StarTarot research
Computed answers to astrology questions
Short studies with original numbers: each one states its method, ships the script that produced every figure and releases the data under CC BY 4.0, so you can cite it, check it or rerun it.
14 September 2026
How often the MC falls in the whole-sign 10th house, by latitude and rising sign
Computed shares of charts with the Midheaven in the whole-sign 10th house at latitudes 0–65°, tropical and sidereal, by rising sign, plus a proof that Porphyry charts have intercepted signs exactly when the MC leaves the 10th sign. Data as CSV, CC BY 4.0.
16 September 2026
How common is each rising sign, by latitude
Computed shares of every rising sign (Ascendant sign) at latitudes 0–65°, tropical and sidereal (Lahiri), with rising times, the rarest and commonest sign at each latitude, the southern-hemisphere mirror rule and a measured bound on what birth-hour clustering can change. Data as CSV, CC BY 4.0.
26 September 2026
How often each planet is retrograde, 1900–2100
All 3,660 stations of Mercury through Pluto from 1900 to 2100, computed with Swiss Ephemeris and confirmed with NASA JPL DE440: the share of time each planet is retrograde, how many are retrograde at once, the longest stretch with none, Mercury retrograde dates, and every retrograde period as CSV, CC BY 4.0.
27 September 2026
How hospital birth times reshape the birth chart: 95.7 million births in Brazil, Japan and the USA
Every recorded birth in Brazil (2006–2024), Japan (2015–2024) and the USA (2016–2024): how often the Sun is above the horizon, the Sun’s house, Sun–Ascendant pairs and Mars in the Gauquelin sectors, against astronomy and the real calendar. Data as CSV, CC BY 4.0.
17 October 2026
What is the rarest zodiac sign? Sun signs of 710 million births in 55 countries
Births recorded by day or month in 55 countries, 1960–2024 (years vary by country): the share of each Sun sign, tropical and sidereal, by country and decade, with the length of each sign, the season of births and the holidays told apart. Data as CSV, CC BY 4.0.
28 October 2026
The zodiac sign of champions is Aquarius, Libra or Taurus: 730,728 athletes, and the rulebook that decides
Exact birthdays of 730,728 athletes in 25 sports from Wikidata (born 1950–2007) against official births by month: which Sun signs are over-represented in each sport and country, why the answer follows youth-sport cutoff dates, and 56 predictions written down before the count. Data as CSV, CC BY 4.0.
Where a country’s own data support it, a study is also published in its language: Mapa diurno ou noturno? O céu de 53,6 milhões de nascimentos no Brasil (2006–2024) (Portuguese), Можно ли жениться в високосный год? 36,2 млн свадеб в России, 1990–2023 (Russian), Anno bisesto, anno funesto? 19,1 milioni di matrimoni in Italia, 1960–2024 (Italian), Stimmen die Bauernregeln? Wetterdaten von 1.282 DWD-Stationen, 1760–2025 (German), Ślub w miesiącu z „r”? 4,6 mln ślubów w Polsce dzień po dniu, 2002–2025 (Polish).
Related tools: natal chart calculator and the open tarot dataset.