Why is the Gregorian Calendar useless for astronomy?

Question

what is calender being followed now?

Answer 1

It lacks the year zero.

"In sixth century Europe, the concept of "zero" was still unknown. Thus, the year 1 BC was followed by the year AD 1."

"The "astronomical" dating system refers to an alternative method of numbering years. It includes the year "0" and eliminates the need for any prefixes or suffixes by attributing the arithmetic sign to the date. Thus, the astronomical date for 2000 CE is simply +2000 or 2000. The astronomical year 0 corresponds to the year 1 BCE, while the astronomical year -1 corresponds to 2 BCE. In general, any given year "n BCE" becomes "-(n-1)" in the astronomical year numbering system. Historians should take care to note the numerical difference of one year between "BCE" dates and astronomical dates."

"Year Dating Conventions" : http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/dates.html

Answer 2

It is a ridiculous statement that it is a useless calendar. The primary purpose of all calendars has always been astronomy, and if this calendar were useless, then why would it have been adopted in the first place and now be in such wide use?

Answer 3

Read the article about 1582 and the Julian calendar and the Gregorian calendar. This may answer your question. Do I get a best answer for this one? :-)

http://en.wikipedia.org/wiki/1582