This was found by a very large group led by an astronomer in England and also including astronomers all over the world. It was a combination of data and information -  all of the data taken at the European Southern Observatory in Chile because this is around Proxima Centauri which is in the southern skies so we can’t actually see it from here.



The planet is called Proxima B. Its around the star, Proxima Cantauri and then you get a letter designation.

It is about four and half light years so Prxima Centauri is the closest star to Earth besides the Sun but still really really far away. So, its the amount of time light can travel in about four and a quarter years.



It’s a neightbor, its in our backyard, just keeping track of how big out backyard it.

This was found using a couple of different telescopes using whats called the Radio Velocity Method. So, these planets are very dim. They’re next to stars which are very bright and so very rarely so you actually see them per say. You actually look for the wobble in the star caused by the planet. As it goes around the star, it tugs on it and it causes it to wobble back and forth. You use what’s called Doppler Shift to see a change in the frequency of the light.  That gives you a velocity so then you see in this case, a periodic wobbling. In this case, it was a period of eleven days.



This planet is a weird place compared to Earth. It’s got an eleven day year. It orbits Proxima Cantauri which is a much smaller, cooler, redder star.

We have a lower limit on the mass of the star but we don’t have an exact mass. We know it’s at least 1.3 Earth masses so its bigger than Earth but it could range up to 2.5 Earth masses. We also don’t know anything about its atmosphere. We are guessing it’s rocky but it could be gaseous. Because it’s not passing in front of the star, we can’t do Spectroscopy - where we look at the atmospheric signals in it. Basically, we sort of know its mass, we know its period, and we know characteristics of the star. What got people even more excited is that this falls in the so called “Habitable Zone” of the star - meaning theoretically, you could have liquid water on the surface and liquid water is required by all life.

That leads directly to the key point: It is in the “sweet spot” because the star is far less than one percent as bright as the Sun. The "sweet spot" for liquid water is much closer to the star, which is why you can be literally 20 times closer to its star than the Earth is to the Sun and still have the possibility for liquid water. However, yes, it could be habitable but it’s also very close to the star. Despite being small, the small stars - so called Red Dwarfs - are actually more active than say, a bigger star like the Sun. You get more solar flares, more X-rays coming out, more UV, more high energy particles, and the planet is much much closer so when you do get a so called Coronal Mass Ejection  - where it spits a bunch of high energy particles at the planet - you get hit harder. The end effect of this may be that you strip off the atmosphere completely and that you bath the surface in radiation dangerous to life, so it could be a really nasty place. The bottom line is, we don’t really know.

It is possible theoretically, but we are dealing with something that we have no analog for in our solar system. This is far closer to its parent star than Mercury is to our star. If you generated a strong enough Magnetic Field like the Earth has, it helps protect from particle radiation. This is really cool but we don’t really know the details and it will probably be a while before we do.

It can either be considered or not considered part of the Alpha Centauri System. Alpha Centauri - which looks like a very bright star in the southern sky - is actually two roughly Sun-like stars which are creatively named Alpha Cantauri A and B. Then you’ve got Proxima Cantauri - the small, dim, Red Dwarf - that sits much farther away and is probably gravitationally bound to the others. Rather than orbiting each other like A and B do every few years, it orbits in more like, half a million years. So, the effect is not that strong, other than they would see a couple of bright stars that are Alpha Centauri A and B.    

Part of the lesson is reminding us, even when we go to the closest star besides the Sun, we still find a planet and it’s kind of Earth-like. It’s an example in our own backyard, so to speak, that tells us that these things are probably really common out there, and that’s what we are finding. We have confirmed more than 3,000 planets around other stars. Some fraction of those are in the Earth-like Habitable Zone category. So its kind of amazing that we happen to find one of those around our closest neighbor.  

At current space craft speed, it would take tens of thousands of years to get a space craft there. There are people always pondering about using other technologies to get there faster, but best case, you’re talking about decades to get there. That’s why remote observations are by far, the most intriguing.

Yes, very much so. For reference, in 1995, we discovered the first planet around another star. This is a burgeoning, big developing field that you’re going to keep getting exciting discoveries from and keep learning more and more.