Know your original birthday: Astronomy and geospatial analysis-temporary Epython

They organize birthday celebrations next year three friends: Gabriel, Jacques, and Camille. All three were born in 1996, in Paris, France, so they will be 30 years later in 2026. Gabriel and Jacques will be Tokyo, Japan, during the settlement. Gabriel and Camille often celebrate their birthdays in any year in the “official” days mentioned in their birth certificates – January 18 and May 5, respectively. Jacques, born on February 29, you choose to celebrate his birthday (or Memorial Cusina) March 1 years different.

We use skip for years In order to keep our calendar against the earthquake around the sun. A The year of the sun – Time that takes the world to complete one full orbit around the sun – about 365.25 days. Through the meeting, the Gregorian Calendar offers 365 days each year, outside the age of EXEAP, receiving 366 days to compensate the dispute over time. This makes you wonder: Are there your friends who will celebrate their birthday to the coming “real” day, that is, date that is in the same situation in the sky (Related to the Land) as it was bound? Could your friends eventually celebrate 30 – Special Milestone – Day Soon or Day too late?

The following article uses the birthplace of the disciples for some open scientific PHYthon packages and are fully operational for the Aulloni's pylonical and geospatial analysis-temporarily, including skyfield, timezonefinder, geopybesides pytz. Finding a hand experience, we will use these packages to solve our happy problem with accurate predictor “real birth” (or date of return of the sun) In the year of the future. Then we will discuss how such packages can be matured in other actual health apps.

The predictor of the real birthday

Project Setup

All startup steps below are tested at Cos Sequence 15.6.1 and should be the same in Linux and Windows.

Let's first set up the project directory. We will be using uv Management of the project (see the Input Orders here). Verify the installed version in the Forum:

uv --version

Start a project guide called real-birthday-predictor At the right place on your local machine:

uv init --bare real-birthday-predictor

In the project track, create a requirements.txt File by leaning for the following:

skyfield==1.53
timezonefinder==8.0.0
geopy==2.4.1
pytz==2025.2

Here is a brief view of each package:

• skyfield It provides the activities of the stars. It can be used to include the exact heavenly positions (eg, the sun, the moon, planets, and satellites) to help determine the increase in the rise / setups and orbital. Depends on what is called Ephemes . In this article, we will use a File De421 in Phemesis, including days on July 29, 1899, on October 9, 2053.
• timezonefinder Has the Latitudes and longitudes coordinates (eg, “Europe / Paris”). It can do this an online interface.
• geopy It provides geoSpatial analysis tasks, such as getting map between local addresses and links. We will use it and the Nominatim Openstretchemap data game is calculating the map names of cities and countries to link.
• pytz It provides temporary analytics analytics and time change time. We will use the conversion between UTC and local times use the Date Saving Laws.

We will also use other few-built-in modules, such as datetime What's done and the amount of time of day / time to deceive, calendar A year testing, and time Sleeping between geocoding restoration.

Next, create visual Python Code 3.12 within the project guide, Activate the environment, and then enter the reliance:

uv venv --python=3.12 
source .venv/bin/activate
uv add -r requirements.txt

Check that leaning is included:

uv pip list

Work

At this stage, we will be in a piece of the actual “real” birth “birth and the future and the place of celebration. First, we import the required modules:

from datetime import datetime, timedelta
from skyfield.api import load, wgs84
from timezonefinder import TimezoneFinder
from geopy.geocoders import Nominatim
from geopy.exc import GeocoderTimedOut
import pytz
import calendar
import time

We are then explaining how, using different variety of different words and Doctring text:

def get_real_birthday_prediction(
    official_birthday: str,
    official_birth_time: str,
    birth_country: str,
    birth_city: str,
    current_country: str,
    current_city: str,
    target_year: str = None
):
    """
    Predicts the "real" birthday (solar return) for a given year,
    accounting for the time zone at the birth location and the time zone
    at the current location. Uses March 1 in non-leap years for the civil 
    anniversary if the official birth date is February 29.
    """

note that current_country including current_city Collectively look at a place where the birthday will be celebrated at the intended age.

We guarantee inputs before work with them:

    # Determine target year
    if target_year is None:
        target_year = datetime.now().year
    else:
        try:
            target_year = int(target_year)
        except ValueError:
            raise ValueError(f"Invalid target year '{target_year}'. Please use 'yyyy' format.")

    # Validate and parse birth date
    try:
        birth_date = datetime.strptime(official_birthday, "%d-%m-%Y")
    except ValueError:
        raise ValueError(
            f"Invalid birth date '{official_birthday}'. "
            "Please use 'dd-mm-yyyy' format with a valid calendar date."
        )

    # Validate and parse birth time
    try:
        birth_hour, birth_minute = map(int, official_birth_time.split(":"))
    except ValueError:
        raise ValueError(
            f"Invalid birth time '{official_birth_time}'. "
            "Please use 'hh:mm' 24-hour format."
        )

    if not (0 <= birth_hour <= 23):
        raise ValueError(f"Hour '{birth_hour}' is out of range (0-23).")
    if not (0 <= birth_minute <= 59):
        raise ValueError(f"Minute '{birth_minute}' is out of range (0-59).")

Next, we use geopy by Nominatim Geocoder to get a birth and present places. To avoid finding out errors from time, we place a long-term amount of time for ten-minute; This is how much is this safe_geocode Work expects geocoding cooking service to reply before raising a geopy.exc.GeocoderTimedOut outside. MORE SAFETY, WORK TRY TRYING THE PROVISION 3 TIMESDMENTS Before I quit:

    geolocator = Nominatim(user_agent="birthday_tz_lookup", timeout=10)

    # Helper function to call geocode API with retries
    def safe_geocode(query, retries=3, delay=1):
        for attempt in range(retries):
            try:
                return geolocator.geocode(query)
            except GeocoderTimedOut:
                if attempt < retries - 1:
                    time.sleep(delay)
                else:
                    raise RuntimeError(
                        f"Could not retrieve location for '{query}' after {retries} attempts. "
                        "The geocoding service may be slow or unavailable. Please try again later."
                    )
    
    birth_location = safe_geocode(f"{birth_city}, {birth_country}")
    current_location = safe_geocode(f"{current_city}, {current_country}")

    if not birth_location or not current_location:
        raise ValueError("Could not find coordinates for one of the locations. Please check spelling.")

Current birth links and present sites, points to applicable areas and UTC and date of birth. We also think that people like Jacques, born on February 29, will choose to celebrate their birthday 1 years:

    # Get time zones
    tf = TimezoneFinder()
    birth_tz_name = tf.timezone_at(lng=birth_location.longitude, lat=birth_location.latitude)
    current_tz_name = tf.timezone_at(lng=current_location.longitude, lat=current_location.latitude)

    if not birth_tz_name or not current_tz_name:
        raise ValueError("Could not determine timezone for one of the locations.")

    birth_tz = pytz.timezone(birth_tz_name)
    current_tz = pytz.timezone(current_tz_name)

    # Set civil anniversary date to March 1 for February 29 birthdays in non-leap years
    birth_month, birth_day = birth_date.month, birth_date.day
    if (birth_month, birth_day) == (2, 29):
        if not calendar.isleap(birth_date.year):
            raise ValueError(f"{birth_date.year} is not a leap year, so February 29 is invalid.")
        civil_anniversary_month, civil_anniversary_day = (
            (3, 1) if not calendar.isleap(target_year) else (2, 29)
        )
    else:
        civil_anniversary_month, civil_anniversary_day = birth_month, birth_day

    # Parse birth datetime in birth location's local time
    birth_local_dt = birth_tz.localize(datetime(
        birth_date.year, birth_month, birth_day,
        birth_hour, birth_minute
    ))
    birth_dt_utc = birth_local_dt.astimezone(pytz.utc)

Using DE421 Data Ephemisis, calculates when the sun was (ie, of it Ecliptic Longitude) In the exact time and place a birth person:

    # Load ephemeris data and get Sun's ecliptic longitude at birth
    eph = load("de421.bsp")  # Covers dates 1899-07-29 through 2053-10-09
    ts = load.timescale()
    sun = eph["sun"]
    earth = eph["earth"]
    t_birth = ts.utc(birth_dt_utc.year, birth_dt_utc.month, birth_dt_utc.day,
                     birth_dt_utc.hour, birth_dt_utc.minute, birth_dt_utc.second)
    
    # Birth longitude in tropical frame from POV of birth observer on Earth's surface
    birth_observer = earth + wgs84.latlon(birth_location.latitude, birth_location.longitude)
    ecl = birth_observer.at(t_birth).observe(sun).apparent().ecliptic_latlon(epoch='date')
    birth_longitude = ecl[1].degrees

Note that, for the first time the line eph = load("de421.bsp") murdered, de421.bsp The file will be downloaded and installed on the project identification; In all future killings, the downloaded file will be directly used. It is possible to convert code to load other Ephemisis file (eg. de440s.bspWhat is united on January 22, 2150).

Now comes the interesting part of the work: We will make the first “Defense” Day “birthday” day in the intended day, describing safe boundaries and time.

    # Initial guess for target year solar return
    approx_dt_local_birth_tz = birth_tz.localize(datetime(
        target_year, civil_anniversary_month, civil_anniversary_day,
        birth_hour, birth_minute
    ))
    approx_dt_utc = approx_dt_local_birth_tz.astimezone(pytz.utc)

    # Compute Sun longitude from POV of current observer on Earth's surface
    current_observer = earth + wgs84.latlon(current_location.latitude, current_location.longitude)

    def sun_longitude_at(dt):
        t = ts.utc(dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second)
        ecl = current_observer.at
        return ecl[1].degrees

    def angle_diff(a, b):
        return (a - b + 180) % 360 - 180

    # Set safe upper and lower bounds for search space
    dt1 = approx_dt_utc - timedelta(days=2)
    dt2 = approx_dt_utc + timedelta(days=2)

    # Use binary search with early-stopping to solve for exact solar return in UTC
    old_angle_diff = 999
    for _ in range(50):
        mid = dt1 + (dt2 - dt1) / 2
        curr_angle_diff = angle_diff(sun_longitude_at(mid), birth_longitude)
        if old_angle_diff == curr_angle_diff:  # Early-stopping condition
            break
        if curr_angle_diff > 0:
            dt2 = mid
        else:
            dt1 = mid
        old_angle_diff = curr_angle_diff

    real_dt_utc = dt1 + (dt2 - dt1) / 2

Look at this article to find many examples of using binary uses and understand why this algorithm is important for data science.

Finally, the real “day of” birth “and the Binary Search is converted to the current local time, formatted as needed, and restored:

    # Convert to current location's local time and format output
    real_dt_local_current = real_dt_utc.astimezone(current_tz)
    date_str = real_dt_local_current.strftime("%d/%m")
    time_str = real_dt_local_current.strftime("%H:%M")

    return date_str, time_str, current_tz_name

Examination

We are now in a position to predict Gabriel's dates, real, Jacques, and Jaces, and Jaces26.

Doing the work of working easier digestion, here is the help function we will use to print each question results:

def print_real_birthday(
    official_birthday: str,
    official_birth_time: str,
    birth_country: str,
    birth_city: str,
    current_country: str,
    current_city: str,
    target_year: str = None):
    """Pretty-print output while hiding verbose error traces."""

    print("Official birthday and time:", official_birthday, "at", official_birth_time)

    try:
        date_str, time_str, current_tz_name = get_real_birthday_prediction(
            official_birthday,
            official_birth_time,
            birth_country,
            birth_city,
            current_country,
            current_city,
            target_year
        )

        print(f"In year {target_year}, your real birthday is on {date_str} at {time_str} ({current_tz_name})n")

    except ValueError as e:
        print("Error:", e)

Here are the test cases:

# Gabriel
print_real_birthday(
    official_birthday="18-01-1996", 
    official_birth_time="02:30",
    birth_country="France",
    birth_city="Paris",
    current_country="France",
    current_city="Paris",
    target_year="2026"
)

# Jacques
print_real_birthday(
    official_birthday="29-02-1996", 
    official_birth_time="05:45",
    birth_country="France",
    birth_city="Paris",
    current_country="France",
    current_city="Paris",
    target_year="2026"
)

# Camille
print_real_birthday(
    official_birthday="05-05-1996", 
    official_birth_time="20:30",
    birth_country="Paris",
    birth_city="France",
    current_country="Japan",
    current_city="Tokyo",
    target_year="2026"
)

Here are the results:

Official birthday and time: 18-01-1996 at 02:30
In year 2026, your real birthday is on 17/01 at 09:21 (Europe/Paris)

Official birthday and time: 29-02-1996 at 05:45
In year 2026, your real birthday is on 28/02 at 12:37 (Europe/Paris)

Official birthday and time: 05-05-1996 at 20:30
In year 2026, your real birthday is on 06/05 at 09:48 (Asia/Tokyo)

As we see, the original “birthday” is different from the official birthday to all three of your friends: while Camille should wait for its official date in Tokyo.

As an easy way to follow the above steps, the author of this Range has created a Python library called solarius To access the same effect (see the details here). Add a library with pip install solarius or uv add solarius and use it as shown below:

from solarius.model import SolarReturnCalculator

calculator = SolarReturnCalculator(ephemeris_file="de421.bsp")

# Predict without printing
date_str, time_str, tz_name = calculator.predict(
    official_birthday="18-01-1996",
    official_birth_time="02:30",
    birth_country="France",
    birth_city="Paris",
    current_country="France",
    current_city="Paris",
    target_year="2026"
)

print(date_str, time_str, tz_name)

# Or use the convenience printer
calculator.print_real_birthday(
    official_birthday="18-01-1996",
    official_birth_time="02:30",
    birth_country="France",
    birth_city="Paris",
    current_country="France",
    current_city="Paris",
    target_year="2026"
)

Of course, there is much to birth rather than forecasting ecosystems – these special days are full of centuries. Here is a short video on the interesting origin of birthdays:

More than the birthdays

The purpose of the above section was to give students a case of exciting and accurate use of various astronomical packages and geoSpatial-temporbers analysis. However, the usefulness of such packages go on somewhat to predict birthdays.

For example, all the packages can be used for some astrological conditions (eg determines when sunrise, sunset, or sun cuts will take place on a given place). To predict the satellites movements and other weather bodies can play a vital part in organizing the local trip.

Packages can also be used to increase the shipment of solar panels in a particular area, such as finding a place to live or commercial area. The purpose can be predicting how much sunlight is crossing in the area different times of the year and uses this information to configure the placement, tilt, and the use of solar schedules to be taken for solar energy.

Finally, packages can be included in the construction of historical historical development (eg. The purpose here can be recycling weather conditions for a particular day and place to help researchers understand the lighting and appearing at that time.

Finally, by combining these open source packages and built-in modules in different ways, it is possible to solve exciting problems for cutting down many backgrounds.