I really enjoy Vesta because it’s so bright. From really dark skies, you can spot the asteroid without optical aid when it’s closest to Earth. Anywhere else, it’s easy with binoculars. And although it looks like a star even in a large telescope, it’s great to see Vesta creeping across the sky. The stars also move. But they are so far away that we can only detect their movement with the naked eye after thousands of years have passed. Asteroids are tethered to the sun just as securely as planets and drift against background stars from night to night.
Contributed / Stellarium
Earth and Vesta came closest on August 17 at 191.8 million kilometers (119.2 million miles) apart and came into opposition just five nights later. Opposition occurs when two planets, or an asteroid and a planet, line up next to each other on the same side of the sun. That is also when they are closest to the year. Vesta’s brightness varies depending on its distance from Earth. At its maximum brightness on the 17th, it shone at magnitude 5.8. Now, two weeks later, it is still bright at magnitude 6.
German astronomer Heinrich Olbers discovered Vesta from his home observatory in March 1807, just five years after he found his first asteroid, Pallas. As a gesture of thanks to Carl Friedrich Gauss, the German mathematician who calculated the orbit of Ceres, Olbers asked Gauss to name his new find. Gauss chose vest after the Roman goddess of hearth and hearth.
Contributed / Stellarium with additions by Bob King
You can warm your hands in Vesta’s home by first finding Saturn, which climbs high in the southeastern sky around 10:30 p.m. local time in late August (9:30 p.m. in mid-September). . She points the binoculars at the ringed planet and “walks” towards the asteroid using the stars as stepping stones. On the map above, I’ve marked one possible path, but feel free to connect the dots your way. That’s part of the joy of discovery in finding things in the night sky.
Contributed / Bob King
The planets and many asteroids, including Vesta, move around the sun in the same direction, from from west to east as seen from Earth. Vesta is heading West right now because the Earth is going through it. Remember, we travel faster because our planet is closer to the sun than the asteroid.
Around the opposition, the Earth circles Vesta. For a moment, she appears to move backwards in the same way that a slower car appears to move backwards when you pass it on the freeway. The car did not suddenly change direction; it only seems that way because we are driving the car faster.
Also, the slower Vesta appears to be moving backwards or forwards. retrograde while we pass it. In October, when we are well beyond the asteroid, it will return to its normal or prograduate movement to the east. The same thing happens when the Earth goes around Mars, Jupiter, Saturn, etc.
Why look at Vesta? First, it’s just cool to see an asteroid and see it move. Although nearly a million of these rocky bodies have been observed and cataloged, few are bright enough to be seen so easily with binoculars. You owe it to yourself to become familiar with a class of objects that you have often read about, but may never have seen with your own eyes.
Vesta is also special in another way. It is the only known rocky protoplanet. In the distant past it was hot enough to melt and form a metal-rich core and rocky mantle, similar to Earth and the other terrestrial planets. At one time, Vesta was almost spherical, but two massive impacts removed so much material from its south polar region that it is now more potato-like in shape. Some of that material landed (and continues to land!) on Earth in the form of meteorites.
To learn more about Vesta and browse an impressive collection of close-up photos taken by NASA’s Dawn spacecraft during its 14-month mission there in 2011-12, visit photojournal.jpl.nasa.gov/target/vesta? sort= ASC.
