BIO 475 Lecture Notes - Lecture 21: Gamma Ray, Black Body, Positron
Light on Coral Reefs
● Thermo-Nucluear Fusion (happening in the sun)
○ Protons, two of them merge and release positron and gamma ray.
■ Positron is same thing as an electron, just a positive charge
■ Electrons make up most of the matter we know of, positrons is the
opposite, when they meet they annihilate each other , releasing a large
amount of energy and a photon
○ Neutrino
■ Sub atomic particles
■ Go into nothingness
○ Then get a proton and neutron, forming a nucleus of an atom
○ Another proton joins and releases another gamma ray
■ Gamma ray: high intensity photon
■ Takes years for gamma rays to leave sun
■ When a photon meets a molecule, it excites the electron, which falls and
releases another photon; which is less energetic than the gamma ray.
● The less powerful photons leave the sun, not the gamma ray
○ What we see as light
○ WHen they join back together they spit out protons and end up with helium
nucleus
○ Under high pressure and temperature
■ light elements make heavier elements
○ This process makes light/photons
● Black Body radiation
○ Sun is a black body, as well as other stars
○ Earth radiates heat upwards
○ Heat is long wave radiation ; light
○ Graph
■ Spectral Radiance= intensity of light
■ Heat is at like 10 micrometers
■ If sun was a perfect emitter of light it would have the smooth curve
■ Not an accident that we evolved to see these colors, the sun has been
emitting these wavelengths for years
■ Micro metter is 1/millionth of meter
○ Black bodies are perfect emitters
■ Colors of light they emit depend on how hot they are
○ Sun is 5500K
● Extraterrestrial Solar Radiance
○ Spectrum of the sun
○ .5 Micrometers is 500 nm
○ What the sun's energy looks like outside the Earth’s atmosphere
○ Sun has an atmosphere that absorbs light
○ .4-.7 micrometers visible light
● Solar Radiation at Earth's Surface
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Document Summary
Protons, two of them merge and release positron and gamma ray. Positron is same thing as an electron, just a positive charge. Electrons make up most of the matter we know of, positrons is the opposite, when they meet they annihilate each other , releasing a large amount of energy and a photon. Then get a proton and neutron, forming a nucleus of an atom. Another proton joins and releases another gamma ray. Takes years for gamma rays to leave sun. When a photon meets a molecule, it excites the electron, which falls and releases another photon; which is less energetic than the gamma ray. The less powerful photons leave the sun, not the gamma ray. When they join back together they spit out protons and end up with helium nucleus. Under high pressure and temperature light elements make heavier elements. Sun is a black body, as well as other stars. Heat is long wave radiation ; light.
