(dramatic music)
- [Narrator] They are nestled
in the final frontier,
countless worlds, scattered
throughout countless galaxies,
challenged the notion that
we are alone in the universe.
Exoplanets are worlds that exist
outside of our solar system.
Also known as Extrasolar planets,
these bodies often orbit their own stars,
with some being a part of
entire planetary systems.
Exoplanets are made of the same elements
as the world's and our solar system,
and based on their
composition and structures
are just as diverse.
Some, known as giant or
Neptune-like planets,
are large gaseous worlds.
Other gas giants called Hot Jupiters
closely orbit their stars
causing the planets to have
high surface temperatures.
Another category of exoplanets
consists of Super Earths.
Smaller than the gas giants
but larger than earth,
Super Earths are terrestrial
and made primarily of
rocky or icy material.
The final category includes Earth analogs.
Much as their name implies,
Earth Analogs are similar
to Earth in various ways,
including size, composition
and distance to their home star.
Exoplanets are difficult
to detect directly.
Mostly because they are out
shined by the stars they orbit.
To circumvent this, about
five primary methods
have been developed to find
these planetary bodies,
including radio velocity,
in which a planet
causes a star to wobble.
Direct imaging,
where the glare of stars is blocked
in order to see objects nearby.
Astrometry, which observes
the star's movements
in relation to nearby stars.
Gravitational microlensing,
which observes the light of a star
being dent by a planet's
gravitational pull.
And the most prolific form of
finding exoplanets, transit.
The method in which a planet passes
between its star and Earth,
thereby deeming its star's light.
Scientists have suspected
the existence of worlds
outside of our solar system
for thousands of years.
But the first confirmed
existence of an exoplanet
orbiting a sun-like star
only occurred in 1995.
Ever since, about 4000
exoplanets have been confirmed
by multiple discovery methods,
with about 3,000 more
awaiting verification.
According to one theory,
at least one exoplanet orbits
each star in the Milky Way.
This would place the exoplanet count
in our local galaxy to about one trillion.
The search for exoplanets continues,
not just to create a
catalog of known worlds,
but also to see if life
may exist elsewhere
in the universe.
Astrobiologists closely study the size,
composition, and location of exoplanets
relative to their stars
to see the likelihood of organisms
thriving in an environment
other than earth.
Who knows what discoveries
these new worlds could bring?
