The Main Characteristics of the Emits - Essay Example

As the temperature increases, the blackbody starts to emit visible light, starting from red to orange, yellow to white and blue with increasing temperature. When the blackbody turns white, it is already emitting ultraviolet radiation. Stefan’s Law states that the total energy radiated by a blackbody per unit surface area is directly proportional to the fourth power of its absolute temperature. This means that as temperature increases, the wavelength of the radiation emitted decreases.

Doppler Effect, or Doppler shift, happens when an observer is moving relative to the wave source – there is a change in the frequency of the wave perceived by the observer. This means that when we are approaching the wave source, we perceive a higher frequency. When we are receding from the wave source, we perceive a lower frequency.
Spectroscopy refers to the dispersion of an object's light into its component colours. By analyzing the light emitted by an object, the physical properties of that object such as temperature, mass, luminosity and composition can be inferred by an astronomer. Continuous spectrum, as opposed to discrete spectrum, refers to energy at all wavelengths. It is emitted by warm objects. The spectrum of light with missing frequencies is called the absorption spectrum. The missing frequencies correspond to wavelengths of light that were absorbed.

Suppose that a beam of light passes through a gas, some of the frequencies of the light will be absorbed by the gas. The rest of the frequencies will be able to pass through. When these surviving frequencies are dispersed through a prism, they will show a spectrum with gaps on it. The visible spectrum will correspond to the emission spectrum while the dark bands will correspond to the absorption spectrum.

Refractors tend to be heavier overall than reflecting telescopes because of their longer solid tubes and require a larger housing and a more massive mount. Reflectors don't disperse colour as most refractors are to one degree or another. In a refractor, the lens can only be supported along the edge so that the path is clear for light to come through unobstructed. The Earth's atmosphere is constantly moving, and different layers bend the light from a star in different directions, blurring our view from the ground.

The major advantages of CCD-based cameras are their light-gathering efficiency, linear behaviour, cooling operation, digital images, and immediate image availability. The CCD detector is a highly-efficient collector of photons. Views of objects on Earth in different wavelengths vary. The main advantage of studying objects at different wavelengths is that we can study selected features of that object.