The same formulae can also be simplified to compute the parameters relative to the Sun: L L ⊙ ⊙ = ( R R ⊙ ⊙ ) 2 ( T T ⊙ ⊙ ) 4 T T ⊙ ⊙ = ( L L ⊙ ⊙ ) 1 / 4 ( R ⊙ ⊙ R ) 1 / 2 R R ⊙ ⊙ = ( T ⊙ ⊙ T ) 2 ( L L ⊙ ⊙ ) 1 / 2 where R ⊙ ⊙ is the solar radius, and so forth. They can also be rewritten in terms of the surface area A and radiant exitance M ∘ ∘ : L = A M ∘ ∘ M ∘ ∘ = L A A = L M ∘ ∘ where A = 4 π π R 2 and M ∘ ∘ = σ σ T 4 .