Hello and welcome. I'm Jane Houston Jones at NASA's Jet Propulsion Laboratory in
Pasadena, California.
The early solar system was a messy place and asteroids, moons and planets
frequently collided. These collisions and impacts left scars we can see.
Craters are the most common surface features on many solid planets and moons.
When an impactor strikes the solid surface, a shock wave spreads out from the
impact site. The shock wave fractures the rock and excavates a large cavity,
much larger than the impactor.
The impact sprays material in all directions.
Sometimes the force of the impact is great enough to melt some of the local
rock.
If an impactor is large enough, some of the material pushed toward the edges of
the crater will slump back towards the center, and the rock beneath the crater
will rebound, or push back, creating a central peak in the crater.
The slumped edges of these craters also may create terraces that step down into
the crater.
We can even see crater chains on many moons and planets. These are thought to be
made by the impact of a string of objects, just like what happened when comet
Shoemaker-Levy 9 impacted Jupiter.
Most impact features on many of the moons and planets can't be seen by amateur
telescopes. You'll have to look at mission images for those.
When you're not looking at craters this month, turn your eyes toward Saturn.
You'll find it halfway up from the southern horizon at sunset.
The hours between midnight and dawn offer glimpses of Pluto, Uranus, Neptune and
even asteroid Vesta, which has a huge impact crater at its south pole.
A large family of meteorites which fell to Earth may have originated from this
impact event on Vesta.
We'll have more to say about NASA's Dawn spacecraft next month, when it's
expected to achieve orbit around Vesta.
There are two eclipses this month, too. A partial solar eclipse on June 1 is
visible over the northern Arctic regions. Two weeks later, on June 15, a total
lunar eclipse will be visible from much of the Southern Hemisphere.
You can read all about impacts in our solar system at solarsystem.nasa.gov/yss,
for Year of the Solar System.
And you can learn all about NASA's missions at www.nasa.gov.
That's all for this month. I'm Jane Houston Jones.
Документальный фильм "What's up for June? Solar system collisions!"
