Genesis 1:14-18, "And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for SEASONS. (emphasis mine)
The following details by Robert Rose explains how by the Mazzaroth, the seasons were to be determined and accordingly, the calendars:
Aries is the first month of Nisan and the symbol is the RAM or passover ram/lamb. The ancients always started the first month in Aries to kill the passover lamb during this time when the sun was in Aries.
Libra is the 7th Month Tirshri and is the symbol of Judgement or Righteous Justice.
The equinox used to start in Aries, but because the "Precession of the Equinox's" they drift back through time and now they start in Pisces.
Stars are the only heavenly bodies that are fixed. The Sun, Moon, Equinox's, Solstice's and Planets move all over the ecliptic and are not fixed. You HAVE TO HAVE SOMETHING THAT IS FIXED IN ORDER TO HAVE A REFERENCE POINT in the heavens.
Since the sun was in Aries when our ancient fathers started Nisan on the New Moon and the Sun was in Libra during the 7th Month new moon and the stars are fixed unlike everything else....
I don't see why we shouldn't be celebrating the appointed feasts of the LORD in their proper season.
Based on all this....
2010 Nisan = May New Moon
2010 Tishri = November New Moon
2017 Nisan = April New Moon
2017 Tishri = October New Moon
So, the actual true Rosh Hashanah (determined by the constellations of the Mazzaroth) may be from November 8th to several days later; depending on the sighting of the new moon.
Please see the previous entry detailing the vast rationales why the Rapture of the readied Bride appears to occur on a Rosh Hashanah:
Noteworthy is the fact that the Arab leaders have given a November 8th deadline to Obama for the Israeli "land for peace" situation to be resolved.