I rate science discoveries by the “wow” scale and I feel that this is at least a “double wow” discovery.
A second earth-like exoplanet has been discovered only four light years away (25 trillion miles), which is one of the closest star systems to earth. The planet is in an 11 day orbit around the red dwarf star, Proxima Centauri b. The mass of this planet is around 1.3 times that of earth and the planet appears to be rocky. Even though it is closer to its star than mercury is to the sun, the star is cool enough that the surface temperature of the planet would allow the presence of liquid water, that is, it lies in the “Goldilocks” region. The study of this planet is just beginning and of course there will be an intense search for the possible presence of alien life.
Incidentally, the Alpha Centauri system is the planned target of the “StarShot” project of Steven Hawking, Freeman Dyson and others which will involve large numbers of very small space craft (nano-crafts) that will be powered by meter-sized “LightSails” only a few hundred atoms thick driven by 100 gigawatt lasers on earth to 20% of the speed of light, allowing the 4.37 light years flight to be accomplished in 20 years. The data obtained would take 4 years to return to earth.
This initially has the appearance of insanity, but the list of experts is very impressive and the Director will be Pete Worden, the ex-director of Ames Research Laboratory.