NASA announced on Tuesday the discovery of a new, Earth-sized planet orbiting its stars' optimistic habitable zone. Scientists say liquid water could be present at some point in the planet's history. The planet, T-O-I-700-E, is part of the T-O-I-700 system, and is roughly 95% the size of Earth. It likely has a rocky surface, according to NASA. Three other planets were previously discovered in the T-O-I-700-E, is also in the habitable zone. NASA said this is one of only a few systems with multiple, small habitable, zone planets that they know of. T-O-I-700 takes 28 days to orbit its star, a small red dwarf star located around 100 light, years from Earth. The planets have all been discovered by NASA's Transiting Exoplanet Survey Satellite, or TAS.