Our Nearest Planetary Systems and Some Thoughts

 

According to Space.com https://www.space.com/18090-alpha-centauri-nearest-star-system.html the closest star to Earth is a triple-star system called Alpha Centauri. A mainstay in science fiction for…a long time now!

A Hubble Space Telescope image of Alpha Centauri A (left) and Alpha Centauri B (right). (Image credit: ESA/NASA)

The two main stars are known as Alpha Centauri A and Alpha Centauri B and form what is known as a binary pair. They are “about” 4.35 light-years from Earth. The third star is called Proxima Centauri or Alpha Centauri C, and it is “about” 4.25 light-years from Earth which makes it the closest star after our own sun.

Alpha Centauri A and B are on average about 23 astronomical units from on another which is a little more than the distance between the sun and Uranus. The closest the two stars ever come to each other is 11 astronomical units and the two stars orbit a common center of gravity every 80 years.An astronomical unit is the average distance between Earth and the sun, which equals 92,955,807 miles or 149,597,870 kilometers.

Proxima Centauri is about one-fifth of a light-year or 13,000 AUs from the two other stars, a distance that makes some astronomers question whether it should even be considered part of the same system -don’t worry the astronomers will argue about that amongst themselves for decades. It is thought that Proxima Centauri may be passing through the system and will leave the vicinity in several million years, or it may be gravitationally bound to the binary pair. If it's bound, it has an orbital period around the other two stars of about 500,000 years.

To the naked eye Alpha Centauri A and B shine as one which makes them the third brightest "star" in our night sky. The two separate stars can be seen through a small telescope, making the system one of the finest binary stars that can be observed. Proxima Centauri is too faint to see unaided, and through a telescope it appears about four diameters of the full moon away from the other two.

Alpha Centauri A, which is also known as Rigel Kentaurus, is a yellow star of the same type (G2) which is what our own sun although slightly larger. It is three times closer to Earth than the next nearest star like our sun.

Alpha Centauri B is an orange K1-type star slightly smaller than the sun. Proxima Centauri is a red dwarf about one-eighth the size of our sun. The system is in the Southern sky and is not visible to observers above the latitude of 29 degrees north, a line that passes near Houston and Orlando, Fla. In the Southern Hemisphere, the Alpha Centauri system is easy to find because the cross-piece of the Southern Cross (from Delta to Beta Crucis) points the way. Its right ascension is 14h 39m 41s and its declination is minus 60 degrees 50 minutes 7 seconds.

People will always, or should, ask whether there are any planets in the system -after all we hear so much about far more distance systems with exo planets. Well, in August, 2016, astronomers announced that they had detected an Earth-size planet orbiting Proxima Centauri. The planet, known as Proxima b (they pulled all the stops out on deciding on that name), is about 1.3 times more massive than Earth, which suggests that the exo planet is a rocky world. And the fact that Proxima b is a relatively small distance from Earth makes it a particularly appealing target for scientists. The planet is also in the star's habitable zone that is just the right range of distances from a star where liquid water can exist on the surface of a body. Proxima b lies just 4.7 million miles (7.5 million km) from its host star and completes one orbit every 11.2 Earth-days.

On Nov. 14, 2018, astronomers announced the detection of a planet candidate circling Barnard's Star, which lies just 6 light-years from the sun. Only the three stars in the Alpha Centauri system, located about 4.3 light-years from us, are closer solar neighbors. Barnard's Star is a red dwarf about one-sixth as massive as Earth's sun and just 3 percent as luminous. Astronomers think Barnard's Star may be about 10 billion years old — twice as old as our sun.

Barnard's Star is so dim that things would get very cold out in the exo planet's neighborhood. Astronomers estimate Barnard's Star b's surface temperature at probably minus 275 degrees Fahrenheit (minus 170 degrees Celsius).  Barnard's Star b is about 3.2 times more massive than our home planet, making it a "super-Earth";  a class of world significantly larger than Earth but smaller than ice giants such as Neptune. Super-Earths are among the most common planets in the Milky Way, but we don't have any in our solar system.

If -if-  this exo planet ends up being confirmed, and that seems very likely, then Barnard's Star b still will not be the nearest exo-planet to Earth as that distinction goes to Proxima b..

It has to be remembered that these are only exo planets that we know of and there may be others in these systems. Inhabited planets? We have no idea but there are other systems "close" to our own and the question is always the same when you think about it logically.

The James Webb telescope cost $10 billion and looks out into deep space so far and we know that it is unlikely that we will ever get as far out as .5% of the distance viewed.

Hubble 'only' cost $2 billion.Why has no device been sent into space to more closely study our nearest neighbours?

Does that not make far more sense especially with SETI programs?

The 21st century has brought us mini yet very sophisticated satellites and Starlink consists of many satellites released in one go so why has no one bothered designing something similar -small probes heading out toward our nearest neighbours and able to send back images (we can send a satellite to follow another to film it smash into an asteroid after all) while at the same time trying to detect signals and broadcast a signal?

People, especially the debunkers who do no real research, keep stating the "vast inter-galactic distances involved in space travel and that this rules out alien (UFO) visitors. Carl Sagan stated that distance was the greatest problem.

Well, inter-galactically, yes. I agree but the nearest solar systems are always ignored. "WE cannot ravel that distance therefore no alien civilisation can!

We actually had the technology to get to the Moon. By now we should have sent a manned flight to Mars but we just could not be bothered whether for political or financial reasons while at the same time having military, weapon development and Black Budgets running into far more than the paltry $10 billion that the James Webb cost.

An alien civilisation may be far more interested in science than warfare and put all of its efforts into space and planetary exploration. Depending on the age of the civilisation its technology may make Proxima Centauri to Earth a "short side journey".

I doubt I will see it in my lifetime but if Bigelow is really that interested in finding alien life then he has the finances and ability to launch a program not looking for “dinobeavers” or chain-smoking werewolves.