STUDYING SPACETelescopes

Telescope

• An instrument that collects electromagnetic radiation from objects in space

• Concentrates the electromagnetic radiation for better observation

Optical Telescopes

Most common type of telescope

Used to study visible light from objects in universe

Enables you to see millions of stars

Refracting Telescopes

Use lenses to gather and focus light

Two Disadvantages of Refracting Telescopes

1. Images cannot be perfectly focused

2. Size of objective lens limits the size of the telescope

Reflecting Telescopes

Use a curved mirror & a flat mirror to gather & focus light

Three Advantages of Reflecting Telescopes

1. Large mirrors can gather more light.

2. Flaws in the mirror’s glass do not affect the light.

3. Mirrors can focus all colors of light at the same time.

Optical Telescopes & Atmosphere

Air above telescope makes starlight shimmer & blur.

Light pollution affects ability to see dim objects.

Placement of Telescopes

Dry environments

Mountaintops Less light pollution Less air pollution Air is thinner

Space

Electromagnetic Spectrum

Detecting Electromagnetic Radiation

EM spectrum = all of the wavelengths of

electromagnetic radiation

Each color of light is a different wave-

length.

Humans can see radiation from red light

(long wave) to blue light (shorter wave).

Nonoptical Telescopes Used to study

invisible radiation

Each type of EM radiation gives different clues about objects

Detecting Electromagnetic Radiation Visible light is small part of EM

spectrum.

Most of EM spectrum is invisible Radio waves (longest waves) Microwaves Infrared waves Ultraviolet waves X-rays Gamma waves (shortest waves)

Radio Telescopes

Detect radio waves

Can be linked with other radio telescopes

Surface does not have to be solid

Must be much larger than optical telescopes Radio waves can be as large as a

building

Radio Telescope & VLA

Nonoptical Telescopes in Space

Placed in space because most EM radiation is blocked by Earth’s atmosphere