Orionid meteor shower peaks, promising a spectacle until Thursday; phenomenon caused by debris from Halley’s Comet

The Orionid meteor shower reached its peak in the early hours of October 21, 2025, with maximum visibility between 3 a.m. and 5 a.m., and remains visible until the night of October 23. The phenomenon, caused by debris from Halley’s Comet, occurs annually with its radiant in the Orion constellation. In ideal conditions, up to 20 meteors per hour can be observed in areas with low light pollution. Astronomers recommend locations far from urban centers to enjoy the spectacle.

The event attracts amateur astronomers and curious observers seeking clear skies to witness the luminous trails. The peak varies between October 21 and 23 due to the irregular distribution of debris.

• Ideal time: Between 3 a.m. and 5 a.m., when the radiant is highest.
• Location: Look east, toward the Orion constellation.
• Conditions: Clear skies and minimal artificial lighting.

Origin of the phenomenon

The Orionids occur when Earth passes through debris left by Halley’s Comet. These fragments burn up upon entering the atmosphere, creating bright trails. The phenomenon is visible in both hemispheres, with optimal conditions in the late night.

The Orion constellation, the apparent origin of the meteors, aids in locating the radiant. Meteor rates depend on factors like the radiant’s position and cloud cover.

Factors affecting visibility

Light pollution is the main obstacle in urban areas, reducing visibility to 5–10 meteors per hour. In rural areas, rates can reach 20 meteors.

Weather conditions, such as cloudy skies, also impact observation.

The radiant, positioned about 50° above the eastern horizon after 3 a.m., enhances visibility.

In cities like São Paulo, forecasts suggest up to 11 meteors per hour at the peak, with better results in remote areas.

Observation tips

No telescopes or binoculars are needed to enjoy the spectacle. A dark location, away from artificial lights, is sufficient.

Eyes take about 20 minutes to adjust to darkness, improving meteor perception.

Apps like Stellarium help locate the Orion constellation accurately.

Patience is key, as brighter meteors appear sporadically.

Variation in peak timing

The peak, spanning October 21 to 23, varies due to the scattered debris from Halley’s Comet. Gravitational interactions and Earth’s orbit influence activity.

Solar longitude calculations pinpointed the peak at 9 a.m. Brasília time on October 21. Subsequent nights still offer good viewing opportunities.

How to enjoy the spectacle

No special equipment is required, but choosing the right location is crucial. Rural areas or parks far from cities provide optimal conditions.

• Bring chairs or blankets for comfort.
• Avoid using phones or flashlights to maintain visual adaptation.
• Use astronomy apps to locate the radiant.

Best time to observe

Visibility is best in the late night, when the radiant reaches 50° above the eastern horizon. In clear skies, the brightest meteors appear between 45° and 90° from the radiant.