Nola Taylor Tillman

A do-it-yourself Galilean telescope makes an excellent and inexpensive starter telescope — or science fair project.

Reference Albert Einstein's theory of general relativity is based on the idea that massive objects cause a distortion in space-time, which is felt as gravity.

Reference The wormhole theory postulates that a theoretical passage through space-time could create shortcuts for long journeys across the universe.

Reference The Andromeda galaxy is the most distant object in the sky that you can see with your unaided eye. It's also on a collision course with our Milky Way.

Reference A red giant star is a dying star in the last stages of stellar evolution. Our own sun will turn into a red giant, expand and engulf the inner planets — including Earth.

Reference NASA is the United States space agency and was founded in 1958 to do human and robotic exploration of the solar system and to study the universe as well.

Reference Sir Isaac Newton invented calculus and explained optics. His most significant work involved forces and the development of a universal law of gravity.

Reference The largest known star in the universe is UY Scuti, a hypergiant with a radius around 1,700 times larger than the sun.

Reference We are living in a golden age of Milky Way research and exploration.

Reference Olympus Mons rises 16 miles above the Martian surface, making it the solar system's tallest volcano.

reference Most stars are main sequence stars that fuse hydrogen to form helium in their cores - including our sun.

Reference White dwarfs are hot, dense remnants of stars. They are the last observable stage of evolution for low and medium-mass stars including our sun.

Reference Cosmology by definition is the branch of astronomy involving the origin and evolution of the universe, from the Big Bang to the future of the cosmos.

Reference This list of famous astronomers includes great scientists in history who mastered many fields and modern astronomers who helped popularize astronomy.

Reference This gas giant is the largest planet in the solar system, but just how big is Jupiter?

Reference The temperature of Uranus averages minus 320 degrees Fahrenheit. Uranus holds the record for the coldest temperature ever measured in the solar system.

Reference The temperature on Mars doesn't get much above 70 degrees F and it drop down to nearly minus 200 degrees F, making it a relatively cold planet.

Since its 1990 launch, the Hubble Space Telescope has provided countless amazing images and contributed to many big discoveries. Learn more here.

Reference How big is the moon? Our moon is the fifth largest moon in the solar system, with a radius of 1,079.6 miles (1,737.5 kilometers).

Reference Based on what we can observe, the universe appears to be almost 28 billion light-years in diameter. However, it is far larger than that.