7. Very Large Telescope

Imagine a car on the moon wit­h its headlights on. If you could look up at the moon and ­see each of the headlights as a distinct point of light, you'd have the observational power of the Very Large Telescope (VLT).

The VLT is actually an array of telescopes. In an array, several telescopes work together as a single unit, effectively creating one massive device. Radio telescopes -- which pick up radio waves instead of light waves -- are often used in arrays, like the Very Large Array in New Mexico, which was featured in the movie "Contact," and the Very Large Baseline Array, which stretches across the United States, from Puerto Rico to Hawaii.

The VLT is an array of optical telescopes. It consists of four 8.2-meter (26.9-ft) telescopes, each of which is a large telescope in its own right. One of those telescopes, which can operate individually, too, can pick up light 4 billion times fainter than what we can see with our eyes -- that's four times fainter than what SALT can see. There are also four smaller telescopes that act as backups to boost the system.

The VLT can join up to three of the huge telescopes into a single unit, using underground mirrors to combine light from the individual telescopes into a unified beam. The result is a telescope system that can see objects at 25 times the resolution of each telescope on its own. The ultimate goal is to be able to join together all four large telescopes into an array with the light-collecting power of a single 50-meter (165-ft) telescope.

Another take on the array approach is the type of bimirror system used in the Large Binocular Telescope, possibly the most powerful telescope in the world.