- The color of light we observe is determined by the Wavelength or Frequency of light that passes through our eyes and interpreted by our brain.
- The only perceived wavelength of colors in the electromagnetic spectrum is the Visible Region, with red having the longest wavelength and violet having the shortest.
- Emission spectroscopy measures the wavelength of light emitted by electrons when they drop from a higher energy level to a lower energy level, while absorption spectroscopy measures the wavelength of light absorbed by a cooler material when a hot object passes through it.
- Properties of a star that can be determined from its spectra include:
- Surface temperature, which is based on the colors emitted by the star;
- Chemical composition, which is based from the absorption bands in its spectrum;
- Radial velocity, which uses the Doppler effect, that is, a different wavelength of light will be emitted depending on the distance of the source; and
- Rate of Rotation, which is based on the measurement of the widths of the absorption bands.
Observatory
- The types of radiation that goes through Earth’s atmosphere are Visible Light and Radio. Some Infrared and Ultra Violet also pass through. Gamma, X-rays and longer waves do not pass though the atmosphere.
- The first types of telescopes were made using refracting lenses; lights that pass through an ocular opening are magnified by a series of lenses inside the tubular body of the telescope. Years later, reflectors were used to construct smaller sizes of telescopes. Recent research telescopes now use various types of mirrors to manipulate light. Charge-couple devices are also used to collect light and convert it to digital signals, and adaptive optics have found uses in light observation. Adaptive optics employs the use of lasers and mirrors.
- Using an array of telescopes provide strong evidences on the objects that can be observed in space.
- Astronomers would most likely want to make observation from space-based telescopes as these telescopes do not have interferences resulting from the atmosphere. Moreover, it allows viewing of all the spectrum of light.
