All Questions

The retina

The iris

A substance that increases the rate of a chemical reaction without being consumed overall by the reaction

An atom of the same element with the same number of protons but a different number of neutrons

Charged particles from the Sun interacting with Earth's magnetic field and upper atmosphere

An object or region where gravity is so strong that not even light can escape from within its event horizon

A massive, luminous sphere of hot gas/plasma held together by gravity

The Milky Way

The streak of light produced when a meteoroid enters an atmosphere and heats up

A dwarf planet

Neptune

Uranus