It will grow little by little while you sleep, from nothing but a cloud of cosmic dust.
Collect it by completing a challenge to shut off your alarm.
If you try to snooze or don't shut the alarm off in time, your star will explode destroying your night's work.
Stars you make are automatically chained together to build constellations which unlock sweet rewards, but careful, a supernova will destroy a chain.
Your star can play calming, ambient sounds while it grows to help you fall asleep.