Why do cepheid variable stars pulsate? include the details about what is happening in the interiors of these stars.

Can someone me choose a broad topic and area of focus i am really doing this as a tally to see which one most people pick ok water pollution global warming endangered species atmosphere for the !

Compare the quantity in column a with the quantity in column b. pa p a is tangent to the circle at a. column a column b ap a p ax a x question 4 options: the two quantities are equal. the quantity in column a is greater. the relationship cannot be determined from the information given. the quantity in column b is greater.

Explain how earths tilt and revolution around the sun affects weather and climate