Betelgeuse is a massive red supergiant star easily visible to the naked eye. It is notable for its distinct color and sheer size—estimated to be about 700 times the diameter of the Sun. It is also a semi-regular variable star whose brightness changes over time. This star is one of the brightest stellar objects we can observe, often ranking as the tenth brightest star in the sky. Understanding where to look for this star begins with locating the larger celestial pattern it calls home.
Identifying Betelgeuse’s Home Constellation
The search for Betelgeuse starts with finding the constellation Orion, a prominent and easily identifiable pattern called “The Hunter.” This equatorial constellation is visible from nearly all inhabited regions of the Earth. Orion’s most distinguishing feature is a straight line of three bright stars that form the Hunter’s Belt. Locating this Belt is the first step, as the rest of the constellation’s trapezoid shape branches out from this feature, providing a clear map to pinpoint Betelgeuse.
Pinpointing Betelgeuse within the Constellation
Betelgeuse is situated in the upper portion of Orion, marking what is typically interpreted as the Hunter’s right shoulder. When viewed from the Northern Hemisphere, this position corresponds to the bright star located up and to the left of the three stars that form Orion’s Belt. Its location makes it one of the four bright stars that define the main body of the Hunter figure.
A helpful technique for pinpointing Betelgeuse is to use the three Belt stars as a guidepost. Look diagonally upward from the Belt toward the star that appears distinctly reddish. This differentiates Betelgeuse from its brilliant counterpart, Rigel, which is a blue-white star marking the Hunter’s opposite foot. Betelgeuse is the second brightest star in the constellation.
Seasonal Visibility and Optimal Viewing
Orion is most prominently visible in the night sky during the late autumn, winter, and early spring months. For observers in the Northern Hemisphere, Betelgeuse begins to rise in the evening sky around late September and remains visible until April. The optimal viewing period occurs between December and March, when the constellation is high in the sky and easily seen globally.
For those in the Southern Hemisphere, the constellation is also visible during their summer months, though its orientation may appear inverted compared to Northern views. Betelgeuse becomes almost impossible to observe between May and August because it is too close to the Sun in the sky, making it unobservable due to the Sun’s glare.
Visual Characteristics of Betelgeuse
Once Betelgeuse is located, its appearance offers immediate confirmation of the identification. The star’s most striking feature is its unmistakable reddish-orange hue, which is noticeable even to the naked eye. This color is a direct result of its relatively cool surface temperature, approximately 3,600 Kelvin, characteristic of a red supergiant star.
Betelgeuse is classified as a semi-regular variable star because its brightness fluctuates over time. Its visual magnitude typically varies between 0.0 and +1.6, with a primary cycle of around 400 days. This natural pulsation means its brightness can change, occasionally causing it to surpass Rigel in brilliance.