Antares, the rival to Mars

Antares, also known as Alpha Scorpii is a very luminous supergiant star located in the constellation of Scorpius, The Scorpion. Antares is a major star and forms part of the constellation.

Antares is the traditional/proper name for the star, whilst Alpha Scorpii is the Bayer Designation for the star. Typically, the brightest star in the constellation is classified as Alpha. A list of additional names and identifications is in the facts list at the bottom of the page.

Based on the spectral type (M1Ib + B2.5V), Antares's colour is red, which means that the star is one of the colder stars in the Universe, colder than our star.

Antares is the brightest star in Scorpius and the 15th in the night sky based on the Hipparcos 2007 apparent magnitude. Antares is a naked eye star and can be seen on a clear night without binoculars or a telescope.

Antares is a slow irregular variable star. Variable stars are stars whose size and/or brightness changes over time. More details about this star is below.

There are no known exoplanets in orbit around the star. There might or might not be any, but due to their size compared to the star, they'll be tough to spot compared to other smaller stars hence why none have been spotted around a supergiant.

Solar System

Antares is a binary or multiple star system. The list below may not include all the stars, only those that are recorded on this site.

• Antares is the main star in the system and the one that is designated as 'A'. It can also refer to the whole system. Antares is a red main sequence star whose temperature is between -0,001 and 3,500 Kelvin. Antares is a variable star of type Slow Irregular.
• Alpha Scorpii B is a blue main sequence star whose temperature is between 10,000 and 25,000 Kelvin.

Location

The location of the Antares in the night sky is determined by the right ascension (R.A.) and declination (Dec.). These are equivalent to the Longitude and Latitude on Earth. The Right Ascension (Longitude) is expressed in time (hh:mm:ss) and is how far the star is along Earth's celestial equator. If the R.A. is positive, then it's eastwards and vice versa.

The Declination (Latitude) is how far north or south the object is compared to the celestial equator and is expressed in degrees. If the value is positive, it is north of the celestial equator. For Antares, the location is 16h 29m 24.47 and -26° 25' 55.0 .

Based on the location of Scorpius, Antares can be located in the southern hemisphere of the celestial sky. The celestial hemisphere is equivalent to the hemispheres on Earth. Antares is on the Ecliptic. The Ecliptic is the path that the Earth takes as it orbits the Sun. As the Earth is titled, we therefore have Celestial and Ecliptic hemispheres and they can be different for a star.

Physical Properties

Antares Colour, Type and Temperature

Antares spectral type of M1Ib + B2.5V which means its colour and type is red supergiant star. There is no relationship between colour and size. For example, a red star can be large or small. Small stars are more energy efficient than larger stars and live longer.

Antares Temperature

Antares effective temperature is 6,561 Kelvin which is hotter than our own Sun's effective temperature, which is 5,777 Kelvin. A star's size doesn't determine a star's temperature, the majority of the largest and smallest stars in the Universe are red stars. Red stars are also amongst the coolest with only brown dwarf stars cooler.

Antares Luminosity

Luminosity is the amount of energy a star pumps out relative to the amount that our star, the Sun, gives out. Our star, the Sun's value is 1. Antares luminosity figure of 36.154 is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012. The star generates more energy than our star.

Antares Size (Radius)

Antares radius has been calculated as being 680 times bigger than the Sun. The Sun's radius is 695,800km, therefore, the Antares's radius is an estimated 473,144,000.km. If you need the star's diameter, you just need to multiply the radius by 2. Antares radius extends out past Mars, meaning all the inner rocky planets including the Earth would be inside the star if we were on the same orbiting path as we are now.

Magnitude

A number represents a star’s magnitude, whether apparent/visual or absolute. The smaller the number, the brighter the star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Antares apparent magnitude is 1.06, which is a measure of the star's brightness as seen from Earth. Apparent Magnitude is also known as Visual Magnitude.

If you use the 1997 parallax value, Antares' absolute magnitude is -5.28. If you use the 2007 parallax value, Antares' absolute magnitude is -5.09. Absolute Magnitude is the star's apparent magnitude from 10 parsecs or 32.6 light-years. The magnitude assumes nothing is between the object and the viewer, such as dust clouds. To compare different stars' actual brightness, you would best use Absolute rather than Apparent Magnitude.

Antares is visible from Earth without needing binoculars or a telescope. The lower the Apparent Magnitude of a star or other object is, the easier it is to see in the night sky. An object with a magnitude greater than 6.5 cannot be seen without a telescope or other device.

Meteor Showers

There are 1 meteor showers that radiate from a location near Antares during the year.

• Alpha Scorpiids Meteor Shower 21 Apr- 26 May (Peak: 15th May).

Distance from Earth

Antares distance from Earth is 604.01 light-years away from Earth or 185.19 parsecs. If you want that in miles, it is about 3,550,748,511,656,632.276, based on 1 Ly = 5,878,625,373,183.61 miles. The distance is calculated using the parallax from the original Hipparcos data released in 1997 which is 5.40000.

In 2007, Hipparcos data was revised with a new parallax of 5.89000, which puts the Antares distance from Earth as 553.76 light-years or 169.78 parsecs. It should not be taken as though the star is moving closer or further away from Earth. It is purely that the distance was recalculated.

An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. When you use the 2007 distance, Antares is roughly 35,019,394.786 Astronomical Units from the Earth/Sun give or take a few.

Antares Galacto-Centric Distance is 7,243 Parsecs or 23,624.011 Light Years. The Galacto-Centric Distance is the distance from the Antares to the Centre of the Galaxy which is Sagittarius A*.

Travel Time

The time it takes to travel to Antares depends on how fast you are going. U.G. has done some calculations as to how long it will take to go at differing speeds. A note about the calculations, when I'm talking about years, I'm talking about non-leap years only (365 days).

The New Horizons space probe is the fastest one that we've sent into space at the time of writing. Its primary mission was to visit Pluto, which at the time of launch (2006), Pluto was still a planet.

Mach 1 is the speed of sound; Mach 2 is twice the speed. |Before retiring, Concorde was the fastest commercial aeroplane and the only passenger jet that could do Mach 2.

For some small screens, you may need to swipe the table to see the information. If you need an explanation, hover over the bold text. At methods are assuming you have unlimited fuel and travel at a constant speed.

• Walking - 92,840,166,118.76
• Car - 5,305,152,349.643
• Airbus A380 - 504,566,120.211
• Mach 1 - 484,003,217.222
• Mach 2 - 274,269,323.837
• New Horizons - 10,202,216.057
• Speed of Light - 553.76

Variable Type

Antares is a Slow Irregular variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be discovered. Antares brightness ranges from a magnitude of 1.067 to a magnitude of 0.906 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.1340 days.

Radial Velocity and Proper Motion

In simplestic terms, all non-rogue stars, like planets, orbit around a central object, although that is actually not true. Where is the centre of the Solar System. For simplicity it's the central star, such as the Sun. In the case of a star, it's the galactic centre.

The constellations we see today will be different than they were 50,000 years ago or 50,000 years from now.

Proper motion details the movements of these stars and is measured in milliarcseconds. Antares is moving -23.3 ± 0.58 milliarcseconds/year towards the north and -12.11 ± 1 milliarcseconds/year east if we saw them in the horizon.

The radial velocity, the speed at which the Antares is towards the Sun, is -3.50000 km/s with an error of about 0.80 km/s . When the value is negative, the star and the Sun are getting closer to one another; likewise, a positive number means that two stars are moving away. It's nothing to fear as the stars are so far apart they won't collide in our lifetime, if ever.

Antares Fact List

Summary Facts

Primary Name:

Antares

Spectral Type:

M1Ib + B2.5V

Binary or Multiple Star:

Yes

Star Type

: Supergiant Star

Colour:

red

Galaxy:

Milky Way

Constellation:

Scorpius

Celestial Hemisphere:

Southern

Main Star

: Yes

Age

: 0.013 billion years

Age Range

: 0.011 - 0.015 billion years

Visual / Apparent Magnitude

: 1.06

Visible From Earth

: Yes

Absolute Magnitude

: -5.09

Radial Velocity

: -3.50000 ± 0.8 km/s

Eccentricity:

0.0784

Semi-Major Axis

: 6794

Luminosity (Lsun)

: 36.154

Mass (Solars)

: 12.5000 (-11.000 / +14.3000)

Effective Temp. (Kelvin):

6,561

Radius

: 680

Location/Coordinates

Right Ascension

: 16h 29m 24.47

Declination

: -26° 25` 55.0

Galactic Latitude

: 15.06434006 °

Galactic Longitude

: 351.94719547 °

Galacto-Centric Distance:

23,624.011 Light Years / 7,243 Parsecs

Distance from Earth

Parallax

: 5.89000

Light Years

: 553.76

Parsecs

: 169.78

Astronomical Units (A.U.)

: 35,019,394.786

Proper Motion

: (milliarcseconds/year)

Declination

: -23.3 ± 0.58

Right Ascension

: -12.11 ± 1

Miscellaneous Facts

B-V Index

: 1.86

Brightest in Night Sky

: 15th

Variable Star Class

: Pulsating

Variable Star Type

: Slow Irregular

Mean Variability Period (Days)

: 0.134

Variable Magnitude Range

: 0.906 - 1.067

Alternate Names

:

Alpha Scorpii, Alf Sco, HD 148478, EPIC 203350682, TYC 6803-2158-1, HIP 80763, HR 6134, 21 Scorpii A, 21 Sco A, CD-26 11359A, alf Sco