NASA's Messenger became the first Earth spacecraft ever to successfully circle the closest planet to the sun, Mercury.

Launched in August 2004, Messenger took six-and-a-half years to cover around 4.9 billion miles before slipping into an elliptical orbit around the planet Mercury on Thursday evening.

Speaking on the topic, DLR Institute of Planetary Research's chief Tilman Spohn said, "We have just reached the most exciting part of the MESSENGER mission, flying the spacecraft to just about 200 kilometres above the surface of Mercury."

The Messenger is equipped with several high-tech instruments like the Mercury Atmospheric & Surface Composition Spectrometer (MASCS), an infrared spectrograph and an ultraviolet & visible light spectrometer to help researchers solve many secrets.

The spacecraft will capture 3D pictures of the surface of Mercury and will let scientists to probe the planet's magnetic environment, composition and tenuous atmosphere, along with other features.

Being the closest planet to the Sun, Mercury is the hottest planet in the solar system. Temperature during noon reaches 400 degree Celsius. Moving at a speed of 107,000 miles per hour, Mercury takes just 58.7 days to complete a circle around the Sun.