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If a bright star seems to flicker red, green, or other colors on an autumn night, it may be Capella, Arcturus, or Sirius. For Northern Hemisphere observers in October, look northeast in the evening for Capella, northwest soon after sunset for Arcturus, or southward after midnight and before dawn for Sirius. Which one fits depends on your location and the time you look.
Why a star appears to flash different colors
The apparent color changes come from Earth’s atmosphere, not from the star changing color. As starlight passes through the atmosphere, refraction separates its colors. The effect is easier to notice when a bright star is low in the sky, because its light travels through more atmosphere on the way to you.
EarthSky explains this effect in its October 6, 2026, article, “Flashing star in autumn? Here are 3 candidates”. The three stars below are seasonal possibilities, not a guarantee for every location or observing time.
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| Candidate | When and where to look in October from the Northern Hemisphere | Clue to identify it |
|---|---|---|
| Capella | Northeast at nightfall or early evening | Look for the small nearby triangle of stars called The Kids. |
| Arcturus | Northwest soon after sunset | Follow the curve of the Big Dipper’s handle outward toward it. |
| Sirius | Southward after midnight or before dawn | Extend a line from Orion’s Belt toward it. |
Capella: the evening northeast candidate
EarthSky identifies Capella as its leading candidate for the flashiest star on Northern Hemisphere October evenings. It reports an apparent magnitude of 0.24 and describes Capella as the sixth-brightest star in Earth’s sky, excluding the Sun. The nearby triangle known as The Kids can help confirm the identification.
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Arcturus: the early-evening northwest candidate
From northerly latitudes, Arcturus is a possibility in the northwest soon after sunset. Trace the curve of the Big Dipper’s handle outward to find it. It is descending in the evening sky and, according to EarthSky, sets not long after sunset.
Sirius: the after-midnight or pre-dawn candidate
In October, Northern Hemisphere observers can look southward for Sirius after midnight or before dawn. Orion’s Belt points toward it. Sirius is higher in the sky before dawn for Southern Hemisphere observers, and EarthSky notes that it shines more steadily when higher. In the Northern Hemisphere, it is also higher and steadier in the evening sky during January and February.
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How to get a location-specific view
These directions are broad seasonal cues: without your location and observing time, no candidate can be confirmed or given a precise direction or altitude. EarthSky suggests entering your location into Stellarium to see the sky for your particular place and time.
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