Sun (or Sol)

DISTANCE 0.00 light years

MASS 1.00

LUMINOSITY 1.0

AGE 4.5 billion years

A typical yellow dwarf (spectral type G2) with a diameter of 1,392,530km. The Sun has a family of nine planets (or eight if we exclude Pluto), the third of which supports life.

Proxima and Alpha Centauri

DISTANCE 4.24 (Proxima) to 4.36 light years

MASS A: 1.09 B: 0.89 C: 0.11

LUMINOSITY A: 1.519 B: 0.5002 C: 0.00006

RADIUS A: 1.22 B: 0.86 C: 0.154

SURFACE TEMPERATURE A: 5,753 K B: 5,242 C: 2,883 K

AGE A: 5.2 billion years B: 5.3 billion years C: 4.85 billion years

Our nearest stellar neighbour (apart from the Sun) is a triple star system consisting of a red dwarf called Proxima Centauri orbiting two sun-like stars - Alpha Centauri A and B.

Alpha Centauri A has a spectral type of G2, which means it has the same temperature and colour as our Sun. The only difference is its luminosity: with a mass 1.09 times that of our Sun, Alpha Centauri A emits a steady 54 per cent more light than our Sun. In fact, of all the nearest stars within 12 light years of where we live, Alpha Centauri A is the one that resembles the Sun the most.

Alpha Centauri B is an orange-yellow star of spectral type K1, which makes it cooler and smaller than the Sun. With a mass of only 0.88, Alpha Centauri B has a stable brightness of 44 per cent of the standard solar value of our Sun.

The two stars orbit each other every 79.91 years and are separated by at least 11 astronomical units (i.e. Sun-Saturn distance) and a maximum of 35 astronomical units (i.e. Sun-Neptune) at their farthest point.

In 1986, scientists from Yale University, USA - Pierre Demarque, D.B. Guenther and William van Altena - used the most recent data on the luminosity and mass of the Alpha Centauri system to estimate the age of the stellar system. Calculations suggest that both Alpha Centauri A and B are about 5 billion years old - more than enough time for intelligence to arise on a habitable planet.

As of 2024, no planetary system has been detected around these sun-like stars. The biggest problem astronomers have in detecting planets in our neighbouring star system, despite its proximity to our Sun, is the brightness of the stars, and the way both stars already wobble from side-to-side quite significantly as they move together through space due to the gravitational pull of both stars on each other, making it extremely difficult to detect the tiniest of wobbles in the stars' motions from much smaller bodies we call planets. But this does not mean there could be no planets. A mathematical study of this stellar system suggests that stable planetary orbits should exist around both stars to a distance of at least 2 astronomical units. Since the Sun's fourth planet, Mars, is only 1.5 astronomical units, it is likely that there is at least one (and possibly two) Earth-like planet lurking in the Alpha Centauri system, but again there is no direct evidence for this. Only a spacecraft venturing out to this star system will answer the question (unless life on a habitable planet in this system decides to come and visit us first, which is more likely given the age of these stars).

The only evidence we do have for the likely existence of unseen planets comes from a careful spectroscopic analysis of the chemical composition of stars: For life and technology to arise on a planet, there must be elements heavier than those found in a typical star. For example, we need silicon and oxygen to form rocks; carbon, nitrogen and oxygen to develop life; and iron, titanium, uranium, and other metals to create a technology. In our Sun, there is a residue of about two per cent of such heavy elements. In the case of Alpha Centauri A and B, the residue of heavy elements is much greater than in our Sun! (1). Everything is leaning towards the existence of at least two planetary systems.

The closest star to our Sun at present is a very faint red dwarf called Proxima Centauri (spectral type M5). It is of the 'flare-up' variety, meaning that it emits great bursts of energy from time-to-time. It orbits the other two larger luminous spheres at a distance of about 13,000 astronomical units (430 times the Sun-Neptune distance) and takes millions of years to complete an orbit.

On 24 August 2016, observations made of Proxima Centauri using a telescope in Chile has revealed a hidden companion roughly 1.2 times the mass of the Earth and in an 11-day orbit around the red dwarf. Moreover, its estimated distance from the star suggests that liquid water could be present. The only complicating factor in this liquid water debate is the distance from the star: the planet is quite close to the red dwarf. This means that the star's flares at different times can easily and violently increase the wind speed in the alien atmosphere, heating the surface to high levels. If water could somehow remain on the surface, primitive alien life will almost certainly exist. But if not, the critters will have to be well-protected deep beneath an ocean of water and/or in caves. However, if temperatures exceed a critical level, the surface is likely to be barren and dry, and so reduce the chances of finding life. And, like Mercury in our solar system, the alien world is locked in its revolutions so that one side of the planet will always face the red dwarf. On the other side, it will be perpetually dark and possibly cold.

If we want to find highly advanced alien life, the kind with which we could communicate with and have technology, we would be better off making the extra effort to visit Alpha Centauri A and B. Here, the likelihood of finding planets around these stars are extremely high. We should not be surprised if a small rocky planet will have similar Earth-like conditions orbiting at least one of these yellowish Sun-like stars.

Or, the only other possibility of finding intelligent life around Proxima Centauri is if an advanced extraterrestrial civilization could be having reconnaissance trips to the red dwarf and planet and returning to the other two stars. The question is, can scientists detect anything near Proxima Centauri to support this kind of technological activity?

During 30 hours of observations of Proxima Centauri between April and May 2019 and reported on 18 December 2020 (2), astronomers involved in the Breakthrough Listen project (3) had apparently detected an anomalous signal using the Parkes Radio Telescope. The signal was recorded for prosperity and it lasted long enough for scientists to detect a subtle shift in its frequency of around 982.002MHz. More interestingly, the Doppler shift of the signal increased over the period of observation (i.e., it was moving towards us) and moved in the opposite direction to what would be expected from the Earth's spin, as if implying a non-terrestrial origin for the signal. It is as if the source of the signal were moving in a circle of about 16 arcminutes (approximately 1/4 of a degree, or half the angular width of the Earth's Moon) in angular diameter. The only inconsistency in this observation is that the movement of the signal's source to produce the Doppler shift is not the same as the movement of the hidden planet around the red dwarf. It seems the hidden object, perhaps a smaller moon moving around the planet, had been moving independently. But then again, scientists cannot disprove the signal could be from a technology orbiting the planet.

This observation was repeated in December 2020. Unfortunately the signal disappeared too quickly, preventing the scientists from officially confirming the "technosignature" of the signal. Otherwise, there was nothing in the content of the signal that could be construed as coming from an intelligent alien civilisation. As Andrew Siemion of the University of California, Berkeley, said:

"BLC1 is, for all intents and purposes, just a tone, just one note. It has absolutely no additional features that we can discern at this point." (4)

About the closest thing to describing it as "technological" is how narrow the beam was. Scientists who have examined the signal have been unable to identify an alternative natural emitter capable of achieving such an unusually narrow beam. As Siemion said:

"We don't know of any natural way to compress electromagnetic energy into a single bin in frequency. Perhaps, some as-yet-unknown exotic quirk of plasma physics could be a natural explanation for the tantalizingly concentrated radio waves. But for the moment, the only source that we know of is technological.

It [the signal] has some particular properties that caused it to pass many of our checks, and we cannot yet explain it." (5)

When the signal, known as BLC1 (stands for Breakthrough Listen Candidate 1), was first detected, astronomers from another observatory happened to be studying Proxima Centauri within about 10 days of the emergence of the BLC1 signal. They noted in their paper "a bright, long-duration optical flare, accompanied by a series of intense, coherent radio bursts". Of course, these bursts are not part of the BLC1 signal. The main reason for bringing up this other observation is to discount or significantly reduce the chances of any native and potentially technical life developing natively on the planet around the red dwarf (6). Given how particularly intense this optical flare event was, another study in February 2021 has looked at the probability of extraterrestrial life living on the planet near this red dwarf and concluded that the chances were extremely small, on the order of 10^-8 (7). But what the study does not rule out is the possibility of technical life from another star system visiting and/or leaving the planet and having emitted briefly the technosignature from an alien spacecraft.

To reduce the chances of finibng alien life around the triple star system, on 25 October 2021, researchers published further work on the BLC1 signal. In the absence of a repeating signal in the direction of this red dwarf, which could help rule-out any possible man-made origin of the signal, the researchers have concluded that the signal was probably from human radio interference. As Jason Wright, a SETI-centric astronomer at Penn State University in Pennsylvania noted:

"If you see such a signal and it’s not coming from the surface of Earth, you know you have detected extraterrestrial technology. Unfortunately, humans have launched a lot of extraterrestrial technology." (8)

Sounds like it might be time to start cleaning up Earth's orbit of its thousands of artificial satellites. Like light pollution from artificial lights on Earth that can interfere with the quality work of astronomers using their optical telescopes, the same might be needed for artificial satellites in Earth's orbit. Reducing their numbers would help immensely to improve the odds of detecting alien radio signals in space. Or else it is time we build a spacecraft to take us to the stars.

As for alien life around the other two Sun-like stars, there is nothing the scientists have to prove planets, and extraterrestrial life, do not exist. Since Alpha Centauri A and B are older than our Sun and have more of the heavier elements needed to build rocky planets and technology, it wouldn't be surprising if an advanced alien civilization already exists and is venturing out into space to conduct its own scientific work as we speak. Who knows? Perhaps an artificial space station orbiting a moon or smaller undetected planet in Proxima Centauri had decided to send a narrow beam signal in our direction. Or was it another smaller spacecraft that had visited the red dwarf and, as it accelerated away from the scene and the impending doom of the solar flare, had emitted some radiation in our direction as part of its propulsion technology? Perhaps it was nothing more than a rescue mission to pick up alien scientists who were studying the red dwarf or on the hidden planet and realized their predicament as the star was preparing for the next major outburst. Or maybe the aliens had gathered all the data they needed, and made a quick turn around and escape from the red dwarf, only to direct some of its radiation emissions in our direction?

More of a reason why humans should visit this star system, and should be the first and primary destination for any journey to the stars. Stop mucking around with searching for radio signals in space or looking for alien bacteria. And don't worry about red dwarfs and their planets. Alpha Centauri A and B remain the best bet for finding alien life, and most likely highly technically-advanced. Time to look at what it would take to physically venture out to the stars.

There is one more interesting snippet of information that could be relevant to the search for alien life on Alpha Centauri. It concerns the UFO case of Antonio Villas Boas. A fascinating and highly detailed case which did not require hypnosis, but contained a wealth of information about how aliens go about their activities in space and why they are here. The case includes hand sketches of the UFO to help those open-minded scientists (especially those looking to be challenged by what's on offer in the world of electromagnetism) who are seriously considering investigating close-range UFOs allegedly seen by witnesses.

According to Antonio, the Brazilian farmer and student claimed he was abducted in 1957, examined by a group of aliens, had sex with a female alien, and was later allowed to leave the UFO and observe its departure. According to Antonio's observations, the UFO returned to the sky in a southerly direction. And prior to the departure, the female alien turned around for the last time to face Antonio and communicated with her hand and finger at her belly and them pointed to the sky in a direction that Antonio was certain it was to the south. Unless the UFO had some other part of our solar system to investigate, it seems altogether likely that carrying of important biological samples from Antonio would probably necessitate a quick and safe return to its home planet for careful analysis, not to mention the likelihood that an impregnated female alien might need to be well looked after throughout the term of her pregnancy. As the UFO itself is not considered to be a particularly lightweight design, with its three large external protrusions at the rear that glowed red when accelerating, two small side planks or winglets (possibly designed to control the side tilting of the object), and a rudder-like protrusion at the front (for turning left or right), not to mention how many aliens were involved in the abduction operation (and hence the additional mass being carried at high speeds to reach our planet), it is likely that the UFO originated from a close-range star system capable of harboring life. But just how close could we be talking about here?

As the only Sun-like star(s) capable of harboring an Earth-like planet within 12 light years of our Sun in the southern hemisphere is Alpha Centauri (all other potential ET homes in this range are in our northern hemisphere), it is important to be prepared for the possibility of a quiet and hidden alien civilization with a native home located in the Alpha Centauri A and B star system.