Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Very low density is the concentration of gas molecules in the mesosphere.
What is the concentration of gas molecules in the mesosphere?

You call egg-shaped galaxies, which are reddish to yellowish in color because they contain mostly old stars, elliptical galaxies.
What do you call egg-shaped galaxies, which are reddish to yellowish in color because they contain mostly old stars?

Higher type of temperatures increase the likelihood of fires.

What type of temperatures increase the likelihood of fires?