On the largest moon of Saturn, the hills are named after hobbits and elves, and the lakes after lakes on Earth. Titan is, in many ways, the most Earth-like world we’ve ever found.
Titan is a bitterly cold world covered in an orange haze. At around 180 degrees Celsius below zero, Titan is far too cold for liquid water. But beneath the smog lie rivers, lakes and seas, full of liquid ethane and methane. At home, methane is used for gas cooking. On Titan, methane seems to cycle from lakes to clouds like water does on Earth.
The spacecraft Cassini and the Huygens probe arrived at Saturn on 30 June 2004, ten years ago on Monday. In those ten years, Cassini has made over 100 flybys of Saturn’s moons. The most recent one bounced radio waves off Titan’s lakes. In April, it zoomed close enough to ‘sniff’ Titan’s atmosphere and take a chemical sample.
Last month, scientists looked at sunsets on Titan and found the orange smog affects blue light more than red light. This technique could help us understand planets beyond our solar system, the exoplanets. By watching an exoplanet as it moves between its star and Earth, scientists could learn about its alien atmosphere.
Late last year, scientists found the sea floor of Titan’s second largest sea, Ligeia Mare. Radar was able to pass through the pure liquid in the sea and bounce off the bottom. It turns out Ligeia Mare is 170 metres deep. That’s the same depth as Tasmania’s Lake St Clair, the deepest freshwater lake in Australia.
On Sunday, scientists shared a new study. Cassini’s radar had recorded a bright area in Ligeia Mare which later disappeared. Scientists think the bright area could have been a passing feature, like a wave, rising bubbles or something floating on the methane.
Perhaps this is a glimpse of the lake waking from a long winter. Seasons move slowly on Saturn’s moon. Titan’s northern hemisphere had its spring equinox in August 2009, and the summer solstice is not until May 2017.
Label chocolates as protons, neutrons and electrons.
Make pancake batter.
Make two small pancakes.
Make one large pancake. Put pancakes on plates to cool.
A decorated hydrogen pancake, with one proton and one electron.
A decorated oxygen pancake, with eight protons and eight neutrons. Two electrons are in the inner circle and four electrons are spread out in the outer circle.
Give oxygen two more electrons in the top and right positions of the outer ring to make two electron pairs and two unpaired electrons.
To make water, move the small pancakes (hydrogen atoms) to line up with the unpaired electrons in the big pancake (oxygen).
Safety: This activity uses a hot stove to cook pancakes. Children should ask an adult for help. For more information, go to the Double Helix safety page.
You will need
1 cup self-raising flour
1 cup milk
1 egg
Bowl
Spoon
Frying pan
Stove
Butter
Spatula
3 plates
10 round pieces of dark chocolate in a bowl marked ‘Protons’
8 round pieces of white chocolate in a bowl marked ‘Neutrons’
10 M&M’s (all same colour) in a bowl marked ‘Electrons’
Chocolate sauce (we used Ice Magic)
A toothpick
What to do
Add the flour, egg and milk into the bowl and stir well to make pancake batter.
Put the frying pan on the stove and heat it up to a high setting. Add a bit of butter to the frying pan.
Once the butter is melted, add pancake batter to the frying pan to make two circles. Cook the pancakes on both sides until light brown, and put them on separate plates.
Add more pancake batter to the frying pan to make one big circle. Cook the pancake on both sides and put it on the third plate.
Leave the pancakes to cool.
Let’s decorate! To turn a small pancake into a hydrogen atom, we need to give it one proton and one electron. Stick one dark chocolate proton in the middle of the pancake.
The electron orbits the proton. Use the chocolate sauce and the toothpick to make a wavy circle on the pancake. It's easier if the chocolate sauce is in a squeezy bottle and you squeeze dots around the pancake and connect them to each other with the toothpick.
Add one M&M somewhere on the wavy circle.
Repeat steps 6 to 8 for the second small pancake.
To turn the big pancake into an oxygen atom, it needs eight protons, eight neutrons and eight electrons. The protons and neutrons are in the middle. Stick eight dark chocolate protons and eight white chocolate neutrons into the middle of the big pancake.
Use chocolate sauce to draw a wavy circle around the chocolate pieces, and then make a second wavy circle around the outside of the first circle.
The first circle, close to the chocolate pieces, contains two electrons. When electrons pair up like this, they must spin in opposite directions. Put two M&M’s next to each other on the inside wavy circle, so one M&M has the M facing up, and the other M&M has the M facing down.
The second circle, on the outside, contains six electrons. To start with, put four M&M’s on the outside wavy circle in the top, bottom, left and right positions.
There are two M&M’s left. Add them next to the top and right M&M’s on the big pancake, so they make electron pairs. Make sure each pair has one M&M with the M facing up and the other with the M facing down. Oxygen now has two electron pairs and two unpaired electrons.
You have two hydrogen atoms and an oxygen atom, so let’s put them together to make H2O, water.
Move the small pancakes so the M&M’s line up with the unpaired M&M’s on the bottom and left of the big pancake. The hydrogen and oxygen atoms share these electrons, and all the electrons are now in pairs!
What’s happening?
This model shows that protons and neutrons are found in the middle of an atom, and electrons are on the outside. The protons and neutrons are about the same size and weight, and electrons are smaller. Chemical reactions involve electrons, which can be swapped or shared.
This model isn’t perfect. For one thing, atoms are 3D and our model is flat. Also, the electrons are much too big and placed much too close to the protons. Electrons are actually really far away from protons. If your chocolate proton is two centimetres wide, you would need to walk for an hour to get far enough away to put down the M&M electron for hydrogen. That’s a big pancake!
Applications
Atoms are too small to see. Making models and drawing pictures can help us understand them. Chemists use computer models to look at atoms and explore how chemical reactions happen. It can be award-winning science! The 2013 Nobel Prize in Chemistry went to three chemists who designed a way for computers to model chemical reactions.
Hippos are considered to be a) herbivores, but they have been filmed occasionally eating dead animals.
Earth and Uranus are not named after Roman gods.
A solid which drops out of solution is called a precipitate.
Gravity is multiplied by mass to find weight.
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