Antares: Red Star Next to the Moon
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.
June 27: Antares near the Moon
- Occultation start: 13:06 UTC/GMT (9:06 AM ET)
- Occultation end: 17:21 UTC/GMT (1:21 PM ET)
- Close approach time: 15:10 UTC/GMT (11:10 AM ET)
- Conjunction time: 15:17 UTC/GMT (11:17 AM ET)
- Close approach & conjunction distance: 0°26'
On June 27, the 90%-lit Moon will pass close to Antares. Both objects will rise around sunset and reach their highest point in the sky by evening. A lunar occultation of Antares will be visible from far southern latitudes, mainly across the southern Indian Ocean south of Africa and Madagascar, parts of Antarctica and the surrounding Southern Ocean, and near the southern tip of South America. During an occultation, the Moon passes directly in front of the star, so Antares briefly disappears behind the Moon’s edge and then reappears a short time later.
July 24: Antares near the Moon
- Occultation start: 19:36 GMT
- Occultation end: 23:37 GMT
- Close approach time: 21:35 GMT
- Conjunction time: 21:44 GMT
- Close approach & conjunction distance: 0°34′
On July 24, the Moon will pass close to Antares — the brightest star in Scorpius. In July, Scorpius is one of the best constellations to see this month: just look up after sunset, and you’ll see both the constellation and bright red Antares. And if you don’t spot them right away, the bright Moon will serve as a handy guide that night. Both objects are bright enough to be observed with the naked eye.
| City | Best time, local | Moon illumination | Separation | Altitude Moon/Antares |
|---|---|---|---|---|
| New York, USA | Jul 24, 20:50 | 82% | 2°16′ | 21°/23° |
| Los Angeles, USA | Jul 24, 20:27 | 83% | 3°26′ | 26°/29° |
| London, UK | Jul 24, 22:03 | 81% | 1°28′ | 10°/11° |
| Madrid, Spain | Jul 24, 23:50 | 81% | 1°24′ | 19°/21° |
| Rome, Italy | Jul 25, 00:19 | 81% | 1°23′ | 10°/11° |
| São Paulo, Brazil | Jul 24, 18:05 | 81% | 0°32′ | 58°/58° |
| Sydney, Australia | Jul 25, 02:23 | 79% | 3°23′ | 10°/13° |
On the same day, the Moon will briefly hide Antares from view for a short time. This event, called a lunar occultation, will be visible from Antarctica, the South Sandwich Islands, and the Falkland Islands — so the main audience will be penguins and seals.
| City | Occultation visibility, local time |
|---|---|
| Stanley, Falkland Islands | Jul 24, 17:16–18:27 |
| Mount Pleasant, Falkland Islands | Jul 24, 17:16–18:27 |
| Rothera Station, Antarctica | Jul 24, 17:46–18:42 |
| Alfred Faure Station, Crozet Islands | Jul 25, 03:32–04:30 |
August 21: Antares near the Moon
- Occultation start: 02:57 GMT
- Occultation end: 06:53 GMT
- Close approach time: 04:52 GMT
- Conjunction time: 05:02 GMT
- Close approach & conjunction distance: 0°38′
On August 21, the Moon will pass close to Antares. You can start observing right after sunset: at that time, both objects will be at their highest above the horizon. Look for a reddish point of light next to the Moon — it will be visible even to the naked eye.
| City | Best time, local | Moon illumination | Separation | Altitude Moon/Antares |
|---|---|---|---|---|
| New York, USA | Aug 20, 21:30 | 59% | 2°24′ | 15°/17° |
| Los Angeles, USA | Aug 20, 22:20 | 61% | 1°24′ | 15°/17° |
| Mexico City, Mexico | Aug 20, 23:05 | 61% | 1°19′ | 16°/17° |
| Sydney, Australia | Aug 21, 17:55 | 62% | 1°42′ | 79°/80° |
| Melbourne, Australia | Aug 21, 18:20 | 62% | 1°52′ | 76°/77° |
| Tokyo, Japan | Aug 21, 18:55 | 62% | 2°52′ | 26°/27° |
| Singapore | Aug 21, 19:35 | 63% | 3°35′ | 60°/62° |
On the same day, another event will take place: a lunar occultation of Antares. The star will briefly disappear behind the Moon’s disk and then reappear. The event will be visible to a lucky few in Chile, southern Argentina, the Falkland Islands, and Antarctica.
| City | Occultation visibility, local time |
|---|---|
| Río Gallegos, Argentina | Aug 21, 02:41–03:37 |
| Rio Grande, Argentina | Aug 21, 02:38–03:34 |
| Punta Arenas, Chile | Aug 21, 02:39–03:36 |
| Puerto Williams, Chile | Aug 21, 02:36–03:32 |
| Mount Pleasant, Falkland Islands | Aug 21, 02:38–03:31 |
| Stanley, Falkland Islands | Aug 21, 02:38–03:31 |
September 17: Antares near the Moon
- Occultation start: 10:54 GMT
- Occultation end: 14:56 GMT
- Close approach time: 12:53 GMT
- Conjunction time: 13:02 GMT
- Close approach & conjunction distance: 0°35′
On September 17, the Moon will pass close to Antares. In many northern locations, both objects will be visible low in the sky after sunset. Farther south, they may appear much higher in the sky. Closer to the horizon, you’ll also be able to spot Venus, which is approaching its period of greatest brightness.
| City | Best time, local | Moon illumination | Separation | Altitude Moon/Antares | Venus altitude |
|---|---|---|---|---|---|
| New York, USA | Sep 17, 19:29 | 42% | 5°16′ | 18°/18° | 6° |
| Miami, USA | Sep 17, 19:46 | 42% | 5°21′ | 33°/32° | 15° |
| Madrid, Spain | Sep 17, 20:48 | 40% | 3°05′ | 18°/19° | 6° |
| Athens, Greece | Sep 17, 19:57 | 39% | 2°17′ | 20°/21° | 7° |
| Lisbon, Portugal | Sep 17, 20:09 | 40% | 3°14′ | 19°/20° | 7° |
| Perth, Australia | Sep 17, 20:25 | 37% | 0°58′ | 45°/46° | 11° |
| Singapore | Sep 17, 20:30 | 37% | 1°14′ | 41°/42° | 11° |
| Johannesburg, South Africa | Sep 17, 18:25 | 39% | 1°34′ | 71°/69° | 34° |
On the same day, the Moon will occult Antares. This one is for a very select audience: mainly Antarctica, plus Tasmania and a small part of southern Australia, where the event will happen quite low above the horizon.
| City | Occultation visibility, local time |
|---|---|
| Melbourne, Australia | Sep 17, 23:58–Sep 18, 00:48 |
| Adelaide, Australia | Sep 17, 23:36–Sep 18, 00:21 |
| Casey Station, Antarctica | Sep 17, 21:08–22:13 |
| Heard Island | Sep 17, 17:59–18:49 |
October 14: Antares near the Moon
- Occultation start: 18:56 GMT
- Occultation end: 23:15 GMT
- Close approach time: 21:02 GMT
- Conjunction time: 21:09 GMT
- Close approach & conjunction distance: 0°25′
On October 14, a thin crescent Moon will appear close to Antares. The reddish star will be easy to spot with the naked eye near the not-too-bright Moon, and observers with binoculars may also be able to see the globular star cluster M4 near Antares. Mercury and Venus will also be visible in the twilight sky, mainly for the Southern Hemisphere locations. Start observing after sunset, and try to find a spot with an unobstructed western horizon so you can see the planets along with the Moon and Antares.
| City | Best time, local | Moon illumination | Separation | Altitude Moon/Antares | Altitude Mercury/Venus |
|---|---|---|---|---|---|
| Los Angeles, USA | Oct 14, 18:46 | 19% | 2°16′ | 16°/16° | 5°/Below horizon |
| Miami, USA | Oct 14, 19:18 | 18% | 1°17′ | 22°/22° | 8°/Below horizon |
| Buenos Aires, Argentina | Oct 14, 19:24 | 18% | 0°16′ | 44°/44° | 21°/12° |
| Montevideo, Uruguay | Oct 14, 19:17 | 18% | 0°16′ | 44°/44° | 21°/11° |
| Santiago, Chile | Oct 14, 20:09 | 18% | 0°37′ | 45°/44° | 21°/11° |
| Bogotá, Colombia | Oct 14, 17:48 | 18% | 1°00′ | 38°/38° | 18°/6° |
| São Paulo, Brazil | Oct 14, 18:55 | 17% | 0°29′ | 38°/38° | 14°/4° |
| Rio de Janeiro, Brazil | Oct 14, 18:40 | 17% | 0°35′ | 38°/38° | 14°/4° |
On the same day, the Moon will also occult Antares: the star will temporarily disappear behind the lunar disk. The visibility area includes eastern Uruguay, southern Brazil, South Georgia and the South Sandwich Islands, and Saint Helena, Ascension and Tristan da Cunha.
| City | Occultation visibility, local time |
|---|---|
| Montevideo, Uruguay | Oct 14, 19:09–19:39 |
| Punta del Este, Uruguay | Oct 14, 19:09–19:42 |
| Chuí, Brazil | Oct 14, 19:16–19:42 |
| Santa Vitória do Palmar, Brazil | Oct 14, 19:17–19:41 |
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!
