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Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Proxima Centauri is the closest star to the Sun after the Sun itself, at roughly 4.24 light-years away. It is also too faint to see without a telescope, a small and violently active red dwarf, and the host of at least one planet that sits in its star’s habitable zone. That last point is where most popular coverage goes wrong: a planet being in the habitable zone is a statement about orbital energy, not evidence that the planet has water, an atmosphere, or life. The facts below separate what is measured from what is only possible.
How far away is Proxima Centauri?
NASA’s Sun facts page gives the distance as 4.24 light-years. NASA’s Proxima Centauri overview describes it more loosely as just over four light-years from Earth, which is the same measurement rounded. One light-year is about 6 trillion miles, or 9.5 trillion kilometers, so the star lies roughly 25 trillion miles away. Light leaving it today reaches Earth about four years later, which is why any event there is only observed in the past.
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Can you see Proxima Centauri without a telescope?
No. NASA states that Proxima Centauri is not visible to the naked eye because its average luminosity is very low. Even though it is the nearest star to us, its brightness falls far below what human eyes can detect under ordinary dark-sky conditions. Observers who want to see it need a telescope, and the Alpha Centauri stars next to it are the brighter members of the same neighborhood.
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What kind of star is it?
Proxima is a red dwarf with about one-eighth the mass of the Sun, according to NASA’s Proxima Centauri overview, which was originally released November 1, 2013 and updated August 17, 2025. Its small mass means it burns fuel slowly, and NASA predicts the star will remain on the main sequence for another four trillion years. That figure is a model-based prediction, not a measured countdown, and NASA describes it as about 300 times the current age of the universe.
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It is an active flare star
Proxima’s brightness does not stay steady. NASA explains that its internal convection processes contribute to random, dramatic changes in brightness, which makes the star a flare star. Flares are sudden bursts of energy from the stellar surface, and they are the most important complication for anyone thinking about planets around this star. Activity like this is observed; what it means for planetary atmospheres is an inference, discussed below.
The Alpha Centauri neighborhood
Proxima is part of the Alpha Centauri triple system. Its two companions, Alpha Centauri A and B, form a closer pair, and NASA’s overview says Proxima takes more than half a million years to orbit that pair. So it is best described as the nearest star and the most distant member of the group, not as one of three equal stars sitting side by side. That distinction matters when people picture the sky from a planet around Proxima, where the other two stars would appear as a bright pair rather than as a tight trio.
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- Proxima Centauri b is an exoplanet orbiting in the habitable zone of the star Proxima Centauri, which is the closest star to the Sun, making it the closest known exoplanet to the Solar System.
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Does Proxima Centauri have planets?
Yes, but the count and confirmation status depend on which source and date you use. NASA’s broader overview says at least one planet and possibly two more orbit Proxima. The planets are listed below with the values NASA reports for each.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware match| Feature | Proxima b | Proxima d |
|---|---|---|
| Announced | 2016 | 2025 (per NASA’s catalog listing) |
| Type described by NASA | Roughly Earth-sized, in the habitable zone | Terrestrial |
| Mass | 1.27 Earth masses (NASA Proxima b model page) | 0.26 Earth masses (NASA catalog estimate) |
| Radius | Not stated in the cited NASA material | 0.692 Earth radii (NASA catalog estimate) |
| Orbital period | 11.2 days (NASA Proxima b model page) | 5.1 days (NASA catalog estimate) |
| Orbital radius | Not stated in the cited NASA material | 0.02881 AU (NASA catalog estimate) |
| Atmosphere | Not known | Not stated in the cited NASA material |
These values are parameters reported by NASA, not proof that either world resembles Earth in composition or climate. Proxima d’s listing is a recent announcement, so it should be treated as a catalog entry that may be refined rather than as a settled characterization.
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- Proxima Centauri b is an exoplanet orbiting in the habitable zone of the star Proxima Centauri, which is the closest star to the Sun, making it the closest known exoplanet to the Solar System.
- Astronomy and science fans will love this design.
- Hardcover journal with 240 line-ruled pages (120 sheets)
- Built-in elastic closure and ribbon bookmark
- Includes an expandable inner storage pocket and a pen holder
Proxima b and the habitable zone
A habitable zone is the range of distances around a star where liquid water could potentially exist on the surface of an orbiting planet. Proxima b sits in that range, which is why it attracts so much attention. But the label describes temperature conditions that could allow water, not whether water is present. NASA says Proxima b’s atmosphere is not known, and its overview states directly: “Whether the planet first discovered around this nearest star, nicknamed Proxima b, might be potentially habitable is so far unknown.”
Why flares make the habitability question harder
NASA’s 2021 account of a study describes observations taken over 40 hours in 2019. The campaign captured an extremely high-energy flare along with many other large, medium, and small flares. Meredith MacGregor, an astronomer at the University of Colorado and the lead author of that study, said: “It’s hard to imagine that life could emerge, being subjected to radiation that frequently.” That is one scientist’s assessment of the environment, not a consensus conclusion about Proxima b. The observed flares are real measurements; whether they strip or prevent an atmosphere over time is a question still under investigation.
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What to check before repeating a Proxima fact
- Distance: NASA gives 4.24 light-years on its Sun facts page and “just over four light-years” in its Proxima overview.
- Visibility: it is not visible to the naked eye.
- Planet count: cite NASA’s catalog and its date. Proxima d was announced in 2025, so older articles may omit it.
- Habitability: say “in the habitable zone,” never “habitable” or “inhabited,” unless a future study establishes those conditions.
The simplest accurate summary is that Proxima Centauri is a nearby, faint, flaring red dwarf with at least one planet in its habitable zone, and the planets’ surface conditions and atmospheres remain unknown.
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