Pick a common happening , develop an explanation for it , and describe an experiment you could perform to test your explanation.

Plant's produce oxygen, to explain this you would state that the plant uses CO2 from the air and removes the carbon and then release breathable O2 into the atmosphere. To test this you could use a small fern and put it in a sealed container of some kind big enough to hold it, then add a burning candle in the container with the plant, since we know fire burms O2 and creates CO2 the plant should use the CO2 and create more O2 keeping the fire from burning out from lack of oxygen

We can infer that star y is closer but other factors must be considered include the heat of the star, the mass, and the brightness of the star. even though star x seems dimmer it may just be less bright or contains less heat.