Exoplanets: Worlds Beyond Our Solar System

Thousands of planets orbiting distant stars - some might harbor life

The Exoplanet Revolution

🪐
5000+
Confirmed Exoplanets
🔭
Thousands of planets orbiting distant stars, including potentially habitable worlds

🌍Potentially Habitable Worlds

These planets orbit in the "habitable zone" where liquid water could exist - the key ingredient for life as we know it.

Proxima Centauri b

4.24 light-years
Type:Super-Earth
Star:Proxima Centauri (red dwarf)
Discovered:2016
Orbital Period:11.2 days

In habitable zone, but stellar flares may be problematic

Water
High
Atmosphere
Uncertain due to stellar activity
Closest known exoplanet to Earth

TRAPPIST-1e

40 light-years
Type:Rocky Earth-sized
Star:TRAPPIST-1 (ultra-cool dwarf)
Discovered:2017
Orbital Period:6.1 days

Best candidate in TRAPPIST-1 system

Water
Very High
Atmosphere
Being studied by JWST
Part of 7-planet system, 3 in habitable zone

Kepler-442b

1,206 light-years
Type:Super-Earth
Star:K-type main sequence
Discovered:2015
Orbital Period:112.3 days

61% chance of being in habitable zone

Water
High
Atmosphere
Likely, needs confirmation
High Earth Similarity Index (0.84)

Kepler-452b

1,400 light-years
Type:Super-Earth
Star:G-type (Sun-like)
Discovered:2015
Orbital Period:385 days

Earth's 'older cousin'

Water
High
Atmosphere
Possibly thick atmosphere
Orbits Sun-like star in habitable zone

LHS 1140 b

40 light-years
Type:Super-Earth or mini-Neptune
Star:M-dwarf (red dwarf)
Discovered:2017
Orbital Period:24.7 days

One of the best candidates for atmospheric studies

Water
Very High - may be ocean world
Atmosphere
Top target for JWST atmospheric studies
Transits a quiet red dwarf, ideal for observation

TOI-700 d

101 light-years
Type:Earth-sized
Star:M-dwarf
Discovered:2020
Orbital Period:37.4 days

In conservative habitable zone

Water
Moderate to High
Atmosphere
Under study
TESS mission's first Earth-sized planet in habitable zone

K2-18 b

124 light-years
Type:Mini-Neptune
Star:M-dwarf
Discovered:2015
Orbital Period:33 days

Water vapor detected in atmosphere (2019)

Water
Confirmed water vapor
Atmosphere
Confirmed - hydrogen-rich atmosphere with water
First exoplanet with water vapor in habitable zone

Kepler-186f

582 light-years
Type:Earth-sized
Star:M-dwarf
Discovered:2014
Orbital Period:130 days

First Earth-sized planet in habitable zone

Water
Moderate
Atmosphere
Unknown - too distant for current spectroscopy
Historic first Earth-sized habitable zone planet

🌪️Exotic & Extreme Worlds

HD 189733 b

Hot Jupiter
Glass rain sideways at 8,700 km/h

Deep blue color due to silicate particles in atmosphere that scatter blue light. Winds exceed 2 km/s.

🌡️ 1,000°C

PSR B1620-26 b

Ancient planet
13 billion years old

Oldest known planet, formed when universe was only 1 billion years old. Orbits a binary star system in globular cluster M4.

TrES-2b

Dark planet
Darkest planet known

Reflects less than 1% of light that hits it - darker than coal. Hot Jupiter with temperature of 980°C.

HD 106906 b

Rogue giant
11x Jupiter's mass, 738 AU from star

Orbits 650 AU from its star on a highly inclined, eccentric orbit. May help explain Planet Nine theories.

Kepler-16b

Circumbinary planet
Real-life Tatooine

Orbits two stars, like Star Wars' Tatooine. Saturn-sized gas giant in a circumbinary orbit.

KELT-9b

Ultra-hot Jupiter
Hottest known planet

Day side temperature exceeds 4,000°C - hotter than some stars. Molecules break apart into atoms.

🌡️ 4,300°C

GJ 504 b

Pink planet
Magenta colored gas giant

Glows magenta due to infrared heat from its formation. 4x Jupiter's mass, only 160 million years old.

HAT-P-7b

Corundum clouds
Rains rubies and sapphires

Atmospheric conditions allow corundum (rubies/sapphires) to condense and fall as 'rain'.

Types of Exoplanets

Hot Jupiters

Gas giants orbiting very close to their stars

Characteristics: Scorching temperatures, fast orbits, tidally locked
Examples:
51 Pegasi bHD 209458 bWASP-12b

Super-Earths

Rocky planets larger than Earth but smaller than Neptune

Characteristics: 1.5-2x Earth's size, potentially habitable
Examples:
Proxima Centauri bLHS 1140 bTOI-700 d

Ocean Worlds

Planets potentially covered entirely in liquid water

Characteristics: Deep global oceans, possibly habitable
Examples:
K2-18bTOI-1452 b

Lava Planets

Rocky worlds so hot their surfaces are molten

Characteristics: Extreme temperatures, one side always facing star
Examples:
55 Cancri eCoRoT-7bK2-141b

How We Find Exoplanets

Transit Method

Detects dip in star's brightness when planet passes in front

Advantages:

Can determine planet size and orbital period

Limitations:

Requires precise alignment

📊 ~75% of known exoplanets

Radial Velocity (Doppler)

Detects star's wobble caused by planet's gravity

Advantages:

Can determine planet mass

Limitations:

Better for large, close-in planets

📊 ~20% of known exoplanets

Direct Imaging

Photographs planets directly

Advantages:

Can study planet's atmosphere and orbit

Limitations:

Only works for large planets far from bright stars

📊 ~1% of known exoplanets

Gravitational Microlensing

Planet's gravity bends light from background star

Advantages:

Can detect distant planets and free-floating planets

Limitations:

Events are unrepeatable and brief

📊 ~100+ exoplanets

Historic Milestones

1992
First exoplanets discovered
PSR B1257+12 - planets around a pulsar
1995
First planet around Sun-like star
51 Pegasi b discovered, launching exoplanet revolution
2009
Kepler Space Telescope launched
Discovered 2,662 confirmed exoplanets
2014
First Earth-sized planet in habitable zone
Kepler-186f discovered
2017
TRAPPIST-1 system discovered
7 Earth-sized planets, 3 in habitable zone
2019
Water vapor in habitable zone
K2-18 b shows water vapor in atmosphere
2021
JWST begins observations
Revolutionary atmospheric characterization capability
2023
5,000+ exoplanets confirmed
New discoveries accelerating with improved technology

🔮 Future of Exoplanet Discovery

J W S T

Studying exoplanet atmospheres in unprecedented detail

R O M A N T E L E S C O P E

Will discover thousands more exoplanets via microlensing (launch 2027)

A R I E L

ESA mission to study exoplanet atmospheres (launch 2029)

P L A T O

Will search for Earth-like planets around Sun-like stars (launch 2026)

H A B I T A B L E W O R L D S O B S E R V A T O R Y

NASA concept to directly image Earth-like exoplanets

The Search Continues

Every day we discover new worlds orbiting distant stars. Some might have conditions suitable for life. The James Webb Space Telescope is now studying their atmospheres in unprecedented detail, searching for signs of life beyond Earth. We may be on the verge of answering humanity's oldest question: Are we alone?

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