The asteroid's official name is "4 Vesta" because it was the fourth asteroid discovered, on March 29, 1807 by astronomer Heinrich Wilhelm Olbers, and is named after Vesta, the virgin goddess of home and hearth from Roman mythology. About the length of Arizona, Vesta is the second-most-massive object in the asteroid belt after the dwarf planet Ceres. The less-massive Pallas is slightly larger, making Vesta third in volume.

Vesta has a unique surface feature which scientists enjoyed peering into. Two enormous craters are striking, 310 mile (500 km) wide Rheasilvia, centered near the south pole, and 250 mi (400 km) wide Veneneia. Rheasilvia crater is younger and overlies the Veneneia crater. Its width is 95% of the mean diameter of Vesta and it is about 12 mi deep. Its central peak rises 12-16 miles and it's 100 miles wide, making it compete with Mars' Olympus Mons as the largest mountain the in solar system.

What happened to the one percent of Vesta that was propelled from its home during those impacts? The debris, ranging in size from sand and gravel to boulder and mountain, was ejected into space where it began its own journey through the solar system. Scientist believe that about 5 percent of all meteorites we find on Earth are a result of this ancient impact in deep space.


Dawn mapped the geology, composition, and cratering record of Vesta, and determines its rotation state. It determined Vesta's interior structure by measuring its mass and gravity field. Together, this data has elucidated the origin and evolution of the second most massive asteroid in the main asteroid belt. Dawn found a heavily cratered surface on Vesta, with a rough topography that is transitional between rough topography that is transitional between planets and asteroids. Two colossal impact basins were found in the southern hemisphere, whose impacts caused planet-encircling trough systems to form.

Vesta Topography Map

The Dawn mission confirmed that Vesta is the parent body of the HED meteorites, via it instruments: GRaND elemental composition, VIR mineralogy and FC color bands. Indeed, Dawn found that Vesta's gravity field is consistent with an iron core of the size predicated by HED-based differentiation models. Additionally, the mission confirmed that Vesta experienced pervasive, even global melting, implying that differentiation may be a common history for large planetesimals accreting very soon after the first solar system solids condensed, A1 was still abundant.

Surprisingly, pitted terrains and gullies were found in several young craters, interpreted as evidence of volatile releases and transient water flow. Vesta's composition is volatile-depleted, so these hydrated materials are likely exogenous.

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