Dawn is fast approaching!
That's the NASA Dawn probe to the asteroids Vesta and Ceres with it's first stop at the brightest asteroid Vesta. At present, it's about 100,000 kms from Vesta and closing fast for it's July 16 rendezvous! At last, I and the rest of humanity are going to get an up-close-and-personal view of one of the asteroid belt's biggest denizens, rather than just a dot of light in the eyepiece of a telescope!
Not that we don't know what asteroids look like. In fact, about a dozen asteroids have either had close-up encounters with Earth-based technology or, at the very least, been viewed from a distance by them. Near Earth objects Eros and Itokawa have even been orbited by them. But Vesta is a unique one. It's a remnant of a remarkable time in the solar system's history when the planetary gallery resembled something more like a raucous rave party than the stately gathering we have today.
Imagine back about 4.3 billion years ago. The solar nebula had collapsed and bodies from the size of peas to objects as big and bigger than the planets we have today were still settling into their orbits. Indeed, many astronomers suspect we had many times the planets we have now, all jostling for position. The worlds of our current solar system were simply the winners of a titanic battle of bulk, gravity, time and even dumb luck!
Some of that "raw material" remains in the form of asteroids and comets. So getting a close look at these tiny bits of cosmic flotsam could give us profound insights into the early history and evolution of our solar system.
Vesta and Ceres represent the largest members of this population of bits and pieces. They're big enough that mass and gravity have acted to turn them into roughly spherical shapes. However, they're still too small to be considered planets, giving astronomers a challenge to understand them in the grand scheme of the solar system.
As Dawn has approached Vesta, the image of this 500 kilometer-sized body has swelled in size and detail. And the amount of detail they will gather will be even further increased by the fact that, over the next year, Dawn will orbit Vesta before departing for an encounter with even larger "protoplanet" Ceres.
For myself, Vesta holds a special place in my heart as the first asteroid I've ever caught sight of. They're difficult objects to spot and track and finding one gives one an appreciation for the challenge of discovery they represent. They are tiny dots of light that move slowly against the background stars. Hard to believe that, at one time, they were considered "vermin" of the solar system, introducing unwelcome streaks to long-duration photos of objects.
Now, they represent one of the greatest mysteries of modern science - how the solar system came to be.
So tune in, folks. With the approach of Dawn comes a whole new day of astronomical discovery!