Why is the sky blue? The earth is surrounded by an atmosphere. ... How much does the earth weigh? ...
How far away is the sun? ...
What is a black hole? ...
How do airplanes fly? ...
How do flies walk on the ceiling? ...
How are rainbows made? ...
Are sharks mammals?

•The earth weighs-5.972 × 10^24 kg
•The sun is 94.079 million miles away
•A black hole is a region of spacetime where gravity is so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it.
•Airplanes fly because they are able to generate a force called Lift which normally moves the airplane upward. Lift is generated by the forward motion of the airplane through the air. This motion is produced by the Thrust of the engine.
•Flies need sticky feet to walk on ceilings, but not so sticky that they get stuck upside down. So each foot comes with a pair of claws that help hoist the gooey foot off the wall. Flies use several different techniques to get unstuck: pushing, twisting, and peeling its footpads free
•rainbows are made by the refraction of light particles
•sharks are not mammals since they are cold blooded