Extreme & Unusual Objects
Extreme Exoplanets
Astronomers have found planets in environments that look nothing like the Solar System.
Extreme is relative: these are unusual by our standards, and they show the range of what planets can be.
- Observe
Planets with orbits and temperatures unlike our own.
- Measure
Transits, radial velocity and spectroscopy.
- Model
Atmospheric and orbital models tested against unusual planets.
- Explain
Planetary systems are far more varied than ours.
What is it?
Most known exoplanets are unlike anything in our Solar System. Surveys are biased toward large, close-in planets, which is one reason the extremes are so prominent in the catalog.
Observations of these worlds test what we know about how planets form, migrate and lose their atmospheres.
How does it happen?
- Stage 1Planet forms in a disk
- Stage 2Orbit changes over timeMigration or interactions
- Stage 3Star heats or erodes it
- Stage 4Astronomers detect unusual properties
What do we actually observe?
- Ultra-hot Jupiters
- Gas giants orbiting in days. KELT-9b has a dayside temperature around 4,000 kelvin or more, hotter than many stars. WASP-12b is stretched by tides and its orbit is shrinking.
- Lava worlds
- Rocky planets so close to their stars that their surfaces may be molten, such as 55 Cancri e, though the details of its atmosphere are still debated.
- Highly eccentric orbits
- HD 80606b has an orbit so elongated that it heats up dramatically as it swings close to its star.
- Evaporating planets
- Some planets lose atmosphere or material to their star's radiation and wind, forming comet-like tails, as seen with GJ 436b and the disintegrating planet KIC 12557548b.
- Unusual stars
- Planets orbit pulsars (the first exoplanets confirmed, in 1992), two stars at once (Kepler-16b), a white dwarf (WD 1856+534 b) and the small red dwarf TRAPPIST-1, which hosts seven.
How do scientists detect it?
- Transit surveys. Kepler and TESS.
- Spectroscopy. JWST and Hubble study atmospheres and escaping gas.
- Radial velocity. Measures masses and eccentricity.
Why does it matter?
- They show the diversity of planetary systems.
- They test theories of planet formation, migration and atmospheric loss.
The SpaceWeatherTracker connection
A star's flares, wind and radiation can heat and erode nearby planets. SpaceWeatherTracker follows the same process around the Sun, where it is far gentler.
Related phenomena
Primary family: Extreme & Unusual Objects
Extreme Exoplanets: common questions
What is an ultra-hot Jupiter?
A gas giant so close to its star that its dayside temperature exceeds about 2,000 degrees Celsius.
Do these planets show what most planets are like?
Not necessarily. Detection methods favor large, close-in planets, so extremes are over-represented.