To solve this question, the user needs to have knowledge about the history of science and the inventions made by Galileo.

Option A: Barometer - This option is incorrect as the barometer was invented by Evangelista Torricelli, not Galileo.

Option B: Pendulum clock - This option is incorrect as the pendulum clock was invented by Christiaan Huygens, not Galileo.

Option C: Microscope - This option is incorrect as the microscope was invented by Antonie van Leeuwenhoek, not Galileo.

Option D: Thermometer - This option is partially correct. Galileo did not invent the thermometer, but he did invent a type of thermometer called the thermoscope, which could indicate changes in temperature but did not have a scale to measure it. Later, others developed the thermometer with a scale.

Therefore, the correct answer is:

The Answer is: D