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Hello everyone,

At the equator, celestial bodies—stars, planets, the Sun, and the Moon—rise almost vertically. However, their azimuth at rise depends on their declination at that specific date and time.

• Objects with northern declination rise toward the northeast, with a rising azimuth of approximately 90° minus their declination.
• Objects with southern declination rise toward the southeast, with a rising azimuth of approximately 90° plus their declination.

As they move across the sky during the day, these bodies trace an arc. At transit—the moment they cross the local meridian—they reach their maximum altitude, which is roughly 90° minus their declination. Depending on the declination, they will transit either due north or due south of the Equator.

At sunset, the pattern reverses: celestial bodies set toward the northwest or southwest, again depending on their declination. While a star’s declination remains constant throughout the day, the Moon’s declination can vary by up to 3° between moonrise and moonset.

Last year, during the March equinox, I had the privilege of standing directly on the Equator line near Nairobi, Kenya. I witnessed the Sun rise almost exactly due east, ascend vertically to nearly 90° altitude at transit, and set nearly due west. I say “virtually” east and west because the equinox had occurred a few hours earlier over Western Australia, so by the time the Sun reached the local meridian in Kenya, it already had a slight northern declination.

Thanks,
Martin Caminos