The Basics of Astronomy
The Study of Light
Thanks to Science Fiction, movies, and the recent Mars expeditions many people have the Idea that Astronomy is all about sending robots into space, collecting rocks, and exploring other planets. In truth Astronomy is largely a study of Light.
The furthest our technology can send Humans, at least currently, is to the Moon. In terms of the Model where the Sun was a grapefruit and the Earth 15 meters from the Sun, we’ve managed to travel a Staggering 4cm. Mars is over 200 times that distance, sending rovers is about the best we can expect for the next century or so. So clearly most of what we know about the Universe is not from actually going to places, but it is from studying the light that comes from these places.
Light, also known as Electromagnetic Radiation, comes in a variety of forums. We are familiar with Visible Light, which is just a small fraction of what is known as the Spectrum of Light. Light is most easily conceived of as a wave, which means we can Describe Light in terms of Wavelength and Frequency. Research these terms on your own, the Important thing to know is that Light is usually described by its Wavelength (which tells you about its Frequency as well). Light in the Visible spectrum has Wavelengths from about 400 nm to 700 nm (a nm, or nanometer is one million times smaller than a meter), but Light can exist at any wavelength. The wavelength of Light also tells you about the Energy in the Light, generally the shorter the Wavelength, the more Energy.
The entire Spectrum of light (or the Electromagnetic Spectrum as it is often called) relates Light of all wavelengths. You’ve likely heard of the varying types of light, and are pretty familiar with many of them. Infrared light is the Light that has wavelengths just larger than 700 nm, and is the light given off by Warm objects such as Humans. In order of short wavelength to longer the spectrum is like this; Gamma Rays, X-rays, Ultraviolet, Visible light, Infrared, and Radio waves (microwaves are technically low wavelength Radio waves).
How is all this Important to Astronomy? Well Since light is all we have to Observe most of the Universe by, it is important we use every bit of Light available. Astronomers have Telescopes that can capture “Images” in a variety of Wavelengths as many things just aren’t visible in the Wavelengths our eyes can see. For example it is easiest to see Stars forming in the Infrared because that is the Wavelength of Light they produce the Most.