TOI-700 e is a relatively recent addition to Lisa Kaltenegger’s list, discovered in early 2023. It is the second Earth-sized planet found in the habitable zone of the same star as its sibling, TOI-700 d, located 101.4 light-years away.

Key Physical Characteristics

• Planet Type: Terrestrial (rocky) world.
• Size: It is nearly identical to Earth, with about 95% of Earth’s radius.
• Orbit: It completes one orbit every 28 Earth days.
• The Star: TOI-700 is a red dwarf star that is remarkably quiet and stable, which is rare for this type of star and a huge advantage for potential life.

Habitability & Environment

In Kaltenegger’s research, TOI-700 e is particularly interesting because it sits in the “optimistic” habitable zone:

• Location: It is positioned between the hotter inner planet “c” and the cooler outer planet “d.”
• Energy Intake: It receives about 1.27 times the starlight that Earth gets from the Sun. This makes it slightly warmer than Earth, potentially similar to a very young Venus or a “hot Earth.”
• Atmosphere: Because the star is so calm, scientists believe this planet could have successfully held onto its atmosphere for billions of years without it being stripped away by solar flares.

Scientific Significance

• A “Double” Opportunity: Having two Earth-sized planets in the same system (d and e) within the habitable zone is extremely rare. It allows scientists to compare how distance from the same star affects the climate of two very similar worlds.
• Benchmarking Habitability: It helps Kaltenegger and her team refine their climate models to see if clouds or specific atmospheric gases could keep a “warm” Earth from becoming a runaway greenhouse world.
• Observational Target: Since the star is bright and stable, TOI-700 e is a high-priority target for future telescopes to search for water vapor or oxygen.

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Published @ March 24, 2026 9:27 am