Yep it looks just like a triangle in the middle of the sky at say 9-10 EST.
Comet 17P/Holmes has been relentlessly expanding since its explosion on Oct 23rd and now it spans an angle in the sky almost half as wide as the full Moon. Using a picture of the comet he took on Oct. 30th, Helmut Groell of Moers, Germany, created this animation for comparison:
Actually, the comet is even bigger than it looks. While the Moon is a mere 240 thousand miles away, Comet Holmes is 150 million miles from Earth. The comet's physical diameter is thus seven times wider than the planet Jupiter--and it is still expanding.
co·ro·na (k-rn)
n. pl. co·ro·nas or co·ro·nae (-n)
1. Astronomy
a. A faintly colored luminous ring appearing to surround a celestial body visible through a haze or thin cloud

Originally posted by Hal9000
reply to post by Xeros
Actually, I think the correct term is Coma and not Corona.
But I'll have one just the same.![]()
So the diameter of the gas around the comet is about 1/5th the distance to the Moon!
Pretty good for a comet that was estimated to have a diameter of only 2.11 miles to start with!