Space
What Are Exoplanets?
Exoplanets orbit stars beyond the Sun and are usually detected through transits, stellar motion, or direct imaging rather than by unaided sight.
Space
Travel from the Moon and Mars to distant stars and black holes.
Space
Why Does the Moon Have Phases?
The Moon is always half illuminated by the Sun; phases occur because its orbit lets us see changing fractions of that sunlit half.
Space
Could Humans Ever Travel to Another Star?
Interstellar travel is consistent with known physics but extraordinarily difficult because even the nearest stars are several light-years away.
Space
What Happens When a Star Dies?
A star's final state depends mainly on its mass: many leave white dwarfs, while massive stars may explode and leave neutron stars or black holes.
Space
How Big Is the Universe?
The observable universe is about 93 billion light-years across because space expanded while ancient light travelled, while the entire universe may be much larger.
Space
What Would It Be Like to Live on Mars?
Living on Mars would require sealed, radiation-shielded habitats with oxygen, water recycling, food, power, thermal control, and reliable life support.