Q & A

Q: What element is most plentiful on the Sun?
A: Hydrogen. The Sun is made up of about 75% hydrogen and 25% helium. About 0.1% is metals (made from hydrogen via nuclear fusion). This ratio is changing over time (very slowly), as the nuclear reactions continue, converting smaller atoms into more massive ones.

Q & A

Q: Why can't we see gravity?
A: First of all, we can only see the light that is reflected from things (we don't see the thing itself), and gravity doesn't reflect light. Gravitational lensing, however, is the displacement of light due to the warping of space by a gravitational lens (a massive object in space that bends light that passes by it, due to the gravitational forces). This is a way that gravity can be "seen."