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TRAPPIST-1e

An Earth-sized world in a compact seven-planet system.

classification
Terrestrial exoplanet
system
TRAPPIST-1
overview //

TRAPPIST-1e is one of seven roughly Earth-sized planets transiting a small, cool red dwarf. It orbits within the range of distances where a suitable atmosphere could allow surface liquid water.

technical data //
Distance from Earth
about 40 light years
Radius
about 0.92 Earth radii
Mass
about 0.69 Earth masses
Orbital period
6.10 days
Orbital distance
about 0.029 AU from its star

Only values with an established scientific consensus are listed. Where a quantity is uncertain or model-dependent, it is discussed in the sections below rather than stated as data.

what we know //
01

Seven planets transit the same star

Repeated, regularly spaced dips in the star's brightness identify seven planets, several close to Earth in size.

02

The planets tug on each other

Transits arrive slightly early or late as the planets interact gravitationally, which yields their masses and densities.

03

The host star is small and active

TRAPPIST-1 is an ultracool dwarf that emits frequent flares — a significant factor for any atmosphere.

how do we know? //

Transit photometry

Ground and space telescopes measured the periodic brightness dips that reveal planet sizes and orbits.

Transit-timing variations

Small deviations in transit times encode the planets' mutual gravitational pulls, and therefore their masses.

Infrared spectroscopy

JWST is testing whether these planets retain atmospheres at all.

methods archive →
open questions //
  • Does TRAPPIST-1e have an atmosphere?This is not yet established.
  • Could stellar flares have stripped the inner planets' atmospheres over time?
  • Is surface liquid water possible here?Only a hypothesis, dependent on an atmosphere we have not confirmed.

Items above are unresolved. Hypotheses are labelled as such and are not presented as confirmed findings.

related missions //
continue exploring //