NJIT PHYSICS 203 EARTH IN SPACE COMPREHENSIVE
STUDY GUIDE 2026 FULL QUESTIONS AND SOLUTIONS
GRADED A+
● Refracting Telescope. Answer: Optical telescope using lenses to collect and focus light
● Reflecting Telescope. Answer: Optical telescope using mirrors to collect and focus light
● Cassegrain Telescope. Answer: Reflecting telescope where light reflects off a secondary
mirror back through the primary
● Newtonian Telescope. Answer: Reflecting telescope with a flat secondary mirror directing
light to the side
● Schmidt-Cassegrain. Answer: Compact telescope using a corrector plate and Cassegrain
design
● Aperture. Answer: Diameter of the primary lens or mirror determining light-gathering ability
● Light-Gathering Power. Answer: Proportional to the square of a telescope's aperture
● Focal Length. Answer: Distance from a lens or mirror to the point where parallel light is
focused
● Focal Ratio. Answer: Ratio of focal length to aperture also called f-number
● Angular Resolution. Answer: Smallest angle between two objects a telescope can
distinguish
● Diffraction Limit. Answer: Theoretical maximum resolution set by the wave nature of light
● Rayleigh Criterion. Answer: Minimum angular separation for two point sources to be
resolved
● Seeing. Answer: Atmospheric turbulence limiting ground-based telescope resolution
● Adaptive Optics. Answer: Technology correcting atmospheric distortion in real time
● Active Optics. Answer: System that adjusts mirror shape on long timescales to maintain
figure
, ● Interferometry. Answer: Combining light from multiple telescopes to achieve very high
resolution
● Baseline. Answer: Separation between telescopes in an interferometer determining
resolution
● VLBI. Answer: Very Long Baseline Interferometry using widely separated radio dishes
● Radio Telescope. Answer: Large dish or array collecting radio waves from space
● Arecibo Observatory. Answer: Former large single-dish radio telescope in Puerto Rico
● VLA. Answer: Very Large Array a 27-dish radio interferometer in New Mexico
● Event Horizon Telescope. Answer: Global network of radio telescopes imaging
supermassive black holes
● Hubble Space Telescope. Answer: Orbiting optical telescope avoiding atmospheric
distortion
● Spitzer Space Telescope. Answer: NASA infrared space telescope now retired
● Chandra X-ray Observatory. Answer: Orbiting X-ray telescope studying high-energy
phenomena
● Fermi Gamma-Ray Space Telescope. Answer: Orbiting gamma-ray observatory studying
energetic cosmic phenomena
● CCD. Answer: Charge-Coupled Device detector converting photons to electrons for digital
imaging
● Photometry. Answer: Measurement of light intensity from astronomical sources
● Astrometry. Answer: Precise measurement of positions and motions of celestial objects
● Proper Motion. Answer: Star's transverse velocity across the sky measured in arcseconds
per year
● Space Motion. Answer: Star's full three-dimensional velocity combining proper motion and
radial velocity
● Magnitude Scale. Answer: Logarithmic scale where each step of one magnitude equals a
factor of 2.512 in brightness
STUDY GUIDE 2026 FULL QUESTIONS AND SOLUTIONS
GRADED A+
● Refracting Telescope. Answer: Optical telescope using lenses to collect and focus light
● Reflecting Telescope. Answer: Optical telescope using mirrors to collect and focus light
● Cassegrain Telescope. Answer: Reflecting telescope where light reflects off a secondary
mirror back through the primary
● Newtonian Telescope. Answer: Reflecting telescope with a flat secondary mirror directing
light to the side
● Schmidt-Cassegrain. Answer: Compact telescope using a corrector plate and Cassegrain
design
● Aperture. Answer: Diameter of the primary lens or mirror determining light-gathering ability
● Light-Gathering Power. Answer: Proportional to the square of a telescope's aperture
● Focal Length. Answer: Distance from a lens or mirror to the point where parallel light is
focused
● Focal Ratio. Answer: Ratio of focal length to aperture also called f-number
● Angular Resolution. Answer: Smallest angle between two objects a telescope can
distinguish
● Diffraction Limit. Answer: Theoretical maximum resolution set by the wave nature of light
● Rayleigh Criterion. Answer: Minimum angular separation for two point sources to be
resolved
● Seeing. Answer: Atmospheric turbulence limiting ground-based telescope resolution
● Adaptive Optics. Answer: Technology correcting atmospheric distortion in real time
● Active Optics. Answer: System that adjusts mirror shape on long timescales to maintain
figure
, ● Interferometry. Answer: Combining light from multiple telescopes to achieve very high
resolution
● Baseline. Answer: Separation between telescopes in an interferometer determining
resolution
● VLBI. Answer: Very Long Baseline Interferometry using widely separated radio dishes
● Radio Telescope. Answer: Large dish or array collecting radio waves from space
● Arecibo Observatory. Answer: Former large single-dish radio telescope in Puerto Rico
● VLA. Answer: Very Large Array a 27-dish radio interferometer in New Mexico
● Event Horizon Telescope. Answer: Global network of radio telescopes imaging
supermassive black holes
● Hubble Space Telescope. Answer: Orbiting optical telescope avoiding atmospheric
distortion
● Spitzer Space Telescope. Answer: NASA infrared space telescope now retired
● Chandra X-ray Observatory. Answer: Orbiting X-ray telescope studying high-energy
phenomena
● Fermi Gamma-Ray Space Telescope. Answer: Orbiting gamma-ray observatory studying
energetic cosmic phenomena
● CCD. Answer: Charge-Coupled Device detector converting photons to electrons for digital
imaging
● Photometry. Answer: Measurement of light intensity from astronomical sources
● Astrometry. Answer: Precise measurement of positions and motions of celestial objects
● Proper Motion. Answer: Star's transverse velocity across the sky measured in arcseconds
per year
● Space Motion. Answer: Star's full three-dimensional velocity combining proper motion and
radial velocity
● Magnitude Scale. Answer: Logarithmic scale where each step of one magnitude equals a
factor of 2.512 in brightness
