Saturday, March 29, 2014

Kids Astronomy: Planets Part 2

Moving out into the outer solar system, we come to Jupiter, king of the planets. What do you get when you add very massive planet plus close to an asteroid belt?  In this case, 62 moons!

At at 100 times the size of Earth, you would think a Jovian day would be very long. Nope.  A day on Jupiter lasts a mere 10 hours.

That super fast spin generates incredible winds and super storms, like the Great Red Spot, a hurricane that is larger than the entire Earth and has been going on for at least 400 years.

Choclo is using our tornado tube with orange water and red glitter to demonstrate the storm.
 All the gas giants have rings, but none are as well known as Saturn's.  I used more powder and salt to demonstrate the dust and ice which form those rings.  I then had a lab assistant drag pencils (eraser side down) across it to show how Saturn's moons "shepherd" the rings into distinct sections.

As a kid, I was told that the gas giants had no surface below all that atmosphere, that they were gas all the way through.  This made no sense to me.  Wouldn't the mass of the planet crush the gas into a solid, or at least a liquid?

The actual answer seems to be yes, at least for Jupiter and Saturn.  But there is still no "surface." It is now believed that the gases are compressed so gradually, that there is no definite point where the atmosphere stops being gas and starts being liquid.

 Next up, the mysterious (and hard to pronounce) Uranus.  Firstly, we don't know why it spins on it's side, but it gives it really strange seasons.

We used the globe and flashlight trick again, and it's worth ding just to see this for yourself.

During winter, half of the entire planet gets no sun for 21 years. During summer (21 years) the sun does not set.  In spring and fall, they get something more like our days and nights.

Weirder than that, scientists think there is a surface under Uranus's atmosphere.  One theory is that the surface is very cold and covered with large diamonds.  Another theory holds that the surface is a very hot (5000 degree) ocean.

So, anyone want to go and find out?

That leaves Neptune as the last of the true planets.  It's like Uranus, only smaller, and with faster winds.  Neptune has a large, long lasting hurricane called The Great Dark Spot, and a white cloud (very helpful when measuring rotation) which astronomers call "Scooter" for the speed with which it scoots around the planet.

What about Pluto?  Two interesting things about our distant dwarf planet.

Did you know that they keep finding new moons of Pluto? Right now it's up to four, with a possible fifth awaiting verification. Not bad considering Pluto is much smaller than our own moon!

Also, its one of many Kuiper belt object (also called Trans Neptuniam Objects).

The Kuiper belt is like a second asteroid belt after Neptune, except the "asteroids" are larger, farther apart, and their orbits are a little bit tilted from the rest of the planets' orbits.

Past the Kuiper belt, you have the Oort cloud.  This is  a remenant  of the cloud of dust and gas the solar system formed from, and it is the very outer fringe of the solar system.

It's so far away from the sun, that the sun's gravity holds objects here very weakly.  Any passing object can affect trajectories here, sometimes sending chunks of ice and dust spinning towards the inner solar system.

We call these comets!  And here is how to make one.

Line a bowl with a trash bag.
Pour in 2 cups of water.
Add a few spoons of sand or dirt.
Add a splash of ammonia.
Add some simple sugars (dark corn syrup or molasses)
Stir, then add 1 cups of crushed dry ice.
Wearing gloves (!) form the freezing mess into a snowball by pressing on the outside of the trash bag.

Dump it out, and there you have it!

Of course, to be a real comet, you'd have to shoot it into space, but if you'd rather keep it here, you can make your own "solar wind" by blowing on it.  The dry ice generates a fine "tail" and the whole "dirty snowball" eventually disintegrates into a lacy ball of ice in very much the way a real comet does.

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