What general frequency ranges of starlight can be viewed from the surface of the earth?

Answer 1

"Viewed" means to see or behold with human eyes.

The frequency spectra arriving at the surface of the Earth is affected by the gases and existing electromagnetic field phenomenon surrounding the planet such as the Van Allen Radiation belts.

Northern lights or aurora borealis are caused by the solar ion winds and mutual magnetic field interactions.

All matter has an absorption and emission spectrum for electromagnetic radiation. When the mixture of gases surrounding the Earth are able to do so, they absorb EM photons, ionize for some period of time, then revert back to their non-ionized state by giving off energy to become energetic forms of molecules. Such is the case for oxygen gas (O2) becoming higher and higher clusters of such atoms. The next higher form of oxygen is O3 gas that is called ozone. The ozone layer of Earth's atmosphere forms due to ultra violet radiation from the Sun energizing the existing O2 gas in the atmosphere. O3 (ozone) under normal circumstances near the surface of the Earth acts as a powerful oxidizing agent similar, but not identical to the actions of chlorine gas or bleach. It would specifically irritate the lungs to produce various edema fluids there comprised of IL-2 and others. Air pollution can produce ozone with other nasty chemical byproducts whose combined effects are even worse for the lungs. Smog itself is a gas mixture of pollutants. When energized by the sun, the smog products often result in ozone gas. Smog alerts are often measured by the amount of ozone present, but smog and pollution can be present at night when the sun is not available to energize the smog molecules into a higher energy state to produce ozone. In this case, some form of laser reflection / absorption measurement instrumentation would work better night or day time. Even higher, more short lived forms of oxygen are said to briefly exist such as O5 and O6, etc.

UV-C rays from the sun are virtually eliminated prior to reaching the Earth's surface. UV-B rays from the sun that produce vitamin D precursor hormones are reduced to levels below 2% of their original strength of that prior to their contact with atmospheric gases even at the equator, but are reduced to nearly zero in latitudes away from the equator during those months when the corresponding geographic pole / axis of rotation of the Earth is pointed away from the sun, thereby requiring people living in these locations to supplement their diets with vitamin D so that they do not suffer its deficiency. The atmosphere in these cases presents a more shallow angle of incidence so that the incoming photons must travel a greater distance through the atmosphere prior to them arriving at the surface.

Water vapor is a gas that can be seen as clouds. The color of clouds when light is directed upon them is white, and as such a very wide spectrum of light is reflected or blocked when the weather is cloudy and thick enough that the clouds produce shadows or shade.

Although some conspiracy theory debunkers claim that chemtrails do not exist, scientists have been performing experiments that they call "direct radiative forcing of aerosols". Search engine hits for this come up from MIT scientists and many others.

A keyword search for >"international aspects of weather modification" president< will turn up search results of NSDM 165 that was a US Presidential memo written in the time of Richard Nixon in the 1970s. It demonstrates that various schemes from even decades before that were improving weather modification weaponry that is in force to this day and no doubt has advanced to a much higher level of sophistication--who said that the government can't keep any secrets?

Another application of the so called chemtrails is that of "over the horizon" radar defense tracking systems. A keyword search for >2003 Edmonton us air force spraying radar barium aluminum< will turn up a verified account of such an application. These metal materials when placed into the atmosphere would modify its electromagnetic absorption, reflection, and transmission properties (possibly bending the direction of flow of the radiation).

Earth-based EM emissions could also cause interference patterns in the waves of incoming radiation. HAARP (High-frequency Active Auroral Research Program) could modify many aspects of the atmosphere--including weather. Other countries than the USA are said to possess virtually identical technology to the HAARP equipment. Some people claim that HAARP energy can be directed at specific targets to cause earth quakes or weather anomalies. When active, the sky around the intended target of the HAARP energy appears like an oily rainbow in the sky.

So, the spectrum of EM radiation reaching the Earth's surface would depend on your geographic location, the time of day to determine the effect of the sun on atmospheric gases (to create more water vapor for example, or ionized / magnetized northern lights), pollution / smog levels, and existing weather such as clouds. The atmosphere and magnetic field and EM sources would have a variable band pass effect on the EM frequency spectrum able to reach the Earth's surface.