* Earth's atmosphere: Our atmosphere absorbs and scatters certain wavelengths of light. This means only a small "window" of frequencies can pass through to reach our telescopes.
* Light pollution: Artificial light from cities and other sources can interfere with our ability to see fainter stars.
Here's a breakdown of the major frequency ranges we can see from Earth:
Visible light: This is the most familiar range, encompassing the colors of the rainbow from violet to red (approximately 380 - 750 nanometers). This is the range our eyes are sensitive to, and it's the most accessible for ground-based astronomy.
Near-infrared (NIR): This range (750 - 2500 nanometers) is partly absorbed by water vapor in the atmosphere but still accessible with specialized telescopes. Many cool stars and dusty regions emit strongly in NIR.
Near-ultraviolet (NUV): This range (200 - 380 nanometers) is partially absorbed by the ozone layer, but some wavelengths can be observed from high-altitude locations or space-based telescopes.
Other frequencies:
* Radio waves: These long wavelengths (from millimeters to meters) pass through the atmosphere with little absorption.
* X-rays and gamma rays: These are high-energy frequencies absorbed by the atmosphere and can only be observed with space-based telescopes.
In summary:
* Visible light is the most accessible range for ground-based observations.
* Near-infrared and some near-ultraviolet light can be observed from the ground.
* Radio waves are also accessible.
* High-energy light (X-rays, gamma rays) requires space telescopes.
Therefore, the frequency ranges of starlight observable from Earth are not continuous. They depend on the properties of our atmosphere and the available technology.
