As of June of 2014, no astronauts have walked on the surface of the planet Mars. All of the space missions to Mars have been carried out by unmanned spacecraft. More »

Two people who stood up for what they believed in were Abraham Lincoln and Martin Luther King Jr. Both men came from modest beginnings and worked their way into the public eye while fearlessly speaking out on what they b... More »

The two-wheeled self-balancing electric scooter that can be stood on is called the Segway PT. The computers and motors of the scooter are located within the base of the vehicle, which help keep it upright when it is movi... More » Vehicles

Mars earned its famous moniker, "red planet," due to its red appearance that is highly visible from Earth. The distinct rusty-red color of Mars is attributed to the abundance of iron-rich soil that covers the planet's su... More »

Mars is the second smallest planet in the solar system, with a diameter of just over 4,212 miles and a circumference of 13,256 miles. Its diameter is about 53 percent that of the Earth. Among the major planets, only Merc... More »

Mars is the fourth planet from the sun. Its average distance from the sun is 141,633,120 miles, approximately 1.5 times that of Earth. More »

Because Mars with its famous red coloration is readily visible from Earth, it is unknown who first discovered it; NASA lists the planet as "known by the ancients." There are records of its existence as far back as ancien... More » Science Astronomy Planets