In the early hours of 22 October, anyone awake before dawn and far from city lights can see quick streaks of light across the spring sky. These are the Orionids. Each streak is a grain of dust left behind by Halley’s Comet, entering the atmosphere at tens of kilometres per second and burning up in less than a second.
For the month’s other events, see October 2026 Sky.
What the Orionids are
A meteor shower happens when the Earth passes through a stream of dust left by a comet. The grains, usually smaller than a grain of sand, hit the atmosphere at high speed, heat the air around them and produce a trail of light: the “shooting star”.
Because the grains of a single shower travel on parallel paths, the trails seem to come from one point in the sky, the radiant. For the Orionids, that point lies in the constellation of Orion, just north of the reddish star Betelgeuse, according to NASA. Hence the name.
According to the International Meteor Organization (IMO) 2026 calendar, the Orionids are active from 2 October to 7 November, with the maximum on 21 October. The radiant lies at right ascension 95° and declination +16°.
The dust of Halley’s Comet
The “parent” of the Orionids is Comet 1P/Halley, as NASA and the American Meteor Society (AMS) point out. Halley returns to the inner Solar System roughly every 76 years. Its last passage was in 1986; the next will be in 2061.
On each return, the Sun’s heat makes the comet shed ice and dust, which spreads out along its orbit. The Earth crosses this trail twice a year: in May, with the Eta Aquariids, which are well placed for observers in the southern hemisphere, and in October, with the Orionids.
How many meteors to expect
The IMO gives the Orionids a zenithal hourly rate (ZHR) of about 20. The AMS and NASA speak of about 10 to 20 meteors per hour under dark skies. The ZHR is an idealised figure: a perfect sky, no light pollution and the radiant directly overhead. From a city, or with the Moon in the sky, you will see far fewer.
Some years bring surprises. The IMO records that from 2006 to 2009 the Orionids reached 40 to 70 per hour. Nothing similar is forecast for 2026.
The meteors enter at about 66 km/s, according to the IMO, the AMS and NASA. NASA notes that fast meteors like these sometimes leave glowing trains lasting a few seconds and can become fireballs, very bright meteors.
How and when to see them from Brazil
I calculated the times below with the Skyfield library and JPL’s DE421 ephemeris, for the night of the peak, 21–22 October 2026, in Brasília time (BRT, UTC−3).
In São Paulo, the radiant rises at 22:52 BRT on 21 October (01:52 UTC on the 22nd). At 01:00 on the 22nd it is about 26° up, at 03:00 about 45°, and it culminates at about 50° at 04:25. Astronomical twilight begins at 04:09; the Sun rises at 05:27.
In Brasília, the radiant rises at 22:47. At 01:00 it is about 29° up, at 03:00 about 51°, and it culminates at about 58° at 04:30. Twilight begins at 04:26; the Sun rises at 05:39.
The Moon gets in the way a little. It will be waxing gibbous, with about 81% of its disc lit; Full Moon only arrives on 26 October, at 01:12 BRT (04:12 UTC). It sets at 02:56 in São Paulo and 02:57 in Brasília. The AMS warns that in 2026 the dark sky at the peak lasts only a few hours between moonset and dawn.
The best window falls between moonset and twilight: from 02:56 to 04:09 in São Paulo and from 02:57 to 04:26 in Brasília. At that hour the radiant is already high and the sky is dark. The nights of 20–21 and 22–23 October are also worth trying, with the Moon setting earlier on the first and later on the second.
Find a spot away from street lighting, lie back on a reclining chair or a blanket, and let your eyes adjust to the dark for about 20 minutes without looking at your phone screen. The naked eye is all you need: telescopes and binoculars narrow the field too much. NASA recommends looking about 45 to 90 degrees away from the radiant, where the trails are longer. From Brazil, Orion rises in the east and is already high before dawn, with Orion’s Belt (known in Brazil as the Três Marias, “Three Marys”) easy to find.
Meteors in ancient cultures
In China, chroniclers recorded the phenomena of the sky. The Spring and Autumn Annals (Chunqiu), the chronicle of the state of Lu, record for 687 BC a night on which “the fixed stars were not visible” and, at midnight, “stars fell like rain”. The record is usually linked to the Lyrids, an April shower, but in 2004 Sang-Hyeon Ahn proposed that it was the Eta Aquariids, the sister shower of the Orionids. For the Orionids, Kinsman and Asher cite as the oldest a Chinese record from AD 288, which Ahn attributes to the Leonids.
In Greece, Aristotle discussed shooting stars in Book I, chapter 4, of the Meteorology (4th century BC). For him, earth warmed by the Sun gave off a dry, hot exhalation that rose to the region just below the Moon. When the motion of the heavens stirred this matter, it caught fire: “shooting stars”, “torches” and other passing fires, always close to the Earth, below the Moon. The word “meteor” comes from the Greek meteōros, “lofty”, “that which is on high”.
Some peoples revered stones that had fallen from the sky. Herodian, in Book V, chapter 3, of his History of the Empire, describes the temple of the sun god Elagabal at Emesa, in Syria. There was no statue made by human hands, but a large, cone-shaped black stone that worshippers said had fallen from Zeus. The young priest of this cult became emperor of Rome in AD 218 and became known by the god’s name. Today the stone is assumed to have been a meteorite, a modern hypothesis that cannot be confirmed, because the stone has not survived.
Questions answered
Do I need to look at Orion to see the Orionids?
The meteors appear all over the sky; Orion only shows where they seem to come from. NASA suggests looking about 45 to 90 degrees away from the radiant.
Do the meteors reach the ground?
Orionid grains are far too small and burn up completely in the atmosphere, tens of kilometres up.
Which is the best night?
The night of 21–22 October, between moonset and the start of twilight: from 02:56 to 04:09 in São Paulo and from 02:57 to 04:26 in Brasília (BRT).
Will Halley’s Comet appear?
The comet does not return to the Sun’s vicinity until 2061. What we see now is the dust it left on earlier passages.
Mini-glossary
- Meteor: the trail of light produced when a grain from space burns up in the atmosphere.
- Radiant: the point in the sky from which the meteors of a shower seem to come.
- ZHR: zenithal hourly rate, the number of meteors per hour an observer would see under ideal conditions.
- Fireball: a very bright meteor, sometimes brighter than the planets.
- Astronomical twilight: the moment the sky starts to brighten before sunrise, with the Sun 18° below the horizon.
Bibliography
AHN, Sang-Hyeon. A catalogue of meteor showers and storms in Korean, Japanese, Chinese histories. Journal of Astronomy and Space Sciences, v. 21, n. 4, p. 529–552, 2004.
AMERICAN METEOR SOCIETY. Meteor Shower Calendar 2026–2027. Available at: https://amsmeteors.org/meteor-showers/meteor-shower-calendar/.
ARISTOTLE. Meteorologica. Translated by H. D. P. Lee. Cambridge, MA: Harvard University Press, 1952. (Loeb Classical Library, 397).
HERODIAN. History of the Empire. v. 2 (books 5–8). Translated by C. R. Whittaker. Cambridge, MA: Harvard University Press, 1970. (Loeb Classical Library, 455).
INTERNATIONAL METEOR ORGANIZATION. 2026 Meteor Shower Calendar. Available at: https://www.imo.net/files/meteor-shower/cal2026.pdf.
KINSMAN, J. H.; ASHER, D. J. Orbital dynamics of highly probable but rare Orionid outbursts possibly observed by the ancient Maya. Monthly Notices of the Royal Astronomical Society, v. 493, n. 1, p. 551–558, 2020.
NASA. Orionids. NASA Science. Available at: https://science.nasa.gov/solar-system/meteors-meteorites/orionids/.