There is a trick question most elementary students know when it comes to the mysteries of the universe – namely, what is the closest star to Earth?
It is, of course, the sun, also known as “Sol,” from the Latin for “Solis.”
For the record, the International Astronomical Union (IAU), which since 1922 has been responsible for naming celestial bodies, seemingly never officially sanctioned a name for our sun, but it does suggest we use the uppercase “Sun” contrary to the AP Stylebook.
As for the closest star to Earth that isn’t actually our sun, the distinction goes to Alpha Centauri, a triple star system in the southern constellation of Centaurus.
This is where it gets a bit confusing too – because as noted, it is a triple-star system.
Alpha Centauri A and Alpha Centauri B are Class G and Class K sun-like stars respectively – and they form the binary star system Alpha Centauri AB.
Alpha Centauri A is about 1.1 times the mass and has 1.5 times the luminosity of our sun, while Alpha Centauri B is slightly smaller, at about 0.9 times the mass of our sun and just half the luminosity.
To the naked eye, these appear as a single star – the third-brightest in the night sky.
It is Alpha Centauri C, also known as Proxima Centauri – a small Class M red dwarf star that isn’t even visible to the naked eye – that is the closest star.
It was discovered in 1915 by Robert Innes, who had been elected as a fellow of the Royal Astronomical Society at age 17.
What excites some is the fact that it has two (possibly three) confirmed planets, Proxima b, an Earth-sized planet in a habitable zone that was discovered in 2016, and last year Proxima d, a sub-Earth planet that orbits very close to the star, was also first observed.
This is in addition to Proxima c, a mini-Neptune that was first discovered in 2019 – although that is still debated by some.
Proxima Centauri is 4.2 light-years from Earth – meaning its light takes 4.2 years to reach us. At the same time, that might seem relatively close given the enormous size of the Milky Way galaxy, with our current technology it would take about 6,300 years to travel there!
The Parker Solar Probe, which NASA developed to study our sun, is also only about the size of modern car – so it likely couldn’t carry the multiple generations of passengers that would be required to make the journey.
However, 6,300 years is actually a notable improvement over Apollo 11, which traveled at 40,000 kilometers an hour – and would have taken 100,000 years to reach Proxima Centauri. In 2016, it was announced that efforts are underway to develop mini-probes that are smaller yet faster and could be sent on the way and could reach our nearest neighbor in a couple of decades.
There is an old saying that getting there is half the fun, but that likely didn’t involve traveling 4.2 light years away.
Bonus Original Photo Essay: Check Out the Space Shuttle Discovery
Author Experience and Expertise: A Senior Editor for 19FortyFive, Peter Suciu is a Michigan-based writer. He has contributed to more than four dozen magazines, newspapers, and websites with over 3,200 published pieces over a twenty-year career in journalism. He regularly writes about military hardware, firearms history, cybersecurity, politics, and international affairs. Peter is also a Contributing Writer for Forbes and Clearance Jobs. You can follow him on Twitter: @PeterSuciu.
January 28, 2023 at 2:14 am
I realize you want to talk about the biological problems of LONG travel, but I think the 6300 year estimate is way wrong, based on the Parker solar probe heading IN towards the sun. A better estimate (because objects leaving the solar system are slowed by the sun’s gravitational pull) is the New Horizons spacecraft, which hits about 46,600 kph at 100 AU, still a LONG way from Proxima Centauri. Given that, the estimate of 100,000 yrs is probably better (from Apollo’s 40 kph). So, in addition to getting our descendants to survive that long, we have to have a spacecraft able to survive 100,000 years. The only things we know how to build that last 100,000 years are rocks…
February 1, 2023 at 6:28 am
I believe there will be massive speed increases with new systems. However, anything but a multi-generational and unmanned mission is currently a pipe dream.
Bringing astronauts will remain elusive for centuries or forever.