TOI-700 e: Habitable Zone, 28-Day Year
Terrestrial around TOI-700
It is 0.95 times Earth's radius, closest in size to Venus. A year there lasts 27.81 days, on an orbit 3 times closer to its star than Mercury is to the Sun. Its equilibrium temperature is 270 K (derived from the star rather than measured), in the range where liquid water is possible. The host star TOI-700 runs at 3459 K with 0.41 times the Sun's mass.
Where this planet stands on each testable criterion
Orbits within the zone where liquid water could persist. Yes.
A measured mass, not just a radius. No.
A measured temperature rather than one derived from the star. No.
Any detection of an atmosphere. Not recorded in the archive.
TOI-700 from the inside out
Orbit
/
Planet
Radius
0.95 Earth radii
Equilibrium temperature
270 K (derived)
One year
27.81 days
Orbit radius
0.1340 AU
Host star
TOI-700 at 3459 K
Distance
102 light-years
Starlight blocked
0.043% at each transit
What the transit gives
The depth of the dip is the ratio of the two discs, so the radius follows.
The archive lists no measured equilibrium temperature for this planet. The 270 K quoted here is derived from the star's output and the orbital distance, assuming a third of the light is reflected. It is an estimate from two numbers, not an observation.
Everything known here comes from how much light went missing. That fixes the size and leaves the mass entirely open.
TOI-700 has 4 known planets. Multi-planet systems are where orbital dynamics can be measured rather than assumed.
Found by Transiting Exoplanet Survey Satellite (TESS) in 2023. TESS scans most of the sky in 27-day stretches, so it favours bright nearby stars and short orbits over the faint distant ones Kepler specialised in.
TOI-700 e sits in the habitable zone on the arithmetic alone. That says where \
it orbits, not what it is like. What would you want measured next before calling it promising?
