Telescopes Key Words

• Optical Telescopes: make use of electromagnetic radiation in the range of visible light

• Refraction Telescopes: use lenses

• Reflecting Telescopes: use mirrors

• Focal Length: the distance from the lens (or mirror) to the image formed of a distant light source

Telescopes Key Words

• Primary Lens: the main lens (the objective lens) of a refracting telescope

• Primary Mirror: the main mirror (the objective mirror) of a reflecting telescope

• Chromatic Aberration: the colour separation that occurs when light is refracted through a lens

• Radio Telescopes: make use of electromagnetic radiation in the range of radio waves

The Hubble Space Telescope

Edwin Hubble (1889-1953)

• American Astronomer• 1919 offered a staff

position at Mount Wilson Observatory, California

• Used the Hooker Telescope

• Demonstrated the existence of other galaxies

• Developed a system for classifying galaxies

• Hubble’s Law:the greater the distance between any two galaxies, the greater their relative speed of separation

• “Hubble’s Law” helped establish that the universe is expanding

The Hubble Space Telescope (HST)

The Hubble Space Telescope (HST)

• Idea for space telescope as early as the 1920s

• Received funding in the 1970s

• Carried into orbit April 1990

• Collaboration between NASA and ESA

Problem with the Hubble

• The original mirror was incorrectly shaped

• Could not focus all light to one sharp point. Fuzzy halo.

• Servicing mission in 1993

• Installed 2 new devices: like “corrective eyeglasses”

Components of the HST

The numbers• 370 miles (595km) from Earth• 43.5 ft (13m) in length• 14ft (4m) diameter• 25500lbs (11000kg)• 8 ft (2.5m) primary mirror weighs 1825lbs

(826kg)• 1ft (30cm) secondary mirror• 5 scientific instruments on board• 400million bites of info sent to Earth on a

typical day• 1000 astronomers involved in observations

per year

The Webb Space Telescope

• Successor to the Hubble Space Telescope

• Tennis court sized• Will detect infrared light. Will see it as

clearly as Hubble’s visible light.• Will orbit outside the orbit of the moon!• Launch scheduled for later in the

decade• video