Visualise the sun azimuth during the eclipse

gistfile1.txt

from pysolar.solar import get_azimuth, get_altitude
import datetime
import json
import math
from datetime import timedelta
from zoneinfo import ZoneInfo

LAT = 51.5649288
LON = 0.0172429

ZONE_INFO = ZoneInfo("Europe/London")
ECL_START = datetime.datetime(2026, 8, 12, 18, tzinfo=ZONE_INFO)
ECL_END = datetime.datetime(2026, 8, 12, 21, tzinfo=ZONE_INFO)
STEP = timedelta(minutes=5)

LINE_LENGTH_METRES = 100.0
OUTPUT_PATH = "sun_position.geojson"

METRES_PER_DEGREE_LATITUDE = 111_320.0


def destination_point(lat, lon, azimuth_degrees, distance_metres):
    """Point at the given distance and bearing from (lat, lon).

    Uses a flat-earth approximation, which is accurate to well under
    a metre at the distances these lines span.
    """
    azimuth_radians = math.radians(azimuth_degrees)
    delta_lat = distance_metres * math.cos(azimuth_radians) / METRES_PER_DEGREE_LATITUDE
    delta_lon = (
        distance_metres
        * math.sin(azimuth_radians)
        / (METRES_PER_DEGREE_LATITUDE * math.cos(math.radians(lat)))
    )
    return lat + delta_lat, lon + delta_lon


def time_range(start, end, step):
    current = start
    while current <= end:
        yield current
        current += step


features = []
for steptime in time_range(ECL_START, ECL_END, STEP):
    azimuth = get_azimuth(LAT, LON, steptime)
    elevation = get_altitude(LAT, LON, steptime)
    print(f"time={steptime} azimuth={azimuth} elevation={elevation}")

    if elevation <= 0:
        continue

    end_lat, end_lon = destination_point(LAT, LON, azimuth, LINE_LENGTH_METRES)
    features.append(
        {
            "type": "Feature",
            "geometry": {
                "type": "LineString",
                "coordinates": [[LON, LAT], [end_lon, end_lat]],
            },
            "properties": {
                "time": steptime.isoformat(),
                "azimuth": azimuth,
                "elevation": elevation,
            },
        }
    )

with open(OUTPUT_PATH, "w") as output_file:
    json.dump(
        {"type": "FeatureCollection", "features": features}, output_file, indent=2
    )

print(f"Wrote {len(features)} features to {OUTPUT_PATH}")