Antares is the distinctive reddish star that marks the heart of the constellation Scorpius. Located around 550 light-years away, it is one of the brightest stars in the night sky and is easily recognizable by its striking red-orange color. Here are some interesting facts about Antares.
How to Find Antares in the Night Sky
Antares is best seen from the Northern Hemisphere during summer, when it appears low in the southern sky during the evening. If you can recognize the distinctive Teapot of Sagittarius, look immediately to its west for Scorpius. Antares is the bright reddish-orange star near the center of the Scorpion, with its long hooked tail curving away toward Sagittarius.
The Bright Red Heart of Scorpius
Antares is the brightest star in Scorpius and appears near the center of the constellation, marking the heart of the Scorpion. Its reddish-orange color makes it particularly easy to recognize. Antares is also an irregular variable star whose brightness changes over time, ranging roughly between magnitudes +0.6 and +1.4, although it remains easily visible to the naked eye.
Its Name Means “Rival of Mars”
The name Antares comes from the ancient Greek for “rival of Ares,” with Ares being the Greek god equivalent of the Roman Mars. The name refers to the star’s striking reddish color, which can make it resemble Mars when the two appear near each other in the sky. Antares is actually much redder than most naked-eye stars, a result of its relatively cool surface temperature.
Hundreds of Times Wider Than the Sun
Antares is one of the largest stars visible to the naked eye, with a radius roughly 700 times that of the Sun. If it were placed at the center of our Solar System, its surface would extend beyond the orbit of Mars. Despite its enormous size, Antares contains only around a dozen times the Sun’s mass. It is thought to have begun life with around 15 solar masses, meaning it has already shed material equivalent to roughly three times the entire mass of the Sun into space.
A Binary with a Hot Blue Companion
Antares is actually a binary star system consisting of the enormous red supergiant Antares A and a much smaller companion known as Antares B. Unlike its cool reddish companion, Antares B is a hot blue-white main-sequence star with a surface temperature of around 18,000 K (32,000°F). It is around three times more massive than the Sun and lies hundreds of astronomical units from Antares A, meaning the two stars are separated by many times the distance between the Sun and Pluto. Despite being a powerful star in its own right, Antares B is difficult to see because it is overwhelmed by the glare of its enormous companion.
Cooler Than the Sun — But Far More Luminous
Antares has a surface temperature of around 3,500 K (5,800°F), compared with about 5,800 K (10,000°F) for the Sun. This relatively low temperature gives Antares its distinctive red-orange color. Yet because the star is so enormous, its vast surface area allows it to radiate tens of thousands of times more energy overall despite being much cooler than the Sun.
Only Around 10 Million Years Old
Despite its enormous size, Antares is only around 10 million years old, making it hundreds of times younger than our 4.6-billion-year-old Sun. Antares has evolved so much faster because of its much greater mass: massive stars burn through their nuclear fuel far more quickly than smaller stars, allowing Antares to reach the red supergiant stage at a remarkably young age.
Destined to Explode as a Supernova
Antares is already approaching the end of its relatively short life and will eventually explode as a supernova. Exactly when this will happen is impossible to predict, and it could still be hundreds of thousands of years away. When the star finally exhausts the nuclear fuel in its core, gravity will cause the core to collapse, triggering one of the most powerful explosions in the universe. The collapsed core will then remain behind as either a neutron star or, if sufficiently massive, a black hole.
A Star With Thousands of Years of Cultural History
Antares has attracted attention for thousands of years, with its striking red color inspiring different names and stories around the world. Ancient Chinese astronomers knew it as the Fire Star, while Arabic astronomers called it Qalb al-Aqrab, meaning “Heart of the Scorpion.” In Greek mythology, Antares lies at the heart of Scorpius, the giant scorpion associated with the death of Orion the hunter.
Remarkably, Aboriginal Australian oral traditions from South Australia also appear to preserve observations of Antares changing in brightness. In one tradition the star is associated with Waiyungari, whose changing brightness plays a role in the story. Modern research has argued that these traditions encode naked-eye observations of the real variability of Antares.