NASA's Dawn spacecraft has left the asteroid Vesta and began its long journey to the dwarf planet Ceres.

Dawn spacecraft was launched in 2007 and reached the orbit around the asteroid Vesta on July 15, 2011. The probe was sent in order to study the two celestial bodies - Vesta and Ceres - and understand the solar system's evolution. While Vesta is solar system's brightest asteroid, Ceres is the largest asteroid. After completing a 15-month study, Dawn left Vesta about 2:26 a.m. EDT and began its three-year trip to Ceres, reported NBCNews.com.

"As we respectfully say goodbye to Vesta and reflect on the amazing discoveries over the past year, we eagerly look forward to the next phase of our adventure at Ceres, where even more exciting discoveries await," Robert Mase, Dawn project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement, according to NBCNews.com.

Both the asteroids are so big in the asteroid belt between Mars and Jupiter and they comprise of rocks and soil, but did not develop into a full planet. Because of its size, Ceres is called as a dwarf planet.

Ever since it reached the orbit of the Vesta, Dawn probe has sent images of the asteroid, which looks like a punctured football. A BBC report noted that the asteroid's face looks like the football as a result of two impacts that removed rocks present on the southern pole of the asteroid.

Based on the images sent by Dawn, experts noticed that the Vesta had two big craters and an iron ore. Besides this, the probe has also relayed pictures of the mineral content and other geological features of its terrain.

While departing from the asteroid, Dawn took pictures of the northern pole of Vesta for the first time. The images showed mountains and craters present in the northern pole.

Dawn will be reaching the orbit of Ceres which is about 590 miles by 2015 as part of its mission to further study the evolution of solar system.  While Vesta had rocks and mountains, experts believe that Ceres will be completely different from Vesta with dusty surface. After reaching Ceres, Dawn will be the first probe to orbit two asteroids on a asteroid belt.