Planets in Process

People who study how humans grow up have it easy -- they can watch children and see how their bodies and minds develop over time. Scientists who study planets and stars, on the other hand, just don't live long enough to watch the evolution of objects that exist for millions of years. Instead they tend to spot a young star in one direction of the sky, an older one somewhere else, and develop theories on how one kind of star can grow into the other. But sometimes, nearby, there are processes that space scientists actually can watch.

The wakes made  in Saturn's ring,
by gravity from the moon Prometheus.

Current theories say our early solar system was one big disk of dust and debris.  Over time, the material coalesced into all the planets, moons and asteroids we see today.  NASA’s Cassini spacecraft has been watching almost the exact same process happen in Saturn's beautiful rings, where the icy particles collect into giant snowballs every time the moon Prometheus swings by.

The gravitational pull of the moon sloshes ring material around, creating wakes like a speed boat cutting through the water. As the wake of debris pushes out, it triggers the formation of icy objects as large as 12 miles in diameter. Such a snowball is so big that it would cover the entire island of Manhattan and extend well east and west. But what's most exciting is that this is the first time scientists have been able to actively watch any kind of planetary object form, says Carl Murray, a Cassini team member based at Queen Mary, University of London.

Let's face it -- sometimes it's hard to believe that, as big as our Earth is, it was formed from nothing but a whole lot of space dust. But watching how dust can cling together to build something 12 miles long can help explain just how it's done. And if it can grow to that size, it can keep growing bigger. . . and bigger. . . and bigger. . . to the size of moons and planets.

Mind-Bogglingly Big. . .

"Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space"

--The Hitchhiker's Guide to the Galaxy by Douglas Adams

In The Hitchhiker's Guide to the Galaxy, Douglas Adams says you can blow someone's mind just by showing them how big the universe is -- and how small they are in comparison.  In real life, most of us can't ever quite grasp the sheer enormity of the universe.  It's even hard for those who study it regularly.  An astronomer recently told me: "You don't ever really get your head around it. You just kind of get used to it."

The vast size of the universe is one reason why it's so neat to think that each of us is made of parts that were made when the universe was born -- see, we're not so insignificant after all.  We're made of the very stuff that all the galaxies and stars are made of too.

But, it's still true that we're crazy small when compared to the whole thing.  Just to give you an idea of how mind bogglingly big the universe is, here's a few numbers:

One Astronomical Unit (or AU) = the distance to the sun, which is 93,000,000 miles away.

One Parsec (or pc) = the distance to the nearest star, which is 206,265 Astronomical Units.

The distance to the center of our galaxy, the Milky Way, is 8000 parsecs.

The distance to a nearby galaxy, Andromeda galaxy, is 100 times that distance.

And the distance to the edge of the observable universe is 5000 times the distance to Andromeda. . .

So what does that equal? How many miles away is the edge of the universe? Write me a comment and let me know what number you come up with!

We're the Non-Fiction Monday book this week!

Anastasia Suen teaches writing to all ages, and uses "Picture Books to Teach the Six Traits of Writing."

She offers the following writing suggestion at her page: 

Older Than the Stars by Karen C. Fox (Author) and Nancy Davis (Illustrator), is the Big Bang theory told as a cumulative rhyme. (Facts on each page explain the event in more detail.)

This is the BANG
when the world began.

Ideas Mini-lesson
Primary/Intermediate: Ask students to write a response to the ideas in this book. What did they think about being “older than the stars?” Use the Idea Rake graphic organizer before writing.

The Children's Book Council

Older Than the Stars was added to The Children's Book Council's reading list!

This is the Bang!

Download the cover image
Download the The Timeline of the Universe poster (11x17)

Welcome to the AstroBlog

This is the place
where Karen Fox
will tell the story
of the building blocks
that created the bang
from which the world sprang.