The Size of Our Sun Compared to the Biggest Stars in the Milky Way Galaxy
When it come to size our Sun is small when compared to the size of the some of the other stars in our galaxy. It is large with respect to the size of Earth and the other planets in the Solar System. However, you will be surprised how small the Sun really is when it is compared to some of the largest stars in the Milky Way Galaxy.
Facts About the Sun
The Sun is the largest object in the Solar System and contains about 99.866 % of the total mass of this system. The other 0.134% of the Solar System mass is contained mostly in Jupiter while the other seven planets contain the remaining mass. From a size perspective, the Sun is 10 times larger than Jupiter and about 100 times larger than Earth as measured by its diameter.
The Sun as described is a main sequence star because of the type of fuel it is burning. It burns hydrogen as its predominant fuel. That is, it follows a predictable life cycle where its mass and size along with its luminosity (color) varies as it ages. Note, all stars do not follow this life cycle. According to the H-R diagram or Hertzsprung-Russell diagram our Sun is a yellow star. The Sun is yellow because it is emitting all the color photons of light at the same time but it emits a little more of it as yellow photons. On the other hand, red stars appear red because they are emitting predominantly red photons but they are also emitting the photons in other colors and are cooler than the Sun. They are emitting light at a longer wavelength and lower energy level.
Also according to the diagram, our Sun is now enjoying its middle age as far the age of the Sun is concern. So it has a long way to go before it finally dies out. Here are nine stars with a few bits of facts astronomers have found to be much larger and brighter than our Sun.
Sirius A, the Dog Star
The first is Sirius A star, also called Alpha Canis Majoris A, the Dog Star; is located about 9 light years from here. It is a little more than two times the size of the Sun which makes Sirius the brightest star in night sky because of its proximity to our system. It is a main sequence bluish-white dwarf star similar to our the Sun but brighter and hotter. It main sequence lifetime is about 1 billion years and is currently 300 million years into its life cycle. So that means it will burn out in about 700 million years. For comparison, the Sun’s main sequence lifetime is about 14 billion years. The Sun is already more than 4 billion years into it life cycle. We will be here for a while.
Pollux is a red-orange, giant star located in the Gemini constellation. It is larger than Sirius A and located about 34 light years from here. It is 10 times bigger than our Sun. Because of it size it is the 17th brightest star in our night sky and is 32 times brighter than our Sun. Pollux is not a main sequence star but falls in the category of red giants. Therefore, its life cycle is completely different from that of the Sun. If Pollux was switched in place of our Sun our planet would be a hot molten rock if not consume by the intense heat. There would be no life here.
Arcturus, another red-orange, giant star; is located almost the same distance as Pollux is from us. It is about 37 light years from here and is the brightest star in the Bootes constellation. It is 25 times bigger than the Sun and because of its size it is the 4th brightest star in the night sky. Arcturus was once a main sequence star that is now in the sequence of the red giants.
Aldebaran, one of two stars in the binary star system, is 65 light years away from Earth in the Taurus constellation. It is an orange-red giant with a diameter as high as 52 times the size of the Sun and is about 150 times as bright as the Sun. This star was once a part of the main sequence star group. These stars are really getting large now.
Rigel, the first of the supergiant stars is about 773 light years away. It is the 6th brightest star in the night sky located in the most familiar constellation called Orion. You will see it as blue-white star. Rigel is 85,000 times as bright as the Sun and is 70 times larger than the Sun. The radiation from this star is 66,000 times more powerful than the Sun’s radiation output due to its output of other radiations besides visible light.
Pistol Star, the first of the blue hypergiants , is much larger than Rigel. This star is 25,000 light years away and is located near the center of the Milky Way. It is estimated that this star emits light 10 million times brighter than the Sun and holds the title as the brightest known star in galaxy. This star has a diameter of about 93 million miles. It would fill the space between the Sun and Earth if one edge of it was placed at the center of the Sun while the other edge would reach the center of the Earth.
Antares A, another red supergiant star, is 600 light years away. This is the point where we are really beginning to see the largest stars in the galaxy. It is the 16th brightest star in the night sky and is 10,000 brighter than the Sun. Antares is almost 430 times larger than the Sun. If it was placed at the center of the Solar System it size would extend beyond the orbit of Mars
Mu Cephei, sometimes called the Garnet Star because it gives off a deep red color in the night sky. This is one of the largest star you can see with your naked eyes despite it estimated 1,550 light year distant from us. However, some astronomers have estimated this distant of this star as far as 5,000 light years because it is difficult to get an accurate measurement of the distant of stars this far out from us. Despite its distant it is one of the brightest red supergiant stars out there. It is 38,000 times brighter than the Sun. This star is 1,650 times larger than our Sun and If it was placed at the center of our Solar System it would fill the Solar system beyond the orbit of Jupiter.
VY Canis Majoris
Finally, the last star in the list is VY Canis Majoris. It is the largest of the known stars discovered so far. This star is considered a red hypergiant star since it is so large. It is 4,900 light years from Earth with a diameter of 1.7 billion miles. If it was placed at the center of our Solar System it would fill the Solar System beyond the orbit of Saturn. Because of it massive size this star is expected to die in about 100,000 years as a hypernova. Fortunately, we will be safe from this explosion since we are so far from it. This star can be spotted in the constellation Canis Major (the “greater dog” in latin) along with the Sirius, the dog star.
As you can see, there are a lot of stars much larger than the Sun out there. All of these stars are located just in our Milky Way. It is not difficult to imagine that there are probably larger stars than these mentioned here in other parts of the Milky Way and in other galaxies. There are a lot of big objects out there yet to be seen. Be aware of the fact that with the Hubble Space Telescope we are just beginning to see other stars beyond the Milky Way Galaxy in our nearest next door neighbor, the Andromeda Galaxy. This galaxy is 2.5 million light years away.
Watch the videos above to see the comparison of the size of our sun to these stars. These videos illustrate these comparisons very well with some very good music accompanying the animation. The first video is the better of the two videos. Enjoy.
© 2011 Melvin Porter
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