Larry Alexander, age 10, of Huntsville, Alabama, for his question:
Are any stars in the Milky Way bigger than our Sun?
Yes there are. In the teeming Milky Way, our sun rates as a middling sized pumpkin. It is much smaller than a large pumpkin type. A Great Pumpkin type star could swallow a few million sun sized stars and have lots of room for dessert. But this is not important. From our point of view, the sun is the biggest and the most gloriously glamorous star in the Milky Way and also in the whole Universe.
As we know, the stars and other heavenly bodies tend to fool our eyes. For example, our sun looks like the largest of all stars. But this is because it is only about 93 million miles away. There are only about 15 other stars within a range of 60 million million miles. The closest one to the sun is about 27 million million miles away.
In the sky, things diminish with distance as they do on the earth. For example, a building seems to grow taller as we get closer. When we see it from afar, it seems to shrink. Since this is so, we might expect the big bright stars to be neighbors and the small dim ones should be far away. However, we cannot trust this logical idea because, as usual, heavenly bodies tend to fool our eyes.
It so happens that stars vary in size and brilliance. Often a smallish one looks like a whopper, just because it is fairly close. Actually, the biggest star we know about is too dim for our eyes to see. However, we can check a couple of whoppers in Orion. This bright, winter constellation is shaped like a tall, skinny diamond. To measure their distances, let's use the light year which equals almost six million million earth miles.
The star at Orion's foot is Rigel. It is about 42 times wider than our sun and we see it from 650 light years away. At the top of Orion is big Betelgeuse, also at 650 light years. The diameter of this red supergiant is 460 million miles, which is 540 times wider than the sun. The brightest summer star is Antares, in the constel¬lation Scorpio. This supergiant is 330 times wider than the sun and 170 light years away.
The biggest star we know about is located a little higher than Big Betelgeuse, near the bright golden star Capella. Even if it were neaTep, its dim pale light would be lost against the background of the Milky Way. It is not visible so nobody gave it a common name. Astronomers named it Epsilon Aurigae which tells us that it is the 5th brightest star in the constellation Auriga, the Charioteer. The diameter of this enormous star is 3000 times wider than the sun.
Suppose these whopping stars could replace our sun at the center of the Solar System. Antares would spread out beyond the orbit of Mars. Betelgeuse would sprawl out almost as far as Jupiter. Epsilon Aurigae would engulf the orbits of Mercury and Venus, Earth and Mars then spread on out beyond to Jupiter. Its outer edge would be near the orbit of Uranus and Uranus is about 1,800 million miles from our neat¬little, friendly little, medium sized sun.