In a recent Forum article-What is the Aurora? (Eos Trans. AGU, 85(52), 567, 28 December 2004)-John Clarke has raised an important issuec how we define the aurora. I, too, was confronted by the same question when I was writing a review entitled Auroral emissions of the giant planets with Randy Gladstone <Bhardwaj and Gladstone, 2000>. I widely searched the literature then, to find how the aurora should be defined. Finally, we defined the aurora as electromagnetic radiation emanating from the high latitudes of a planet (also called auroral or polar latitudes). We also defined auroras as (generally) high-latitude atmospheric emissions that result from the precipitation of energetic charged particles from a planet's magnetosphere.