Wednesday, October 15, 2014

Adventures with Lea #6: Craters and Comets

   Now, this is NOT the big Adventure I've been planning, but more of a tiny fun one to tide you all over!  It's an adventure in learning!  Today in astronomy class, we did a fun experiment about comets and asteroid craters!  First, we did measurements of crater sizes to see the correlation of size and velocity to the diameter of the crater.  Or in my brain, we got to drop stuff in flour and make a mess for science!  Then, we made our own comet and smashed it to pieces to see the difference between a comet and an asteroid.  The experiment was actually very fun and very easy to do!
     So, for any of you budding scientist, science or astronomy teachers, or parents who want to impress their kids with a weird experiment, here's what to do!  Quick word, the second experiment requires dry ice and ammonia so you have to be able to get some of that.  You can learn more about dry ice, dry ice safety, and where to get it here.  Ammonia can be purchased at basically any store with a cleaning isle I think so....ya!

Experiment #1:  Ball Bearing Asteroids and Cosmic Craters!  

  • 2 (or more!) Ball Bearings of different sizes
  • A meter stick
  • A ruler
  • Flour in a Tupperware tub
  • A wooden block or other large, solid and semi heavy block
  • A fro-pick or other comb of choice
  • A flashlight
  • A magnet
  • Something to put the flour tub on to stop it from making a mess such as a folder, newspaper, table mat, whatever you want.
  • A really tall person (or a chair to stand on if you're short like meeeee)

Step 1:  Open the tub of flour and press it nice and tightly together with the block of wood.  The amount of flour doesn't really matte, as long as there are a few inches for the bearings to go through.  Once you've pressed it nice and tight, there should be some left over floofy edges.  Use the comb to spread the floofy flour over the compressed flour to make a little cloud-like layer above the hard, compressed stuff.  Finally, smooth it out so there are no lines in the flour.

Step 2:  Place the tub on the clean-surface-thingy of choice and set it either on the table or on the floor.  My group put it on the floor because it was easier to do higher heights without having to stand on tables. 

Step 3:  Measure 50 cm from the top of the flour and drop the smallest ball bearing.  Use the magnet to suck the ball bearing out of its crater without touching it and measure the little crater with the ruler.  It might be easiest to see the full crater by shining the flashlight on it at an angle.  You can also see how deep the craters are when looking from the side rather than straight on, which is cooler.  Here's a handy dandy chart to use!  You can of course make it bigger for the number of ball bearings you use and the heights you use!

Crater Diameter
Small Ball
Crater Diameter
Large Ball
Impact velocity



Step 4: Smooth it back over and repeat the process for the larger ball bearings.  You might need to stand on a chair to do the higher heights sooooo have fun with that!

Step 5:  If you like doing math, find the Impact Velocity and make a scatter plot of your findings with the Impact Velocity as the X axis and the Diameter of the crater as the Y axis.  I suggest using different colors for each ball.  The impact velocity can be found by v = (2ay)^1/2 where a is the acceleration of gravity, 9.8 m/s^2, and y is the height from which you dropped the ball.  For example, if y = 3 meters, then v = (2 × 9.8 × 3)^1/2, or v = (58.8)^1/2 = 7.7 m/s.

Step 6:  Keep doing it for funzies and then clean up!  Yaaaaaaay.

Experiment #2: Make Your Own Comet!!!!!

  • 2 Spoonfuls of sand
  • 1 Cup of water
  • About 2 tablespoons of ammonia 
  • Potting soil 
  • 1 cup of crushed dry ice
  • A large plastic bag (like a Ziploc baggie)
  • A long wooden spoon for stirring (one you're o with getting really dirty and gross)
  • A bucket or bowl or other thingy
  • Gloves
Step 1:  Use a freezer bag to line the bottom of your bucket.  I suggest having at least 3 people so 1 can hold the bucket, 1 can stir, and one can add things and later hold the comet into shape.

Step 2:  Pour 1 cup of water in the bag.

Step 3:  Add 2 spoonfuls of sand, stirring well. Be careful not to rip the bag by stirring too hard!

Step 4:  Add a dash of ammonia.  I say about 2 tablespoons or a quick pour is fine.  It should start to smell pretty terribly so don't hold it close to your face.

Step 5:  Add a dash of organic material (potting soil). Stir until well-mixed.

Step 6:  This step is tricky so read carefully:  Place a block or chunk of dry ice inside a towel and crush the block with a mallet and add 1 cup of crushed dry ice to the bag, while stirring vigorously.  It's going to burst up in a cloud of gas, so be careful and don't like, stick your head in it.  Stir very very fast for about 15 seconds then remove the spoon and go to the next step immediately

Step 7: Lift the comet out of the bucket using the plastic liner and shape it for a few
seconds as if you were building a snowball (use gloves!).  Be careful not to squeeze it so stuff comes jutting out the top.  You just want to cup your hands around it and just hold that for about 5 minutes.  It's going to sizzle and make horrifying sounds at you like a dying monter lobster, but just ignore it and don't let go.

Step 8: Unwrap the comet once it is frozen enough to hold its shape.  You should get something like this!  Ours looks like a human heart which is a little creepy....  Shining the light on it alos makes the more crystalline parts glisten which is cool!

Step 9:  Finally, you can smash it!  Pretend you are a giant inter-stellar space monster hurling a comet at a defenseless planet like a boss and crush it to pieces on the pavement outside!  This teaches people that comets are less terrifying that asteroids because rocks are more dense or something like that.  It taught me how to feel like a boss soooooooooooooo SCIENCE!!!!

Hope everyone enjoyed this little science guide to some fun experiments where you get to make a mess!  Have a nice daaaay!!!