Southern delta-Aquariids from Rio de Janeiro in 2026

Southern delta-Aquariids from Rio de Janeiro: the short answer

Marginal from Rio de Janeiro. Maximum 10:23 on 31 July 2026; the radiant reaches 83.1° at 02:01 and the rate for this city's measured sky tops out at 0.3 an hour with the Moon 98% lit.

That ranks it 9th of twelve from Rio de Janeiro this year, behind the Geminids (7.8/h) and the Perseids (2.1/h).

The radiant track over this city

Aquarius carries the radiant. From Rio de Janeiro it clears the horizon at 19:33 on a bearing of 108° (ESE), reaches 83.1° at 02:01 in the north, and drops back below the horizon at 08:29. Within the observing window it peaks at 83.1°.

When it gets dark here

Rio de Janeiro loses the Sun at 17:30 and gets it back at 06:27. True astronomical darkness — the only part that counts for faint meteors — runs 18:48 to 05:09, 10 h 21 min out of 12 h 57 min of night.

Local solar midnight, the true middle of the night, falls at 23:59 here rather than at 00:00: America/Sao_Paulo runs 7 minutes behind mean solar time at 43.18°W. That offset is why the best hour on this page is not the hour you would guess from the clock.

What the Moon does here

Moonlight is the limiting factor on this night from Rio de Janeiro. The Moon is 98% lit and only 1 of 13 sampled hours are moon-free. Moonrise 18:33. Moonset 07:41. At the best hour it stands 35.4° above the horizon, 12° from the radiant, pulling the limiting magnitude down to 2.87.

Why 0 an hour and not 25

Converting ZHR 25 into something useful for Rio de Janeiro means multiplying by sin(83.1°) and dividing by 3.2 raised to (6.5 − 2.87). That lands at 0.3 meteors an hour, from fast 40.6 km/s entries.

Hour by hour the modelled rate runs from 0.0 at 18:00 (radiant -19.9°) to 0.0 at 06:00 (radiant 33.7°), peaking at 0.3. That spread across 13 hours is why a "what time" answer beats a "how many" answer.

The stream comes from Comet 96P/Machholz and is listed as active 12 July to 23 August, so 31 July 2026 is the best night from Rio de Janeiro rather than the only one.

Watching from around Rio de Janeiro

Rio de Janeiro is the 44th largest of the 300 cities covered here, with a population of 6.75 million at 12 m above sea level. The nearest other cities on the site are Belo Horizonte (341 km NNW), São Paulo (360 km WSW), Curitiba (678 km WSW) — close enough that the radiant altitudes barely change, far enough that sunset and moonrise do.

What this page does not know

Rates on this page are computed against this city's own measured sky brightness, derived from satellite night-lights data. That is a calculated brightness for the point directly overhead, not a survey of your street: a park on the edge of town and a lit car park in the centre share the same figure here and will not look the same. It is also zenith-only, while the Bortle scale describes the whole sky from horizon to horizon.

Cloud cover is a forecast, not a constant, so it is resolved when you load the tonight card and is deliberately absent from this prerendered page — the hourly table shows "unavailable" rather than assuming clear skies. Meteor outbursts, local terrain and building horizons are not modelled.

A single observer with an unobstructed horizon typically records 30–50% below the ideal-sky figure. Give your eyes twenty minutes to adapt, keep bright screens away, look about halfway up the sky rather than straight at the radiant, and count for a full hour before judging a shower.