glass, is often used in cheap binoculars.

Binoculars

________ are excellent for observing variable stars, searching for bright comets and novae, and simply sweeping the sky to take in the scenery.

Porro Prisms

________: These are used in relatively wide and short binoculars; they are the best kind for observing the stars because they produce brighter images with the same- sized lenses.

Giant binoculars

________ are heavy and difficult to use without a tripod or stand; many people can not use them without one.

Roof Prisms

________: These are utilized in binoculars that are comparatively straight and narrow; bird watchers prefer these.

Schmidt Cassegrains

________ and Maksutov- Cassegrains use both mirrors and lenses.

Absolute magnitude

________: The brightness of a sky object as seen from a standard distance of 32.6 light- years.

If you are observing from the Southern Hemisphere, reverse this procedure and face north

the stars rise in the east and set in the west

Absolute magnitude

The brightness of a sky object as seen from a standard distance of 32.6 light-years

Apparent magnitude

This is how bright an object appears from Earth, which is usually different from its absolute magnitude depending on how far away from Earth the sky object is located

Limiting magnitude

The apparent magnitude of the faintest star that you can see

Roof Prisms

These are utilized in binoculars that are comparatively straight and narrow; bird watchers prefer these

Porro Prisms

These are used in relatively wide and short binoculars; they are the best kind for observing the stars because they produce brighter images with the same-sized lenses

BK-7 Glass

A trade term for garden-variety borosilicate glass, is often used in cheap binoculars

BaK-4 Glass

It produces images of dim astronomical objects that are brighter and is frequently used in high-end binoculars

Northern Hemisphere

Most places in the _____ can see the Milky Way clearly both in winter and summer, high in the sky.

With an alt-azimuth mount, you can swivel the telescope up and down and side to side

in altitude and azimuth

Red Light

Best light color for stargazing.

White Light

This light diminishes your ability to see faint stars after you become dark-adapted.

Binoculars

These are excellent for observing variable stars, searching for bright comets and novae, and simply sweeping the sky to take in the scenery.

Prisms

_____ are used in binoculars to bend the light that comes from the two large lenses and two smaller lenses that you look through.

Optical Magnification

The first number in binoculars.

Aperture / Diameter

The second number in binoculars.

Higher-magnification binoculars

________ have smaller fields of view than lower-magnification binoculars, making it more difficult to locate celestial targets.

Giant Binoculars

These binoculars are heavy and difficult to use without a tripod or stand; many people cannot use them without one.

sharp points

Stars should appear as _____ when in focus and as circular images when out of focus, with smooth transitions between the two.

Refractors

_____ use lenses to collect and focus light.

Reflectors

_____ use mirrors to collect and focus light.

Newtonian reflector

In a _______, you look through an eyepiece at right angles to the telescope tube.

Cassegrain telescope

In this telescope, you look through an eyepiece at the bottom.

Schmidt-Cassegrains and Maksutov-Cassegrains

These models cost more than reflectors with comparable apertures, but they are smaller and easier to transport on observing expeditions.

alt-azimuth

With an ______ mount, you can swivel the telescope up and down and side to side — in altitude and azimuth.

equatorial

With the more expensive _____ mount, you align one axis of the telescope to point directly at the Celestial North Pole or, for Southern Hemisphere viewers, the Celestial South Pole.