The Great Observatories

I find it sort of startling that if you asked a good portion of people on this planet the names of the four gospels, they will name them correctly, no sweat ("Bill, Bob, Fred, and Mary"), but they will not be able to name the four space telescopes.

The four telescopes I am talking about are what NASA calls the Great Observatories. 

NB: To be honest, there are many more than four space telescopes at the moment, but let's not have the details get in the way of a good story, shall we.

For those who are curious, the four space telescopes are named below.

Compton, which operates in the gamma ray spectrum.

Chandra, which operates in the X-ray spectrum.

Hubble, which is an optical telescope, and therefore operates in the visible light spectrum.

Spitzer, which operates in infrared, and is now deactivated. The James Webb Space Telescope also operates in infrared, so I don't know if NASA is considering a replacement for Spitzer.

Why do we put telescopes in space? 

Ground based telescopes suffer from atmospheric interference. Optical telescopes have to account for weather and well, daylight. X-ray telescopes are useless on the ground because Earth's atmosphere absorbs X-rays (Note: This is a Good Thing^TM).

Putting a telescope in space eliminates an entire set of observation problems. The skies are really clear up there, so to speak.

Okay, but why do we need telescopes that operate outside of visible light? Why can't we get away with just putting optical scopes like Hubble in space and calling it a day?

Visible light is not the only way to see things and understand them.

For example, extreme high-energy events like supernovae emit tremendous quantities of gamma rays, which are high on the spectrum, well past the frequency of visible light. Neutron stars and pulsars also emit gamma rays. Best way to study these--you guessed it--are telescopes that can collect gamma rays.

Young stars are born in nebulae. These stars are often completely obscured by huge clouds of gas and dust. Visible light does not penetrate these clouds, but infrared does. These stars are invisible to optical telescopes. Enter infrared telescopes.

The universe is speaking to us in many languages. The space telescopes are the interpreters.