You probably haven't thought much about having a hard time seeing big things. After all, big things are big, right? That usually makes them easy to see.
But what about big things that are far, far away? Some of the biggest things in our universe — planets, stars, solar systems, entire galaxies — are also millions and millions of light years away. (A light year is the distance light travels in one year, which is about 6 trillion miles!)
Other parts of our solar system, like the outermost planets, are farther from Earth than the sun. For example, Neptune is about 3 billion miles away from Earth.
Although Neptune is about four times larger than Earth (based on diameter), we can't see Neptune with the naked eye because it's so far away.
Thanks to the curious minds of early scientists, though, a tool was invented long ago that helps us to extend our sight into the great beyond to see some of the biggest things in the universe, even if they're millions of light years away. What was it? The telescope!
Who invented the telescope? Many people believe Galileo Galilei invented the telescope, because his telescope was the first to be used for astronomy in 1609.
Telescopes use glass lenses or mirrors to create images, much like cameras. By combining different types and sizes of lenses, telescopes allow users to view objects that are very far away.
Since its launch in 1990, this powerful telescope floats in outer space and allows us to see much farther than ever before. It continues to provide never-before-seen views of the farthest reaches of the universe, including entire galaxies that astronomers never knew existed.
Astronomers are excited about the future of telescopes, too. In fact, the most powerful and scientifically advanced optical telescope on Earth is scheduled to be built atop Mauna Kea mountain in Hawaii. It will be called the "Thirty Meter Telescope," because it will have a primary mirror 30 meters in diameter.
Experts estimate the Thirty Meter Telescope will cost between $970 million and $1.2 billion to produce. This groundbreaking project will be supported by the United States and Canada, as well as other countries, such as Japan, China, and India.