Betelgeuse, a luminous red supergiant star, is one of the most recognized objects in our night sky. Its striking reddish hue and prominent position make it easily observable, drawing the attention of sky-watchers for centuries. Classified as a red supergiant, it is nearing the end of its life cycle and has expanded considerably. Betelgeuse has also garnered public interest due to its notable dimming events, which occasionally prompt discussions about its evolutionary state.
Finding Betelgeuse in the Night Sky
Locating Betelgeuse is straightforward once you identify the constellation Orion, its celestial home. Orion, often recognized by its distinctive “belt” of three bright stars in a line, is a prominent constellation. These three belt stars—Alnitak, Alnilam, and Mintaka—form a striking pattern that serves as a guide.
To find Betelgeuse, first locate Orion’s Belt. Then, look for the bright, reddish star positioned above and to the left of the belt from a Northern Hemisphere perspective. This star marks Orion’s right shoulder. Its distinct orange-red color makes it stand apart from other stars in Orion, such as the bluish-white Rigel, which marks Orion’s foot. Its distinct color and brightness make Betelgeuse visible even in areas with some light pollution.
Betelgeuse is best viewed during the Northern Hemisphere’s winter months, from mid-September to mid-March, with optimal observations typically occurring in mid-December. During this period, Orion rises in the east shortly after sunset, appearing higher in the sky as winter progresses. As spring approaches, Orion rises later, making it visible only late at night or in the early morning hours during summer.
Betelgeuse’s Place in the Cosmos
The star is situated approximately 640 to 724 light-years away from Earth. This distance means the light we observe from Betelgeuse today originated from the star hundreds of years ago.
A light-year is a unit of distance, not time, representing the distance light travels in one Earth year. Light moves at about 186,000 miles (300,000 kilometers) per second. Therefore, one light-year is approximately 5.88 trillion miles (9.46 trillion kilometers). Using light-years helps astronomers describe the immense distances between celestial objects in a more manageable way.
Betelgeuse resides within our own galaxy, the Milky Way. Specifically, it is located in the Orion Arm, also known as the Orion Spur or Local Arm. The Milky Way is a spiral galaxy with several arms, and our solar system, along with Betelgeuse, is positioned within one of these smaller arms. This placement means Betelgeuse is relatively close to us on a galactic scale, considering the Milky Way spans about 100,000 light-years across.