“Vesta”的概念、定义、翻译、参考文献-科学参考

Vesta

Astronomy

Asteroid 4, the fourth asteroid to be discovered, by H. W. M. Olbers in 1807. Its mean diameter is 525 km, similar to that of Pallas. Vesta’s mass is 3 × 10²⁰ kg and its mean density is 3.9 g/cm³. Its orbit has a semimajor axis of 2.36 au, period 3.63 years, perihelion 2.15 au, aphelion 2.57 au, and inclination of 7°.1. Vesta’s colour changes slightly as it rotates every 5.34 hours, indicating that its surface is not uniform in composition. The average albedo is 0.42. Vesta’s spectrum is characteristic of the mineral pyroxene, common in lava flows. It is sufficiently different from most other asteroids to be assigned a special classification, V-type (for Vesta). Vesta may be a source of the howardite, eucrite, and diogenite (HED) meteorites along with some other small asteroids. Its apparent mean magnitude at opposition is 6.5, but at particularly favourable oppositions it can reach magnitude 5.5, the only asteroid bright enough to be visible with the naked eye. NASA’s Dawn spacecraft orbited it for 14 months, between 2011 July and 2012 September. Dawn’s observations showed that the original south polar region of Vesta has been almost completely removed by one or two large ancient impacts, leaving a basin 450 km across called Rheasilvia. Debris ejected by these impacts presumably became the V-type asteroids and HED meteorites.

Space Exploration

The second-largest asteroid in the Solar System, 530 km in diameter, discovered in 1807 by German astronomer Heinrich Olbers. Vesta orbits the Sun at a distance of 353 million km, with a period (time taken to circle the Sun) of 3.63 years. It is the brightest asteroid in the night sky and becomes visible without a telescope. Vesta has a shallow crater at its south pole, indicating that a large chunk of rock has been dislodged at some point.
In 2007, the spacecraft Dawn took off on a mission to study Vesta and the dwarf planet Ceres. The first spacecraft to visit Vesta and Ceres, it entered Vesta’s orbit in July 2011 and completed a 14-month survey mission. It went on to Ceres, entering orbit in March 2015 to take close-up images of a pair of bright spots on the dwarf planet.

Geology and Earth Sciences

The third largest (after Ceres and Pallas) solar system asteroid (No. 4), diameter 526 km; approximate mass 3 × 10²⁰ kg; rotational period 5.342 hours; orbital period 3.63 years. It was imaged in 1995 by the Hubble Space Telescope and appears to have a basaltic crust overlying an olivine mantle, indicating that differentiation has occurred. In 2007, the spacecraft Dawn took off on a mission to study Vesta and Ceres. The first spacecraft to do so, it entered Vesta’s orbit in July 2011 and completed a 14-month survey mission. It went on to Ceres, entering orbit in March 2015.

单词	Vesta
释义	Vesta Astronomy Asteroid 4, the fourth asteroid to be discovered, by H. W. M. Olbers in 1807. Its mean diameter is 525 km, similar to that of Pallas. Vesta’s mass is 3 × 10²⁰ kg and its mean density is 3.9 g/cm³. Its orbit has a semimajor axis of 2.36 au, period 3.63 years, perihelion 2.15 au, aphelion 2.57 au, and inclination of 7°.1. Vesta’s colour changes slightly as it rotates every 5.34 hours, indicating that its surface is not uniform in composition. The average albedo is 0.42. Vesta’s spectrum is characteristic of the mineral pyroxene, common in lava flows. It is sufficiently different from most other asteroids to be assigned a special classification, V-type (for Vesta). Vesta may be a source of the howardite, eucrite, and diogenite (HED) meteorites along with some other small asteroids. Its apparent mean magnitude at opposition is 6.5, but at particularly favourable oppositions it can reach magnitude 5.5, the only asteroid bright enough to be visible with the naked eye. NASA’s Dawn spacecraft orbited it for 14 months, between 2011 July and 2012 September. Dawn’s observations showed that the original south polar region of Vesta has been almost completely removed by one or two large ancient impacts, leaving a basin 450 km across called Rheasilvia. Debris ejected by these impacts presumably became the V-type asteroids and HED meteorites. Space Exploration The second-largest asteroid in the Solar System, 530 km in diameter, discovered in 1807 by German astronomer Heinrich Olbers. Vesta orbits the Sun at a distance of 353 million km, with a period (time taken to circle the Sun) of 3.63 years. It is the brightest asteroid in the night sky and becomes visible without a telescope. Vesta has a shallow crater at its south pole, indicating that a large chunk of rock has been dislodged at some point. In 2007, the spacecraft Dawn took off on a mission to study Vesta and the dwarf planet Ceres. The first spacecraft to visit Vesta and Ceres, it entered Vesta’s orbit in July 2011 and completed a 14-month survey mission. It went on to Ceres, entering orbit in March 2015 to take close-up images of a pair of bright spots on the dwarf planet. Geology and Earth Sciences The third largest (after Ceres and Pallas) solar system asteroid (No. 4), diameter 526 km; approximate mass 3 × 10²⁰ kg; rotational period 5.342 hours; orbital period 3.63 years. It was imaged in 1995 by the Hubble Space Telescope and appears to have a basaltic crust overlying an olivine mantle, indicating that differentiation has occurred. In 2007, the spacecraft Dawn took off on a mission to study Vesta and Ceres. The first spacecraft to do so, it entered Vesta’s orbit in July 2011 and completed a 14-month survey mission. It went on to Ceres, entering orbit in March 2015.
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