Finding Invisible Worlds

Astronomers detect planets they cannot see directly by using complementary methods:

• Transit method — starlight dips when a planet crosses its star
• Radial velocity — the star wobbles from a planet's gravity
• Direct imaging — photographs taken by blocking the star's glare
• Microlensing — background starlight bent by an intervening planet

Each has blind spots, so combining them reveals far more worlds than any one alone. The field is now shifting from finding planets to characterizing them — and eventually determining whether any harbor life.