The sun is nearly a perfect sphere. Its equatorial diameter and its polar diameter differ by only 6.2 miles (10 km). The mean radius of the sun is 432,450 miles (696,000 kilometers), which makes its diameter about 864,938 miles (1.392 million km). You could line up 109 Earths across the face of the sun, according to NASA. The sun’s circumference is about 2,715,396 miles (4,370,006 km).
The mass of an object tells how much matter it contains, while the volume is how much space it takes up. The Sun has a mass of nearly 2 x 1030 kilograms, which is more than 330,000 times the mass of Earth.
Although these numbers seem huge, the Sun is actually a medium-sized star when compared to other stars in the universe.
It may be the biggest thing in this neighborhood, but the sun is just average compared to other stars. Betelgeuse, a red giant, is about 700 times bigger than the sun and about 14,000 times brighter.
Not only is the Sun the largest object at the center of our solar system, but it also accounts for 99.86% of the solar system’s mass. Of the remaining mass, the majority of it is distributed between the gas and ice giants: Jupiter, Saturn, Uranus, and Neptune.
It’s possible that the sun is even larger than previously thought. Xavier Jubier, an engineer and solar eclipse researcher, creates detailed models of solar and lunar eclipses to determine precisely where the moon’s shadow would fall during the solar eclipse. But when he matched actual photos and historical observations with the models, he found precise eclipse shapes only made sense if he scaled up the sun’s radius by a few hundred kilometers.
Over the following 7.5 billion years, the Sun will expand enough to engulf both Venus and Earth. For a few million years, the Sun will be about 200 times bigger than its current size. For around one billion years, the Sun will remain in the red giant phase before later shrinking back to a white dwarf when nuclear fusion comes to an end at its core.
The total volume of the sun is 1.4 x 1027cubic meters. About 1.3 million Earths could fit inside the sun, according to NASA’s statistics. The mass of the sun is 1.989 x 1030 kilograms, about 333,000 times the mass of the Earth. The sun contains 99.8 percent of the mass of the entire solar system, leading astronomers Imke de Pater and Jack J. Lissauer, authors of the textbook Planetary Sciences, to refer to the solar system as “the sun plus some debris”.
To put those numbers into perspective, the Sun’s radius is double the distance between Earth and the Moon.
This brings to life the huge size of our star. If we were to replace Earth with the Sun, the Moon would only be halfway across the Sun’s diameter.
But the sun’s weight isn’t constant. Over time, the solar wind has carried particles, and thus mass, away from the star. According to astronomer Phil Plait, the sun loses an average 1.5 million tons of material every second to the solar wind.
Meanwhile, in the heart of the star, mass is converted into energy. The powerhouse of the star converts more than 4 million tons of solar material into energy every second, Plait said.
Altogether, Plait estimated that the sun has lost a total of 1024tons of material over its 4.5-billion-year lifetime, or more than 100 times the mass of the Earth. While that sounds like a lot, it’s only about 0.05 percent of the star’s total mass.
Jupiter may be the biggest planet in our solar system, but it falls short when compared to the Sun. Jupiter’s radius is 43,411 miles (69,863 km), which is why Jupiter will never become a star. At this size, 1,000 Jupiters or Jupiter-sized planets can fit inside the Sun.
On the other hand, Mercury, the smallest planet in our solar system, has a radius of only 1,516 miles (2,439 km). At this size, 21.2 million Mercurys can fit inside the Sun.
Stars generally get bigger as they grow older. In about 5 billion years, scientists think the sun will start to use up all of the hydrogen at its center, according to NASA. The sun will puff up into a red giant and expand past the orbit of the inner planets, including Earth. The sun’s helium will get hot enough to burn into carbon, and the carbon will combine with the helium to form oxygen. These elements will collect in the center of the sun.