Chris, thank you for your question.
No, I haven’t heard of a discrepancy between
the Gregorian and Vedic calendars — mainly
because there’s no such thing as a Vedic
Your friend is confusing two unrelated issues:
the differences between the Julian and Gregorian
calendars and the difference between the Tropical
and Sidereal Zodiac.
There’s a third issue here, too — a distortion
of a completely unfounded argument used by
scientists and skeptics to attempt to discredit
astrology, which is what your friend was trying,
very unsuccessfully, to do.
First, let’s address the issue of the calendars.
The Julian Calendar, proposed by Julius Cesar
in 46 BC was a revision of the Roman calendar,
and it became the standard calendar in the
entire Roman empire.
The Julian calendar attempted to align the
calendar year with the tropical year. It consisted
of twelve months, 365 days, and a leap day
in February every four years.
The problem with the Julian calendar is that
it’s not entirely exact. The tropical year
is actually a little bit shorter than 365
¼ days, which means that the Julian calendar
gains about three days every four centuries
and no longer tracks with the tropical year.
This error was corrected in 1582 with the
introduction of the Gregorian calendar, which
eliminates Leap Year in years evenly divisible
by 100, although years evenly divisible by
400 remain Leap Years. That’s why the year
1900 was not a leap year, but the year 2000
It took quite some time for the world to get
on board with the Gregorian calendar, but
by the mid 20th Century everyone was using
it (although some branches of the Eastern
Orthodox Church still use the Julian calendar
to determine the dates for Easter each year).
The calendar difference is mainly significant
when looking at historical documents or when
considering historical charts.
Usually dates in these documents will be noted
as either O.S. for Old Style Julian date,
or N.S. for New Style, Gregorian date.
Currently, the Julian calendar is 13 days
behind the Gregorian calendar.
Astrology charts are always calculated based
on the visible and/or measurable positions
of the planets, not based on calendar dates.
Calendar dates are only used in popular Sun
Sign horoscope columns as a rough guideline
to determine the position of the Sun in your
As Sun Sign columns have only been around
for about 100 years, the date ranges are all
based on the Gregorian calendar, so for what
it’s worth (and it’s not worth very much),
they’re all correct.
There are, however, two different zodiac systems.
In Western Astrology, we use the Tropical
Zodiac. But Eastern Astrology — which includes
Vedic astrology — uses the Sidereal Zodiac.
Astrology measures the relative longitudinal
positions of the planets around the great
circle of the ecliptic. To measure a position
along a circle, you have to define a starting
point. In astrology, that starting point is
known as 0° Aries.
Tropical Astrology takes 0° Aries to be the
moment of the Spring Equinox each year. This
is an objective, observable, astronomical
Because of the wobble of the Earth’s Axis,
the Spring Equinox gradually moves backwards
along the ecliptic.
When our system of astrology was being developed
two thousand years ago, the Spring Equinox
occurred somewhere against the group of stars
that formed the constellation of Aries. But
now, it occurs against the group of stars
that forms the constellation of Pisces.
The Sidereal Zodiac attempts to align 0°
Aries with the beginning of the constellation
of Aries. Currently, there is about a 23°
difference between 0° Aries in the Tropical
Zodiac and 0° Aries in the Sidereal Zodiac.
At this point, it’s important to understand
that the constellations have never had anything
to do with astrology.
The signs of the zodiac take the names and
follow the sequence of the 12 constellations
that cross the ecliptic, but the constellations
have never been used to measure the relative
positions of the planets.
Signs in astrology are units of measurement,
equal to 30° of arc. The constellations have
never divided the ecliptic into equal segments.
Also: constellations don’t actually exist.
You can’t look up in the sky and point to
the start of the constellation of Aries.
The Sidereal Zodiac begins with the Tropical
position of 0° Aries and then uses one of
several different mathematical formulas to
compensate for the precession of the equinoxes.
While there’s a big difference between the
Tropical and Sidereal Zodiacs, there’s also
a big difference in how Western and Vedic
astrologers interpret the meanings of the
planets and signs. If you’re using Western
Astrology, you use the Tropical Zodiac.
You can — and should — ignore any comments,
articles, or Facebook posts that claim to
discredit or debunk astrology.
These include posts that claim that NASA has
discovered a 13th sign, and other variations
that tell you that your sign has suddenly
If you want to know more — and be able to
debunk any and all of these arguments — you
can read my Open Letter to Dr. Neil DeGrasse
Tyson, in the January 2017 issue of Talented