In the constellation, Aquarius 39 light years away is one of the most important exoplanets system discovered so far, Trappist one. The solar system has not just one earth-like planet but seven and four of them are in the habitable zone of the star.
The discovery was announced on 22 February 2017. The planets were detected using the transit method as they pass in front of their sun it is possible to measure a recurring decrease in sunlight over time. The planets are very small and the star is bright so it is a very tiny amount of light we are talking about. The scientist was using very advanced instruments to make the discovery. Spitzer Space Telescope and the Very Large Telescope was amongst the telescopes used. The light is filtered around the atmosphere of the planet and the molecules will make the light shift in color. That will give information about the composition of the planets.
Trappist one is a very small brown dwarf just slightly larger than Jupiter but much more massive. The planetary system could also in size be compared with the moon system of Jupiter. The planets are very close to each other. All the planets are orbiting closer there sun than Mercurius and the planets will sometime look larger than the moon and the sky of their neighbor planet. Perhaps aliens of Trappist 1 d is colonizing Trappist 1 e if they have the same technology in space travel like us.
As the planets are rotating near its sun there are in a tidally locked orbit with one face pointing toward the sun all the time. It is daylight all the time on one side and night all the time on the other.
The gravitational interaction between the planets is significant. On the time the first planet complete eight revolutions around the sun the second complete five, and the third three, and the fourth two. Their orbits are resonant
Trappist-1b is in the same size of earth but is very similar to Venus with a very thick atmosphere and it is very hot at the surface.
Trappist-1c the heaviest planet in the system and is also very similar to Venus. It is a rocky planet with a thick atmosphere and too hot for life.
Trappist-1d is the planet that has the largest ESI value amongst the exoplanets. The planet has also a high SPH index, which means that it likely to have vegetation. The planet has a thin atmosphere. It could be enough to keep the climate stable as the planet not rotating around its axis. The planet has about 250 times more water than earth.
Trappist-1e is also very similar to earth it could have liquid water. The zone between day and night is suitable for life. If the planet has enough atmosphere a larger part of the planet can be habitable.
Trappist-1f same size as the earth but not as dense. The planet has much water but in a gaseous state. The planet is likely not habitable.
Trappist-1g both radius and mass similar to earth and a stable climate. Water has been detected. The planet is cooler than earth but could be habitable.
Trappist-1h the smallest planet in the system with a size between mars and earth. Could contain water and has a temperature similar to the south pole. The planet is outside the habitable zone of the star.