Instruments Used in Astronomy

Optical Telescopes

• Used to observe visible light from celestial objects.
• Types:
  
  • Refracting Telescope: Uses lenses to bend light and form an image.
  • Reflecting Telescope: Uses mirrors to reflect light and form an image.
• Important features:
  
  • Aperture: Diameter of lens or mirror, determines light-gathering ability.
  • Magnification: Ratio of focal length of objective to eyepiece.
• Examples: Hubble Space Telescope (uses mirrors, space-based).

Spectroscope / Spectrometer

• Used to split light from stars or galaxies into its spectrum.
• Applications:
  
  • Identify chemical composition of stars (emission and absorption lines).
  • Determine redshift or blueshift, giving information about motion.

Radio Telescopes

• Detect radio waves emitted by celestial objects.
• Large parabolic dishes collect weak radio signals.
• Applications:
  
  • Study pulsars, quasars, cosmic microwave background.
  • Observe through interstellar dust clouds that block visible light.

Photometers / CCD Cameras

• Measure brightness (intensity) of stars and other objects.
• CCD (Charge-Coupled Device) cameras convert light into electronic signals for imaging.
• Applications:
  
  • Monitor variable stars, eclipsing binaries.
  • Capture high-resolution images of planets, galaxies, and nebulae.

Space Telescopes

• Telescopes placed in space to avoid atmospheric distortion and absorption.
• Examples:
  
  • Hubble Space Telescope – optical, UV, infrared observations.
  • James Webb Space Telescope – infrared observations for distant galaxies.

Other Instruments

• Interferometers – combine signals from multiple telescopes to improve resolution.
• Coronagraphs – block light from the Sun to observe its corona.
• Gravitational wave detectors (e.g., LIGO) – detect ripples in spacetime from cosmic events.

Comparison Table of Astronomical Instruments