2062: Barnard's Star

Explain xkcd: It's 'cause you're dumb.
Revision as of 03:44, 7 May 2023 by Nitpicking (talk | contribs) (Explanation: missing word)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search
Barnard's Star
"Ok, team. We have a little under 10,000 years before closest approach to figure out how to destroy Barnard's Star." "Why, does it pose a threat to the Solar System?" "No. It's just an asshole."
Title text: "Ok, team. We have a little under 10,000 years before closest approach to figure out how to destroy Barnard's Star." "Why, does it pose a threat to the Solar System?" "No. It's just an asshole."


Distances to the nearest stars from 20,000 years ago until 80,000 years in the future

Barnard's Star is a very-low-mass red dwarf about 6 light-years away from Earth in the constellation of Ophiuchus. It is the fourth-nearest known individual star to the Sun after the three components of the Alpha Centauri system; it is the closest star to Earth in the Northern Hemisphere. It is a red dwarf with a mass of 0.144 Solar masses, a diameter one fifth that of the Sun, and it is 7–12 billion years old. Because of this low mass the gravitational pressure in the core is much lower and thus the fusion rate is far smaller than in the core of the Sun. In fact this star is so dim that, even though it's one of the nearest, it can't be seen by the naked eye. The low fusion rate also means that the lifespan of small stars is much longer. While huge stars might last a few hundred million years, and the Sun about 10 billion years, a small red dwarf has a lifespan of about a trillion years.

Barnard's Star is the star with the greatest proper motion in the sky. Proper motion is motion in the sky other than that caused by Earth's rotation or orbit. Barnard's star is both very close to the sun (as these things go) and moving now at a speed of more than 140 km/s toward the Sun. It will make its closest approach to the Sun in approximately 10,000 years, at a distance of about 3.75 light-years.

The image on the right shows different stars near the Sun over 100,000 years and it can be seen that none of them are getting closer than 3 light-years. This is a safe distance to our Solar System and the stars will not influence the orbits of the planets or smaller bodies. It's also obvious that much closer approaches never have happened since the Solar System formed 4.5 billion years ago because otherwise the nearly circular orbits of the planets in the same plane wouldn't be possible. Closer encounters have happened in the past by mostly small stars like Scholz's Star which actually passed through the Oort cloud at a distance of 0.82 light-years about 70,000 years ago, and at least one estimate suggests that a star is expected to pass through the Oort Cloud every 100,000 years or so. This distance is still too far away to influence the orbits of the planets, but those encounters cause comets perturbed from the Oort cloud to enter the inner Solar System roughly 2 million years later.

The comic shows the sizes and the distances not in a proper scale. If the Sun was 1.4 cm (1.4 Mio km in real) in diameter, Barnard's Star would be less than 3 mm at a distance of 356 km. Even Jupiter wouldn't fit into this picture -- at ten times smaller than the Sun, it would be a few pixels, but at a distance of 7.8 m to the Sun and all the other planets would fit into a circle less than 100 meters in diameter. The distances to others stars are far beyond human imagination and at its closest distance a message still takes 3.75 years from Barnard's Star to the Sun.

In regards to "20,000-year-long high-speed flyby", the joke here is suggesting Barnard's Star would need to scream out the maleficent, trolling statement as quickly as possible due to 20,000 years being such a small segment of time relative to the lifespan of the star (and our Sun, for that matter).

The title text emphasizes that this close approach will not be any hazard to the Solar System, but someone is envious of the long lifetime of Barnard's Star or annoyed by its unpleasant behavior (yelling at the sun for 20,000 years would be a minuscule amount of time for the stars, but for humans it would be a vast length of time, and would get annoying very quickly).


[A black sky is shown with a yellow spot near the bottom, left of the center. Three smaller red spots at the diagonal from top left to bottom right indicate a moving star over time. Above these red spots lines are connected to a text that starts and ends with many As, first growing, and at the end getting smaller:]
...AAAAHHi Sun! I was here billions of years before you formed and will shine for trillions of years after you dieEEEEEEAAA...
[Caption below the frame:]
Sometimes, I wonder what Barnard's Star is saying to the Sun as it performs its 20,000-year-long high-speed flyby.

comment.png add a comment! ⋅ comment.png add a topic (use sparingly)! ⋅ Icons-mini-action refresh blue.gif refresh comments!


Uh . . . I'm pretty sure that stars don't talk. (talk) (please sign your comments with ~~~~)

And squirrels don't ring. This comic can be absurd sometimes. 17:05, 22 October 2018 (UTC)
[citation needed] -- 18:05, 22 October 2018 (UTC)
Why are you so sure that stars don't talk? 18:23, 22 October 2018 (UTC)
I think it was a NOVA doco where they describe the inner workings of the sun and how hydrogen atoms, photons, plasma, and magnetic flux interact, and it sounded a heck of a lot like the function of neurons and signals in the brain. Maybe I was just high, but I got to thinking that, with photons from every star in the universe connecting to every other star, the stars are in constant communication with eachother in some sort of neural-like network with each star having it's own neural-like network complete with it's own sentient thoughts (albeit probably far outside the realm of our imagination). FORTY TWO! (talk) (please sign your comments with ~~~~)
Obviously, stars, being in vacuum, don't talk in classic acoustic way. But they emit lot of light, which includes radio emissions ... and remember that properly encrypted signal is hard to recognize from random noise. -- Hkmaly (talk) 23:05, 22 October 2018 (UTC)

Stars can talk but usually don't. Maybe because they are under a lot of pressure ? 08:45, 24 October 2018 (UTC) BadJokeNinja

Am I'm the only one, who is reminded by the beginning "...AAAA" and the ending "EEEEEAAA..." to the "The Man Who Fell Sideways" comic?-- 12:17, 24 October 2018 (UTC)

"a small Red dwarf has a lifespan of about a trillion years." A trillion years? Any source for this? The universe is around 14 billion years old. 13:32, 24 October 2018 (UTC)comicreader

That doesn't mean it's that old now. It means it will last that long, which means it's a relative youngster at this stage of its life. I'm sure a trillion years is a very general estimate for its lifespan, which is highly dependent on its mass. As for the source of this estimate, it's probably well-sourced on Wikipedia that serves as the source of much of the explanation's current content. Ianrbibtitlht (talk) 13:48, 24 October 2018 (UTC)
And click the Wiki link for Red dwarf in the explanation. You will read: "...Red dwarfs therefore develop very slowly, maintaining a constant luminosity and spectral type for trillions of years, until their fuel is depleted. Because of the comparatively short age of the universe, no red dwarfs exist at advanced stages of evolution." --Dgbrt (talk) 18:34, 24 October 2018 (UTC)

Faster comunication than photons could be possible with plasma entanglement but I'm still skeptical as to whether or not stars are big giant sentient brains. Why is it traveling so fast I wonder... a remnant of some previous galactic merger?

Two points. First, a star called Gliese 710 will pass through the Solar System in about 1.3 million years. Predictions of how close it will come vary, but seem to cluster around 0.3 lighyears (ly) and 0.05 ly. Both estimates mean the star will pass through the Oort cloud. There is even a small chance it will pass just outside the Kuiper belt. This star is informally called "Uncle Jimbo's Star" because it's coming right at us. Second, your basic star-shaped star is an easy thing to study in detail and an easy thing to model. The sun has a radiative core; it cannot add fresh fuel. As a result, it burns up about 10% of its hydrogen and goes out. Barnard's star is convective throughout, so it constantly mixes fresh hydrogen into its core. As a result, Barnard's star will consume 50 - 80 % of its hydrogen before going out. The reacting masses of the Sun and Barnard's star are almost the same. Since the bolometric luminosity of Barnard's star is around 0.0035 that of the sun, it can reasonably be expected to last around 300 times longer - around 3 trillion years. That's a crude guess. More accurate models give an even longer life. Some of the really little ones will still be shining some 10 trillion years from now. -- Adeblanc (talk) 14:44, 2 February 2023 (please sign your comments with ~~~~)