4 Vesta

4 Vesta is the brightest asteroid visible in the night sky, and the third-largest asteroid in the main belt. After the discoveries of Ceres and Pallas in 1801 and 1802 respectively, the German astronomer Heinrich Wilhelm Matthias Olbers hypothesized that more objects could be located in the region between the orbits of Mars and Jupiter, and on March 29, 1807 he discovered Vesta.

Vesta is named after the Roman goddess of hearth, home and family, and comprises almost 10% of the mass of the asteroid belt. Its most prominent feature is the Rheasilvia crater. 505 km in diameter, the Rheasilvia crater stretches across 90% the length of the asteroid, and is one of the largest in the Solar System. It was created less than a billion years ago in an impact that made Vesta lose an estimated 1% of its total mass. This event is also responsible for the creation of the howardite-eucrite-diogenite meteorites, which comprise 5% of all meteorite falls on Earth. These meteorites have provided a wealth of knowledge on the geology of Vesta.

Vesta is considered a surviving protoplanet, created during the formation of the Solar System. Even though the asteroid’s composition is differentiated indicating a geologically active past, it is not considered a dwarf planet due to the collision at the Rhesilvia crater that deformed its spherical shape.

On July 16th, 2011 the Dawn spacecraft entered orbit around Vesta for a 1 year exploration mission. Dawn left orbit on September 5th, 2012 en route for Ceres.

More info on 4 Vesta, the V-type asteroid, is available from our pervious post here…


Including the excellent primary research paper by Dr. Zoe Landsman, Chief Scientist at Exolith, the maker of fine quality Martian, Lunar, and Asteroidal regolith (sounds like an ad, but it’s not.)

As for me, I am doing what I always wanted to do (except be an astronaut). Re-constructing 3 weeks work in imaging 4 Vesta brought that all back for me. Last night it was +2C and the dew point hovered at -2C. For the two hours I needed it to hover. I was thinking I’d have it in my astropix. We see above, I did. I am sleepless. This is Astronomy. This is Science, I guess. I really appreciate it. Better than being behind a PC. Imaging a satellite on an asteroid, perhaps, as long as it was my idea; my work that would be good. Otherwise where is the thrill in that?

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