1. Hydrogen (H): This makes up about 70.6% of the Sun's mass. It's the fuel source for nuclear fusion in the Sun's core, converting hydrogen into helium.

2. Helium (He): This makes up about 27.4% of the Sun's mass. It's the product of nuclear fusion, and its presence in the Sun is a testament to the ongoing nuclear reactions happening within.

While these two elements make up the vast majority of the Sun, there are trace amounts of other elements, like oxygen, carbon, and iron.