Betelgeuse is known for its reddish-orange hue and is typically one of the ten brightest stars visible in the night sky. Its high luminosity makes it an easy target for naked-eye observation from nearly anywhere on Earth. The star’s prominence and distinctive color make it an excellent starting point for stargazers learning the patterns of the celestial sphere.
Finding the Constellation of Orion
The first step in locating Betelgeuse is finding its host constellation, Orion, often called the Hunter. Orion is highly recognizable due to its distinct shape, which resembles a large, tilted hourglass. The constellation is anchored by four bright stars that form a large rectangle.
Look for the three stars clustered in an almost-straight line near the center of this shape. These three stars form Orion’s Belt, which is the most immediate identifying feature of the constellation. Once the Belt is identified, the overall figure of the Hunter is easier to trace. Orion is visible globally, though its orientation changes depending on the observer’s hemisphere.
Pinpointing Betelgeuse Using Pointer Stars
Once Orion’s Belt is identified, it acts as a pointer to Betelgeuse. The star is located at one of the four corners of the large rectangle framing the constellation’s body, specifically marking the Hunter’s right shoulder.
To pinpoint its location, trace an imaginary line diagonally from the three stars of the Belt up toward the two stars forming Orion’s shoulders. When viewed from the Northern Hemisphere, Betelgeuse is the star positioned on the upper-left side of the rectangle, corresponding to the Hunter’s right shoulder.
Confirmation comes from its unmistakable coloration. Betelgeuse shines with a noticeable reddish or orange-red light, which contrasts sharply with the blue-white light of Rigel, located diagonally at the Hunter’s foot. This color difference confirms the location of the red supergiant. Betelgeuse is bright enough to be seen even from light-polluted areas, though its color is clearest under dark skies.
Best Time for Viewing and Stellar Characteristics
Betelgeuse is best observed during the Northern Hemisphere’s winter months, when the Orion constellation is prominent in the evening sky from September through April. Peak viewing occurs in December and January when the constellation is high in the sky after sunset.
Stellar Characteristics
The star’s pronounced red color results from its classification as a red supergiant. This type of star is nearing the end of its life cycle and has expanded to an immense size, causing its outer layers to cool significantly. Betelgeuse possesses a relatively low surface temperature of around 3,600 Kelvin, which shifts the light it emits toward the red end of the spectrum.
Betelgeuse is also known as a semiregular variable star, meaning its brightness changes over time. Its apparent magnitude, or how bright it appears to us, typically varies between 0.0 and +1.6, following a primary cycle lasting roughly 400 days. For example, the “Great Dimming” event of 2019–2020 saw the star’s brightness drop significantly, attributed to a massive ejection of material that formed a temporary obscuring dust cloud.