Brightest Stars

The brightest stars in the night sky (listed below) are either some of our nearest neighbours or highly luminous stars that lie at greater distances. Sirius, the brightest star in the Earth’s sky, lies only 8.60 light years away and is one of the nearest stars to the Sun. With twice the Sun’s mass and a radius 1.711 times solar, it is 25.4 times more luminous than the Sun. Nicknamed the Dog Star, it lies in the constellation Canis Major.

Other first-magnitude stars (stars brighter than magnitude +1.50) located within 30 light years (9.19 parsecs) of Earth are Alpha Centauri (4.37 ly), Vega (25 ly), Procyon (11.46 ly), Altair (16.73 ly), and Fomalhaut (25.13 ly). Alpha Centauri, the nearest star system to Earth, is the third brightest point of light in the sky outside the solar system, after Sirius and Canopus. It lies in Centaurus constellation. Canopus, the second brightest star, is a highly luminous bright giant located at a distance of 310 light years in the constellation Carina. The giants Arcturus and Capella, the fourth and sixth brightest stars, are both intrinsically luminous and relatively close, at 36.7 and 42.9 light years.

Sirius, Canopus and Alpha Centauri — the three brightest stars in the sky, image: Wikisky

Other than Canopus, the first-magnitude stars that appear exceptionally bright because they are intrinsically luminous include the supergiants Rigel, Betelgeuse and Deneb, which lie approximately 860, 700, and 2,615 light years away respectively. Deneb, a white supergiant, is by far the most distant first-magnitude star. It has a luminosity about 196,000 times that of the Sun and an absolute magnitude of -8.38.

The greatest concentration of exceptionally bright stars is found around the constellation Orion, within 60 degrees of a point in the neighbouring constellation Monoceros (RA: 6h 30s, Dec.: 5° S). There are 11 stars brighter than magnitude 1.6 in this region: Betelgeuse and Rigel in Orion, Pollux and Castor in Gemini, Aldebaran in Taurus, Regulus in Leo, Sirius and Adhara in Canis Major, Procyon in Canis Minor, Capella in Auriga, and Canopus in Carina. Six of them – Sirius, Procyon, Pollux, Capella, Aldebaran and Rigel – form a prominent northern winter asterism known as the Winter Hexagon or Winter Circle. The red supergiant Betelgeuse, which lies near the centre of the asterism, forms a pattern known as the Winter Triangle with its bright neighbours Sirius and Procyon.

Brightest stars, image: Wikisky

Familiar star patterns like the Winter Circle make it easy to identify the stars and to find any deep objects that lie in the vicinity. Other asterisms containing first-magnitude stars include the Southern Cross, the Summer Triangle, and the Spring Triangle.

Largely invisible to northern observers, the Southern Cross is formed by the first-magnitude Acrux and Mimosa with Gacrux, Imai and Ginan. Commonly used to find the south celestial pole, the asterism is easily recognized both because it is bright and because it lies next to Alpha and Beta Centauri (Hadar), the third and 11th brightest stars in the sky.

Brightest southern stars, image: Wikisky

Visible high overhead during the northern hemisphere summer, the Summer Triangle is formed by Deneb, Altair and Vega, the brightest stars of Cygnus, Aquila and Lyra constellations. The Northern Cross, formed by the brightest stars of Cygnus – Deneb, Sadr, Albireo, Aljanah and Fawaris – lies within the larger triangle asterism.

Brightest northern stars, image: Wikisky

The Spring Triangle has its vertices at Arcturus, Spica and Regulus, the luminaries of the constellations Boötes, Virgo and Leo. Regulus is also part of the Sickle of Leo, an asterism that appears as a backward question mark and outlines the mane of Leo, while Arcturus and Spica also form the Great Diamond with Cor Caroli, the brightest star in Canes Venatici, and Denebola at the tail of Leo. Arcturus and Spica are easily found using the stars of the Big Dipper. The arc of the Dipper’s handle leads first to Arcturus and then to Spica. Arcturus is the fourth brightest star in the Earth’s sky, Spica the 16th, and Regulus the 22nd.

The three brightest stars in the sky – Sirius, Canopus and Alpha Centauri – all lie in the southern celestial hemisphere. While Sirius is visible from all but the northernmost locations (the Arctic Circle), Canopus never rises for observers living north of the latitude 37° 18’ N and Alpha Centauri is invisible to those north of the latitude 29° N. Other than Sirius, the brightest visible stars from locations in mid-northern latitudes are Arcturus, Vega and Capella, the three brightest stars of the northern sky. Achernar, the ninth brightest star, and Hadar, the 11th, never rise for observers in mid-northern latitudes. Achernar marks the end of the river in Eridanus constellation and Hadar is one of the two Southern Pointers, along with Alpha Centauri, in the constellation Centaurus.

The brightest stars in the sky change over time. Sirius became the brightest star about 90,000 years ago, taking over from Canopus, and will keep the title for another 210,000 years, when Vega takes over. Sirius will reach its maximum brightness at magnitude -1.64 in about 60,000 years, when it comes within 7.8 light years of the Sun.

Canopus was the brightest star in the sky three times in the last 5 million years and will be the brightest star again in 480,000 years, when it takes over from Vega. It will be succeeded by Menkalinan (Beta Aurigae) in about 990,000 years.

The brightest of the historical brightest stars in the last five million years were Adhara (Epsilon Canis Majoris), which peaked at magnitude -3.99 about 4,700,000 years ago, Mirzam (Beta Canis Majoris) which shone at magnitude -3.65 about 4,420,000 million years ago, Ascella (Zeta Sagittarii), which reached magnitude -2.74 about 1,200,000 years ago, Zeta Leporis, which peaked at magnitude -2.05 about 1,050,000 years ago, and Canopus (Alpha Carinae), which reached a visual magnitude of -1.86 about 3,110,000 years ago, when it came within 177 light years of the solar system. The bright giant has since moved to a distance of 310 light years and is still the second brightest star in the sky. Even though it is moving away, it will be the brightest star in the Earth’s sky once again and peak at magnitude -0.40 in 480,000 years, when it moves to a distance of 346 light years from Earth.

Historical brightest stars, image: Wikimedia Commons/Tom Ruen

The only star that will shine brighter than Sirius in the next 5 million years is Delta Scuti, which will peak at magnitude -1.84. Currently located 202 light years away, the variable giant will succeed Menkalinan as the brightest star in about 1,150,000 years, when it comes within 10 light years of the solar system (if it maintains its current course and brightness). Delta Scuti will be succeeded by Eltanin (Gamma Draconis) in about 1,330,000 years, and Eltanin will reach its peak magnitude of -1.39 in 1,550,000 years, when it comes within 27.7 light years of the Sun. (Currently, it is 154.3 light years away.)

Even looking at the present alone, there is no definite list of the brightest stars in the sky. Different sources may give slightly different values for stars’ apparent magnitudes, and the stars themselves can vary in brightness, sometimes outshining other stars that are normally brighter and at other times dimming below their usual brightness.

Almost a half of the first-magnitude stars vary in brightness, if only very slightly. Vega (mag. -0.02 to 0.07), Capella (mag. 0.03 to 0.16) and Rigel (mag. 0.05 to 0.18), the sixth, seventh and eighth brightest stars respectively, occasionally trade places, and Aldebaran (mag. 0.75 to 0.95), Antares (mag. 0.6 to 1.6) and Spica (mag. 0.97 to 1.04), the 14th, 15th and 16th brightest stars, can appear equally bright. Other variable first-magnitude stars are Achernar (mag. 0.40 to 0.46), Betelgeuse (mag. 0.0 to 1.6), Deneb (mag. 1.21 to 1.29), and Mimosa (Becrux, mag. 1.23 to 1.31).

LIST OF BRIGHTEST STARS

Below is the list of the 300 brightest stars in the sky. The apparent magnitude data is taken from the Hipparcos catalogue, even if more recent sources give slightly different values. Also provided are the stars’ Bayer or catalogue designations, distances, spectral classes and proper names. The names placed in brackets are the stars’ traditional names that have not been officially approved by the International Astronomical Union (IAU).