Co-author Amaury Triaud notes that the star in this system is an "ultracool dwarf", and he clarifies what this means in relation to the planets: "The energy output from dwarf stars like TRAPPIST-1 is much weaker than that of our Sun".
The system of planets is located 40 light-years (235 trillion miles) from Earth and they lie in the Aquarius constellation.
The boffins at Nasa have discovered three habitable planets in a newly discovered solar system a mere 39 light years away from Earth.
Dr Copperwheat, from Liverpool John Moores University, said: "The discovery of multiple rocky planets with surface temperatures which allow for liquid water make this fantastic system an exciting future target in the search for life".
NASA has taken a momentous step forward in their quest to find life-sustaining planets outside our solar system, revealing the discovery of seven Earth-sized planets orbiting the same star.
Because the TRAPPIST-1 is so small, the planets are packed in very close togetherr.
The finding, published Wednesday in the journal Nature, follows the team's discovery in May of three Earth-sized planets orbiting the dwarf star, called TRAPPER-1. Unlike our own planet, one side of the TRAPPIST-1 planets could be submerged in perpetual night while the other sees never-ending light.
The US space agency said it will hold a news conference to present the findings at the agency's headquarters in Washington on Wednesday, February 22. One reason for the interest in exoplanets is the potential for some of them to support life. According to scientists, all seven planets could have liquid water, which is the key ingredient for life. They determined that the two closest planets completed an orbit about once every two days.
The more we know about outer space, the more we realize how less we have known.
Approximately 44 exoplanets have been discovered to be Earth size or with potentially habitable conditions, according to the University of Puerto Rico Planetary Habitability Laboratory.