What is Antares: A Supergiant Red Star Rivaling Mars
Antares, the “rival of Mars”, is a supergiant star that appears as a bright reddish dot to the naked eye. To easily find Antares in the sky in your exact location, use the free Star Walk 2 app. Read on to learn interesting and useful facts about this star.
Contents
- Antares – key star facts
- Where is Antares in the sky?
- When to see Antares?
- More facts about Antares
- Antares, the rival of Mars: Conclusion
Antares – key star facts
- Official name: Antares, α Scorpii, Alpha Scorpii
- Alternative names: Cor Scorpii, Kalb al Akrab, Scorpion's Heart, Vespertilio
- Catalog designations: 21 Scorpii, HD 148478, SAO 184415, HIP 80763
- Constellation: Scorpius
- Star type: class M1.5Iab-Ib red supergiant
- Right ascension: 16 h 29 m 24.46 s
- Declination: −26° 25′ 55.21″
- Apparent magnitude: from 0.6 to 1.6
- Mass: ≈ 12 solar masses
- Luminosity: 2,754 L
- Radius: ≈ 680 solar radius
- Surface temperature: 3,500 K
- Distance from the Earth: ≈ 550 light-years
- Rotation period: unknown
How big is Antares?
Antares is one of the largest known stars. It is about 700 times larger in diameter than the Sun. It's also about 10,000 times brighter, although its surface temperature is quite low (about 1.5 times cooler than that of the Sun) – all because of the star’s enormous size. Antares is so large that if it were in the position of our Sun, it would extend beyond the orbit of Mars, and the star’s chromosphere would extend past Jupiter.
Antares color & brightness
Antares is classified as a spectral type M1.5Iab-Ib star. “M1.5” here signifies a temperature of around 3,400˚C. The stars of this temperature appear orange-red. “Lab” is the designation of an intermediate-size luminous supergiant, “Ib” being a less luminous supergiant. Antares is between these designations.
Antares is a variable star, with its visual magnitude changing irregularly from 0.6 to 1.6. It’s the brightest star in the constellation Scorpius and the 15th-brightest star in the whole night sky.
The name Antares is of Greek origin and literally means "rival of Ares", that is, rival of Mars. The star is very similar in brightness and color to the Red Planet. And because of its proximity to the ecliptic, Antares occasionally meets Mars in the sky, making the celestial objects appear together like twin brothers.
Where is Antares in the sky?
Antares is located in the “heart” of the constellation Scorpius. In the Northern Hemisphere, the star is visible south of 63° north latitude. In the Southern Hemisphere, Antares rises high in the sky and is circumpolar from about 63° south latitude.
How to find Antares?
Antares is surrounded by mostly 2nd and 3rd-magnitude stars, so there are no bright stars around to help you navigate. However, if you're in the Southern Hemisphere, you might spot the constellation Scorpius itself, as it's large and distinct. You can also navigate by the Moon or planets when they're near Antares. Read on to find out the upcoming Antares conjunction dates.
Another easy way to find Antares is to use the Star Walk 2 app. Simply search for the star, and follow the arrow on the screen to locate Antares in the sky above you. The app is available for free, but you can subscribe for additional features.
When to see Antares?
Antares is visible almost all year round, except when the Sun passes near it. As a part of the zodiac constellation Scorpius, Antares is hidden while the Sun passes through the constellation from around November 22 to November 29. The star becomes visible again later, reaching its highest point in the night sky from May to August.
Below is the list of upcoming celestial events featuring Antares. You can also find these events through the Star Walk 2 calendar, where you can enable alerts and see how these objects will appear in the sky from your location on the specified dates.
December 23: Mercury and Antares
On December 23, at 21:39 GMT, Mercury and Antares will be 6°48′ apart in the sky. Mercury is about to reach its greatest elongation (the farthest point in the sky from the Sun), so it's a perfect time to see the planet. The pair can be seen with the naked eye about an hour before sunrise.
December 28: Moon and Antares, Lunar occultation of Antares
On December 28, from 13:01 to 17:31 GMT, the Moon will pass in front of Antares. The event will be visible from northeastern French Polynesia.
A close conjunction between Antares and the Moon will be visible worldwide. On December 28, at 14:37 GMT, the two objects will appear just 0°06′ apart. You can spot them together in the constellation Scorpius. The Moon will be in a waning crescent phase, making it hard to spot. Antares, the brightest star in Scorpius, will be easily visible.
January 24, 2025: Moon and Antares, Lunar occultation of Antares
On the night of January 24-25, from 21:56 to 02:22 GMT, the Moon will pass in front of Antares. This event will be visible in countries like Madagascar, Maldives, Mauritius, and Réunion.
The rest of the world will see a close conjunction between Antares and the Moon. On January 24, at 23:34 GMT, the two objects will appear just 0°18′ apart. You can spot them together in the constellation Scorpius. The Moon will be two days away from reaching the Full Moon phase, so it will be shining bright. Antares, the brightest star in Scorpius, will also be easily visible.
February 21, 2025: Moon and Antares, Lunar occultation of Antares
On February 21, from 06:45 to 11:01 GMT, the Moon will pass in front of Antares. This event will be visible in Argentina, Chile, Uruguay, and the Falkland Islands.
The rest of the world will see a close conjunction between Antares and the Moon. On February 21, at 08:21 GMT, the two objects will appear just 0°30′ apart. You can spot them together in the constellation Scorpius. The Moon will be in its Last Quarter phase, shining bright. This is a great opportunity for astrophotography!
March 20, 2025: Moon and Antares, Lunar occultation of Antares
On March 20, from 14:23 to 18:35 GMT, the Moon will pass in front of Antares. This event will be visible in Australia, Antarctica, New Zealand, and Tasmania.
The rest of the world will see a close conjunction between Antares and the Moon. On March 20 at 15:58 GMT, the two objects will appear just 0°30′ apart. They can be seen together in the constellation Scorpius. The Moon will be 72% illuminated and Antares (mag 1.1) will shine brightly nearby.
More facts about Antares
The life cycle of Antares
Antares is a red supergiant, which means it is in the final stages of its life cycle. One day it will run out of fuel and collapse, possibly causing a supernova that we could see from the Earth. We don't know exactly when it will happen – it could be tomorrow or millions of years from now. But when it does, it's going to be an amazing show in the sky!
Want to know more about the life of stars? Here is our fun infographic – check it out!
Antares B: the lesser-known companion
Antares is, in fact, a binary star system, consisting of the red supergiant Antares A and the blue-white main sequence star Antares B. Antares B, situated approximately 2.5 arc seconds west of Antares A, was first observed in 1819 by astronomer Johann Tobias Bürg when Antares A was obscured by the Moon.
Antares B shines with a magnitude of 5.5 and has a blue-white hue, though it appears greenish due to the influence of orange-red Antares A. To catch a glimpse of Antares B, you'll need a telescope with an aperture of 8 inches and a magnification of 200x.
Antares name in different cultures
Different cultures have different names for the star and its constellation. We already know the Greek name, which means "rival of Ares". In ancient China, Antares was called the Fire Star and was part of a dragon constellation. In Hawaiian stories, the constellation represents a fishing hook used by the hero Maui to lift the islands out of the sea. Antares (Lehua Kona) sits just above the point of the hook. In addition, both the Arabic and Latin names for the star translate to "heart of the scorpion".
Antares, the rival of Mars: Conclusion
Antares is a bright orange-red star in the constellation Scorpius. It’s best seen from the Southern Hemisphere, but can also be spotted in the Northern Hemisphere. To easily locate Antares, try the free Star Walk 2 app or observe it near the Moon or planets.
Wishing you clear skies and happy stargazing!
