# How old is the starlight you see tonight? > How old is the starlight you see tonight? From a few years to thousands of years, star by star, and why almost every star you see is still shining. HTML: https://www.theuniversecounts.com/stars/the-stars-you-can-see/old-starlight Numbers as of 2026-11-04 13:00 UTC. Live ones keep changing on the HTML page. The starlight in your eyes tonight set out years, thousands of years, or centuries ago. A star's distance in light-years is also the age of its light. Sirius's light left it 8.6 years ago. Rigil Kentaurus, the nearest star you can see with your eyes alone, is in the southern sky; its light is 4.34 years old. Deneb's light left between 1,240 and 2,830 years ago, because nobody knows its distance well. As far as astronomers know in 2026, almost every star you see is still shining. - Time sunlight takes to reach Earth, at today's Earth–Sun distance: 8m 14s - Time light takes to travel from the Moon to Earth, at today's distance: 1.24 s - Time for light from Earth to reach Voyager 1: 23h 58m 07s ## Light takes time How long does starlight take to reach Earth? Light is the fastest thing there is. It covers 299,792.458 kilometres every second. Even so, crossing something as huge as the universe takes it time. Right now, sunlight takes 8m 19s to reach you, so you actually see the Sun as it was a few minutes ago. The stars are much farther away, so astronomers measure their distances in light-years. A light-year is not a time but a distance: how far light travels in one year, 9.5 trillion kilometres. An airliner flying non-stop at cruising speed would take about 1.2 million years to cover it. That makes every star distance a clock as well. A star ten light-years away is seen by light that left it ten years ago. So when you look up, you never see the stars as they are now. You see each one as it was when its light set out, and every star shows you a different moment. The night sky is not one picture of the present. It is many pictures of the past, taken at different times and arriving together. ## From a few years to many centuries How old is the light from the stars? The light from the bright stars is anything from a few years to thousands of years old. Procyon, the little dog's star near Orion, sends light 11.5 years old. Vega's light is 25.0 years old. Go further out and the light gets older fast. Spica's light left it 250 years ago. Long before anyone who is alive today was even born. Antares, the red heart of the Scorpion, shines with light about 550 years old. Rigel, at Orion's foot, shines with light about 860 years old. The farther the star, the less sure the number. Close stars are measured precisely, by how they seem to shift as Earth goes round the Sun. Far stars shift too little, so astronomers lean on other methods, and these don't always agree. For Deneb, the brightest star of the Swan, the light is between 1,240 and 2,830 years old. That spread is not carelessness. It is how much is still unknown about one of the most luminous stars you can see. Comparisons are computed live on the HTML page. ## Light from the year you were born Which star's light left when you were born? Somewhere in the sky is a star whose light set out the year you were born, and it changes as you get older. A person in their twenties may look at Fomalhaut, whose light is 25.1 years old. In their thirties, it could be Pollux, at 33.8 years. A baby born in 2024 could expect to live about 73 years, on the world average. Some stars you can see have light older than that. Regulus, in the Lion, sends light 79 years old. From the southern sky, Gacrux, at the top of the Southern Cross, sends light 88.6 years old. Look at them and you see light that set out more than a lifetime ago. Seen that way, a clear night holds a lifetime of moments. Each star you can name is a different year of the past, all arriving at once. ## Are the stars you see already dead? Are the stars we see dead? It is a common idea that many of the stars you see are long dead. But for almost all of them this is not true. The light of a bright star left it years or centuries ago, but stars live for millions to trillions of years. Even the shortest-lived bright stars almost certainly still shine. The best-known exception might be Betelgeuse, the red giant at Orion's shoulder. It will one day explode as a supernova. NASA expects it to happen about 100,000 years from now. Some astronomers argue it could come within a few centuries, and others dispute their reasoning; the range runs between 300 and 100,000 years. Its light is between 440 and 880 years old. So on the shortest estimate, Betelgeuse may already have exploded, with the news still on its way, carried by light as the messenger. On the longest, it will shine for ages yet. Nobody knows which. Even a dead star can keep shining. When a star like the Sun runs out of fuel, it leaves a white dwarf, a core about the size of Earth that cools slowly over billions of years. ## Light older than our species The oldest light you can see Deneb's light set out within recorded history, which goes back about 5,200 years. To see light older than any city, look beyond our galaxy. From the northern hemisphere, on a dark autumn night, you can find a faint smudge near Cassiopeia. It is the Andromeda Galaxy, a whole galaxy of stars too far away to see one by one, and its light set out 2.5 million years ago. NASA puts it this way: the light you see left when our earliest ancestors figured out stone tools. Our own species, Homo sapiens, is about 320,000 years old. So when you look at Andromeda, you see light that was already most of the way here before there were any people like us to see it. ## Looking back together A sky full of the past Since you opened this page, the light now on its way from Vega has come [counts up live on the page] kilometres closer. Most of the time we look at the sky as if it were a picture of now. It is closer to a letter from the past, written at many different times and delivered all at once, to everyone who looks up. The person next to you sees the exact same old light, right now. Sometimes the letter brings news. In 1054, astronomers in China saw a new star blaze up, bright enough to see by day for nearly a month. It was a star exploding, thousands of years earlier, and its remains are the Crab Nebula. The light of that ending reached them on its own long schedule, as all starlight does. ## FAQ ### Are we seeing the past when we look at stars? Yes. Light takes time to cross space, so you see every star as it was when its light left it. Sirius's light left it 8.6 years ago; Deneb's left between 1,240 and 2,830 years ago. The farther the star, the further back in time you see it. ### Do dead stars still shine? Their remains can. A star like the Sun ends as a white dwarf, a hot core about the size of Earth that cools slowly over billions of years. But almost all the stars you see in the night sky are still alive: their light is young compared with their lives. ### Have we ever seen a star die? Yes. In 1054, astronomers in China recorded a "guest star" bright enough to see by day for nearly a month. It was a supernova, and its remains are the Crab Nebula. ### How many of the stars we see are already dead? Almost certainly none of the ones you can name, with one possible exception. Betelgeuse will explode one day, perhaps within a few centuries or perhaps not for 100,000 years, and its light takes between 440 and 880 years to reach us. Astronomers can't yet say whether it has already gone. ### Which star's light left the year I was born? Find a star whose distance in light-years matches your age. Fomalhaut's light is 25.1 years old, Pollux's 33.8 and Regulus's 79. ## Related - [The night sky tonight](https://www.theuniversecounts.com/you/your-sky/star-map.md) - [Counting the stars you can see](https://www.theuniversecounts.com/stars/the-stars-you-can-see/how-many-stars-can-you-see.md) - [How long does sunlight take to reach Earth?](https://www.theuniversecounts.com/solar-system/the-sun/sunlight-to-earth.md) Which star's light set out the year you were born? ## Sources - Age of our species, Homo sapiens, from the oldest known fossils (Estimated): [Nature: The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age (Richter et al. 2017, Nature 546, 293)](https://www.nature.com/articles/nature22335) - Diameter of a grain of sand (Estimated): [USGS: USGS Open-File Report 2006-1195: Nomenclature](https://pubs.usgs.gov/of/2006/1195/htmldocs/nomenclature.htm) - Distance from the Sun to the outer edge of the Oort cloud (Debated): [NASA: Oort Cloud: Facts](https://science.nasa.gov/solar-system/oort-cloud/facts/) - Distance to Antares (Estimated): [The Astronomical Journal (arXiv version): An Updated 2017 Astrometric Solution for Betelgeuse (Harper et al. 2017, AJ 154, 11; doi:10.3847/1538-3881/aa6ff9)](https://arxiv.org/pdf/1706.06020); [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to Betelgeuse (Debated): [The Astrophysical Journal (arXiv version): Standing on the shoulders of giants: New mass and distance estimates for Betelgeuse through combined evolutionary, asteroseismic, and hydrodynamical simulations with MESA (Joyce et al. 2020, ApJ 902, 63; doi:10.3847/1538-4357/abb8db)](https://arxiv.org/abs/2006.09837); [The Astronomical Journal (arXiv version): An Updated 2017 Astrometric Solution for Betelgeuse (Harper et al. 2017, AJ 154, 11; doi:10.3847/1538-3881/aa6ff9)](https://arxiv.org/abs/1706.06020); [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to Deneb (Debated): [Astronomy & Astrophysics (arXiv version): Quantitative spectroscopy of Deneb (Schiller & Przybilla 2008, A&A 479, 849; doi:10.1051/0004-6361:20078590)](https://arxiv.org/pdf/0712.0040); [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to Fomalhaut (Measured, with error): [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to Gacrux (Measured, with error): [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to Pollux (Measured, with error): [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to Procyon (Measured, with error): [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to Proxima Centauri (Measured, with error): [Astronomy & Astrophysics: Gaia Data Release 3: Summary of the content and survey properties (Gaia Collaboration, Vallenari et al. 2023)](https://doi.org/10.1051/0004-6361/202243940); [ESA: Gaia Data License](https://www.cosmos.esa.int/web/gaia-users/license) - Distance to Regulus (Measured, with error): [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to Rigel (Estimated): [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to Sirius (Measured, with error): [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to Spica (Measured, with error): [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Distance to the Andromeda galaxy (Measured, with error): [The Astrophysical Journal (via arXiv): A Sub-2% Distance to M31 from Photometrically Homogeneous Near-Infrared Cepheid Period-Luminosity Relations Measured with the Hubble Space Telescope (Li et al. 2021, ApJ 920, 84)](https://arxiv.org/abs/2107.08029); [NASA: Messier 31 (The Andromeda Galaxy)](https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-31/) - Distance to Vega (Measured, with error): [Astronomy & Astrophysics: Validation of the new Hipparcos reduction (van Leeuwen 2007, A&A 474, 653)](https://arxiv.org/abs/0708.1752) - Earth's diameter at the equator (Measured): [NASA NSSDCA: Earth Fact Sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html) - Expected time until Betelgeuse explodes as a supernova (Debated): [NASA Science: What is Betelgeuse? Inside the Strange, Volatile Star](https://science.nasa.gov/universe/what-is-betelgeuse-inside-the-strange-volatile-star/); [Monthly Notices of the Royal Astronomical Society: Saio, Nandal, Meynet & Ekström 2023, The evolutionary stage of Betelgeuse inferred from its pulsation periods](https://arxiv.org/abs/2306.00287); [Research Notes of the AAS: Molnár, Joyce & Leung 2023, Comment on the Feasibility of Carbon Burning in Betelgeuse](https://doi.org/10.3847/2515-5172/acdb7a) - Jupiter's diameter at the equator (Measured): [NASA NSSDCA: Jupiter Fact Sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html) - Length of a light-year (Measured): [NASA JPL Solar System Dynamics: Astrodynamic Parameters](https://ssd.jpl.nasa.gov/astro_par.html) - Length of recorded history, since the first writing (Estimated): [British Museum: How to write cuneiform](https://www.britishmuseum.org/blog/how-write-cuneiform) - Speed of light in a vacuum (Measured): [BIPM: SI defining constants](https://www.bipm.org/en/measurement-units/si-defining-constants) - The International Space Station's orbital speed (Measured): [NASA: Station Facts](https://www.nasa.gov/international-space-station/space-station-facts-and-figures/) - The Moon's mean diameter (Measured): [NASA NSSDCA: Moon Fact Sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html) - The Sun's mean diameter (Measured, with error): [NASA NSSDCA: Sun Fact Sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html); [International Astronomical Union / The Astronomical Journal: Prša et al. 2016, IAU 2015 Resolution B3 on Recommended Nominal Conversion Constants for Selected Solar and Planetary Properties](https://arxiv.org/abs/1510.07674) - Time for light from Earth to reach Voyager 1 (Measured): [NASA JPL: Horizons API documentation](https://ssd-api.jpl.nasa.gov/doc/horizons.html) - Time light takes to travel from the Moon to Earth, at today's distance (Measured): [NASA JPL: JPL Horizons observer ephemeris of the Moon from Earth (illumination, range and one-way light time)](https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND='301'&OBJ_DATA='NO'&CENTER='500@399'&EPHEM_TYPE='OBSERVER'&QUANTITIES='10,20,21'&START_TIME='2026-10-29%2019:00'&STOP_TIME='2026-10-29%2020:00'&STEP_SIZE='1h') - Time sunlight takes to reach Earth, at the mean Earth–Sun distance (1 au) (Measured): [International Astronomical Union (hosted by SYRTE, Observatoire de Paris): IAU 2012 Resolution B2 on the re-definition of the astronomical unit of length](https://syrte.obspm.fr/IAU_resolutions/Res_IAU2012_B2.pdf); [BIPM: SI defining constants](https://www.bipm.org/en/measurement-units/si-defining-constants); [NASA NSSDCA: Earth Fact Sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html) - Time sunlight takes to reach Earth, at today's Earth–Sun distance (Measured): [NASA JPL: JPL Horizons observer ephemeris of the Sun from Earth (range and one-way light time)](https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND='10'&CENTER='500@399'&EPHEM_TYPE='OBSERVER'&QUANTITIES='20,21'&START_TIME='2026-10-28%2020:00'&STOP_TIME='2026-10-28%2021:00'&STEP_SIZE='1h') - Typical cruising speed of a long-haul airliner (Estimated): [EUROCONTROL: Aircraft Performance Database: B789 (Boeing 787-9)](https://contentzone.eurocontrol.int/aircraftperformance/details.aspx?ICAO=B789); [EUROCONTROL: Aircraft Performance Database: A388 (Airbus A380-800)](https://contentzone.eurocontrol.int/aircraftperformance/details.aspx?ICAO=A388) - Typical muzzle velocity of a rifle bullet (Estimated): [Headquarters, Department of the Army: FM 3-22.9 Rifle Marksmanship: M16A1, M16A2/3, M16A4, and M4 Carbine (April 2003)](https://www.bits.de/NRANEU/others/amd-us-archive/FM3-22.9%2803%29.pdf) - World average life expectancy at birth in 2024 (Measured, with error): [United Nations, Department of Economic and Social Affairs, Population Division: World Population Prospects 2024: Summary of Results](https://population.un.org/wpp/assets/Files/WPP2024%5FSummary-of-Results.pdf)