Sample: Scientific Argument NAME ______Per______1. Based on the evidence, I believe that the lake _evaporated___. I believe this due to the evidence on card B, C and D 2. On Card B it states, “In the region where the lake is found, planetary geologists have not yet observed any summer temperatures low enough to freeze methane” This is important because This evidence refutes that the lake froze. If the temperature did not get low enough to freeze, it could not have frozen. The only other option would be that the lake evaporated 2. On Card D it states, “Summer days have more hours of sunlight. Therefore, more energy is transferred to the lake in summer than any other season. This is important because If energy is transferred into the lake, this will cause the temperature of the lake to rise. If the temperature rises, there will be more kinetic energy causing the molecules to move faster. With enough energy, evaporation can occur. With more sunlight in summer, there are more hours for the energy to enter into the lake than any other season.

2. On Card C it states, “Summer started in 2002, the lake was there in 2007, there was no lake in 2009, fall started in 2010. Seasons on Titan are just over 7 years long. This is important because Titan is cold, even in the summer, because it’s so far away from the Sun. Even though it’s cold, it is a very long summer. Summer started in 2002 and the lake was there in 2007. We know that there was energy entering the lake for at least 5 years.

Somewhere between 2007 and 2009 the lake disappeared. We know the lake disappeared in the summer, when it had the most sunlight and had received the most energy. We also know that there have never been temperatures cold enough to freeze methane during the summer.

3. What happened on the macro scale (what you can see) Include the year you saw it, when you didn’t and how liquid takes the shape of its container. On Earth, we have seen large bodies of water when looking down from pictures. We are comparing this to the large body of liquid we saw on Titan. We know that Titan did not have water, but had liquid methane. We know that liquid takes the shape of its container. We saw the shape in blue from our picture, so there must have been a hole or crater holding the liquid methane. We saw the methane in the picture in 2007. There was a blue shape with brown all around it. In the next picture in 2009, there was no blue shape, it was all brown.

4. What happened at the molecular level? (What you cannot see) Compare the lakes evaporation to the simulation (+ sign = energy in (sun), this causes the heat to rise, which changes to molecules FOM) In class we did a simulation. In the simulation, we hit the plus sign to add energy and the minus sign to take energy away. With enough energy added, the heat would rise. When the heat rose, it caused the molecules to move faster. As the heat continued to rise, the molecules had much more freedom of movement. The molecules started to bounce all around the square and had much more kinetic energy. If the molecules moved fast enough, they began to evaporate and turn into a gas. This is similar to what happened with the lake. Energy was added into the lake from the sunlight for at least 5 years. With the energy added, it would cause the temperature to rise. This would increase the molecules freedom of movement and allow the liquid methane to go through a phase change as it evaporated and turned from a liquid to a gas. Word Bank: Freedom of movement, evaporation, molecule, freezing, phase change, temperature, kinetic energy, energy (Underlined and used by you)