The Science of the Orionid Meteors
The Orionid meteor shower occurs every year between October 2nd and November 7th. This phenomenon happens when Earth passes through the debris stream left behind by Halley’s Comet. Although the meteors can appear anywhere in the sky, they appear to radiate from a point near the constellation Orion, more specifically near the star Betelgeuse and the Orion’s Belt. Under ideal viewing conditions, the shower can produce up to 25 visible meteors per hour. The Orionid meteor shower reaches its peak on October 21st and 22nd.
Meteoroids are pieces of space rock and dust that travel through Earth’s atmosphere. Due to friction with the air and the high speed at which they travel, around 238,000 km/h, they shine brightly for a few seconds, appearing as what we commonly known as meteors or “shooting stars.” Therefore, a meteor shower occurs when a larger-than-normal number of meteors appear to fall from the same point in the sky.
When comets orbit the Sun, the dust they emit gradually spreads out, forming a trail of debris along their orbits. Every year, as Earth passes through these debris trails, the fragments collide with the atmosphere, where they disintegrate and create these glowing streaks across the sky. In the case of Comet Halley, its nucleus releases ice and rocky dust into space.
Skywatching Tips From NASA
The best way to observe the Orionids is in the hours before dawn, in the early hours of the morning, looking directly at the sky from a dark spot away from city lights, with as wide a view of the sky as possible. Binoculars or telescopes are not necessary: the meteor shower is best enjoyed with the naked eye, and your eyes will adapt to the darkness in about 15 to 20 minutes. Since meteor watching can take some time, bring a comfortable chair or blanket and be prepared to spend at least a few minutes looking up. Try to avoid looking at your phone, as bright screens can interfere with your eyes’adjustment to the darkness.
During the meteor shower’s peak days, the weather forecast for Brazil’s Southeast region indicates favorable viewing conditions, with temperatures between 16 and 26 degrees Celsius and no rain forecasted. However, the Moon will be in its waxing phase, producing natural moonlight that may outshine fainter meteors. Therefore, seeking remote locations during the pre-dawn hours can improve viewing conditions.
Halley’s Comet
Halley’s Comet is one of the periodic comets in our Solar System because it has been observed from Earth and mentioned in studies for centuries. It takes about 76 years to complete an orbit around the Sun (passing close to the star and then traveling beyond Neptune).
It was last seen from Earth in 1986 and is not expected to be visible again until 2061, but its debris continues to produce meteor showers every year: the Eta Aquariids in May and the Orionids in October.
The comet was named after Edmond Halley, who discovered in 1705 that three previous comets, seen in 1531,1607 and 1682, seemed to return approximately every 76 years, and suggested that these appearances were, in fact, the same comet. As predicted by Edmond, the comet returned and was named in Halley’s honor. Astronomers have now linked the comet’s appearances to observations dating back more than 2 thousand years.
Until the time of Edmond, comets were believed to make only one pass through the solar system. Halley is often called the most famous comet because it marked the first time astronomers understood comets could be seen more than once in a lifetime.
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The article above was edited by Elisa Nuñez.
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