[填空题]There have been claims that warming on Mars and Pluto are proof that the recent warming on Earth is caused by an increase in solar activity, and not by greenhouses gases. But we can say with (47) that, even if Mars, Pluto or any other planets have warmed in recent years, it is not due to (48) in solar activity.
The Sun’s energy output has not increased since direct (49) began in 1978. If increased solar output really was (50) , we should be seeing warming on all the planets and their moons, not just Mars and Pluto.
Our solar system has eight planets, three dwarf planets and quite a few moons with at least a (51) atmosphere, and thus a climate of sorts. Their climates will be 52 by local factors such as orbital variations, changes in reflectance (反射率) and even (53) eruptions, so it would not be surprising if several planets and moons turn out to be warming at any one time.
However, given that a yea