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Explain xkcd: It's 'cause you're dumb.
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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."


Ambox notice.png This explanation may be incomplete or incorrect: Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.
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) and the closest star in the Northern Celestial Hemisphere. It is a Red dwarf with a mass of 0.144 Solar masses and it is 7–12 billion years old. Because of this low mass the gravitational force 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, 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 the Sun might last about 10 billion years and huge stars only a few hundred million 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. Barnard's star is both very close to the sun (as these things go) and moving 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 within 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.

The title text emphasises 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 and annoyed by its unpleasant behavior.


Ambox notice.png This transcript is incomplete. Please help editing it! Thanks.
[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 dieEEEEEAAA...
[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.

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