Heliocentric Chart vs Geocentric: How Often Signs Differ

The kundli engine and sign tables on this site all work from the centre of the Earth: the planets are placed where an observer there would see them against the zodiac. A heliocentric chart moves that observer to the centre of the Sun and places the same planets again. The English Wikipedia article on heliocentric astrology describes it as a method its users combine with the geocentric chart rather than a replacement for it, and states plainly that most forms of astrology are geocentric. Jyotish, as every calculator on this site computes it, is one of them. The figures below come from the JPL DE421 ephemeris, read once from the Earth and once from the Sun for every day from 1950 to 2050, so the difference between the two charts can be measured rather than described.

What Moves When the Centre Moves

The Sun drops out and the Earth comes in. From the Sun’s centre there is no Sun to place, but there is an Earth, and it lies opposite the Sun of the geocentric chart: on the worked date below, the geocentric Sun is in tropical Scorpio and the heliocentric Earth in Taurus. The generator behind this page tested that on all 36,890 days of the census, and the Earth seen from the Sun never strayed from the geocentric Sun plus 180° by as much as a hundred-thousandth of a degree.

The Moon is left out. The generator gives it no heliocentric row, and this page prints none.

Houses, ascendant and midheaven go. All three are built from a place and a time on the Earth’s surface. The Wikipedia article notes that a heliocentric chart has none of them, because there is no location on the Sun to compute houses for. What is left is a ring of planets in signs. The same article dates the idea back to Copernicus and names Andreas Aurifaber as the first astrologer to consider applying the heliocentric model.

How Often the Two Signs Differ, 1950–2050

Sampled at noon IST on each day, the share of days on which a planet’s heliocentric sign is not its geocentric sign, the mean and largest angle between the two directions, and the share of days on which the geocentric planet moves backwards:

Each of the first three columns of figures falls planet by planet outward from the Sun, in both zodiacs. Switching from tropical to Lahiri signs moves any share by less than 0.8 percentage points, which is expected: the ayanamsa shifts both longitudes by the same amount, so only the position of the sign edges changes. The order has two different causes, one for the planets inside the Earth’s orbit and one for those outside it.

Mercury and Venus. From the Earth these two keep to the Sun’s part of the sky. In the site’s DE421 Lahiri sign tables for 1950–2050, Mercury is never more than 1 sign from the Sun’s sign, Venus never more than 2. From the Sun, by contrast, both run through all twelve signs within 2027 alone. When either passes between the Earth and the Sun, the two views look in opposite directions, which is where the largest angle of 180.0° comes from. Their signs differ on 88.5% and 85.8% of days, close to but below the 91.7% that two unrelated twelve-way labels would give.

Mars and beyond. For a planet outside the Earth’s orbit, the two directions differ only by how far the Earth stands off the Sun as seen from that planet, and that angle shrinks with distance. If both orbits were circles, the widest possible gap would be the angle whose sine is one astronomical unit divided by the planet’s mean distance; with real ellipses the sine can grow to the Earth’s farthest distance over the planet’s nearest. The orbit sizes in the site’s planetary engine bracket each measured maximum:

So Mars, never more than 47.4° out, still sits in a different sign on 73.2% of days, nearly three days in four; Jupiter on 25.0%, about one in four; and from Saturn outward the share stays under one day in seven, down to 3.6% for Pluto, whose largest angle (2.0°) equals Neptune’s. From Saturn outward the two directions are never more than 6.4° apart, so the two signs can differ only while the planet is within that distance of a sign edge; the shares 12.7%, 6.6%, 4.0% and 3.6% measure how often a sign edge falls between the two directions.

Retrograde. The last column has no heliocentric counterpart. Every daily heliocentric step of every planet in the census is forward; the generator refuses to write its file otherwise. Backward motion is something the Earth’s own movement adds to the view, and the outer planets show it on a larger share of days the farther out they are, from 9.6% for Mars to 43.6% for Pluto. The geocentric station dates are listed on the retrograde planets 2026 page, and the Uranus, Neptune and Pluto sign dates page gives the geocentric sign changes of the three slowest planets, loops included.

Sign Entries in 2027: From the Sun and From the Earth

Counting every sign entry dated in 2027: the heliocentric ones from the generator’s table, the geocentric ones from the site’s DE421 Lahiri sign tables, where an entry back into the previous sign during a retrograde loop counts as an entry too.

Mercury and Venus enter more signs from the Sun’s view than from the Earth’s. Mercury’s gap, 49 heliocentric entries in the year against 16 geocentric, is the largest. Across the whole entry table its tropical Aries entries come 13 times between 6 February 2026 and 27 December 2028, one round of the zodiac every 87.9 days on average, which matches the 87.9 days implied by its mean heliocentric motion in the census. The round is not even. Mercury’s orbit has the largest eccentricity in the site’s planetary engine (0.206), and a stay in one sign runs from 5 to 11 days counted date to date: 5 days on every pass through Taurus, Gemini and Cancer, and up to 11 in Scorpio, Sagittarius and Capricorn.

Mars, Jupiter and Saturn go the other way: fewer heliocentric entries, because each of their geocentric counts includes at least one step back into the previous sign. Uranus, Neptune and Pluto change sign in neither chart in 2027. Uranus entered heliocentric tropical Gemini on 10 January 2026 and stays there through 2028; in Lahiri terms it is in Taurus for all three years. Neptune and Pluto have no heliocentric sign change in 2026–2028 in either zodiac. The heliocentric entries of Mars, Jupiter and Saturn in 2027:

These slower planets were sampled once a day at 00:00 IST, so each date above is the first midnight found in the new sign, and the crossing itself falls during the day before. (Mercury and Venus were sampled every hour, so their dates are the crossing day itself, or the next day when the crossing comes in the last hour before midnight.) Saturn’s only heliocentric entry of the year will be the Lahiri one into Aries, by 14 October 2027; tropically it is in Aries all year and will be in Taurus by 26 March 2028. Their geocentric Lahiri sign dates are on the Mars sign by date of birth and Jupiter and Saturn sign by birth year pages; the inner planets have theirs on the Mercury and Venus pages.

One Date Worked Through: 28 October 2026

At noon IST on 28 October 2026, the publication date of this page. Heliocentric signs are read from the entry table, starting from the sign before each planet’s first entry of 2026 (heliocentric motion being forward only), and 10 of them were checked against an independent heliocentric orbit computation from the site’s planetary engine. Geocentric Lahiri signs come from the DE421 tables; geocentric tropical signs of the Sun and Mercury to Saturn come from the engine, used only because each lies at least 0.5° from a sign edge on this date.

Of the 6 planets whose heliocentric sign the data fix, Mercury, Venus and Mars are in different signs in the two charts, in both zodiacs, and Jupiter, Saturn and Uranus keep their sign in both. Mercury’s heliocentric and geocentric signs are 5 signs apart in either zodiac. Neptune and Pluto are marked “not derivable”: they make no heliocentric sign change in 2026–2028, so the entry table cannot say which sign they are in. The census puts each within 2.0° of its geocentric position, but that does not settle the sign, and this page does not guess it.

The table also shows the zodiac question that sits under both charts: tropical and Lahiri names differ in 15 of the 16 filled pairs of cells, because the same ayanamsa is subtracted whether the centre is the Earth or the Sun. The ayanamsa page sets out what that value is. Changing the centre and changing the zodiac are independent choices; the draconic chart page works through a third, re-measuring every longitude from the Moon’s node.

What This Page Does Not Give

According to the Wikipedia article, heliocentric astrologers interpret mainly the aspects and configurations between planets. This page interprets nothing: no planet, sign or aspect in either chart is given a meaning for anyone, because an ephemeris can check where a planet stands as seen from the Sun and no calculation can check what that position is taken to signify. It lists no heliocentric aspects either, and it is not a calculator for a birth date.

In Brief

• Centre: a heliocentric chart places the planets as seen from the Sun’s centre; the Earth replaces the Sun and sits opposite it; houses, ascendant and midheaven drop out
• How often tropical signs differ (1950–2050): Mercury 88.5% of days, Mars 73.2%, Jupiter 25.0%, Pluto 3.6%, falling outward planet by planet
• Retrograde: none in a heliocentric chart; geocentric Pluto moves backwards on 43.6% of days
• Mercury: 49 heliocentric sign entries in 2027 against 16 geocentric, one round every 87.9 days
• 28 October 2026: 3 of 6 planets with a known heliocentric sign are in a different sign from the geocentric chart