A gigaton is a explosion that equalls to 1 BILLIONE tonz of tnt!

A gigaton is 1000 megatons so it would be destroy an an area the size of Louisiana. But of course there is no such thing as a gigaton for bombs.

IN FACT, there are already 1+ gigaton nuclear weapons. A 1 GT bomb would destroy an area the size of Texas, just with the expansive wave. A 90 GT bomb could change the planet trajectory.

1 gigaton is equal to 1000000000000000 grams. that's 15 zeroes after the 1 so in scientific notation that would be 1 x 10^15

1 gigatonne (Gt) = 1,000,000,000,000 or 1012 kg

"giga" is a prefix used to indicate "billion" or 109. 1 gigatonne = 109 tonnes, or 1,000,000,000 tonnes