The concept of gravity was discovered by which famous physicist?

What is the hardest natural substance on Earth?

What is the softest substance on Earth?

Which famous British physicist wrote A Brief History of Time?

What was the name of the first man-made satellite launched by the Soviet Union in 1957?

Humans and chimpanzees share roughly how much DNA?

Which is the main gas that makes up the Earth's atmosphere?

The image formed in a compound microscope is

Where do auroras form