Final answer:
Images of our galaxy are derived by using other forms of light, such as infrared and radio waves, to penetrate the dust and study the Milky Way. Astronomers also observe nearby galaxies and measure the dimming of their light to estimate the distance and true luminosity of our galaxy. Dark matter, which cannot be directly observed, is detected through its gravitational influence on visible matter, but its composition and quantity remain a mystery.
Step-by-step explanation:
The images of our galaxy are derived through a combination of observations and data analysis. Since visible light is partially blocked by dust, astronomers use other forms of light that can penetrate the dust, such as infrared and radio waves, to study the Milky Way. By observing nearby galaxies that resemble ours and measuring the dimming of their light, astronomers can estimate the distance and true luminosity of our galaxy.
Additionally, recent discoveries indicate the presence of dark matter, a component of the galaxy that cannot be directly observed. Dark matter is detected through its gravitational influence on visible matter, but its composition and quantity are still unknown.
It is important to remember that visible light only represents a small portion of the electromagnetic spectrum, and astronomers use instruments that can detect other types of waves to gather more comprehensive information about the universe.