Al-Battani
He made significant improvements to Ptolemy's astronomical tables and accurately determined the length of the tropical year.
Most quoted
"Our fleeting existence on Earth is but a moment compared to the eternal cycles of the cosmos. Yet, in this brief span, we are granted the capacity to observe and understand."
— from Kitāb az-Zīj as-Sābi'
"The beauty of the night sky, with its countless luminaries, is a testament to the artistry of the divine, an invitation to contemplation and wonder."
— from Kitāb az-Zīj as-Sābi'
"The celestial spheres, in their intricate dance, reveal the order and majesty of the Creator. To study them is to glimpse the divine mind at work."
— from Kitāb az-Zīj as-Sābi'
All quotes by Al-Battani (382)
The science of the stars is a door to the knowledge of the Creator’s wisdom and power.
I have striven in this work for precision, knowing that a small error in the beginning leads to a great error in the end.
The equation of time is the difference between the apparent solar time and the mean solar time.
The declination of a star is its angular distance north or south of the celestial equator.
The right ascension of a star is its angular distance measured eastward along the celestial equator from the vernal equinox.
The celestial sphere rotates from east to west, carrying the stars in their diurnal motion.
The ecliptic is the great circle on the celestial sphere that the sun appears to trace over the course of a year.
The obliquity of the ecliptic I found to be approximately 23 degrees and 35 minutes.
The seasons are caused by the inclination of the earth’s axis and the sun’s motion along the ecliptic.
The length of daylight varies with the sun’s declination and the observer’s latitude.
The azimuth of a celestial body is its angular distance along the horizon from the north point.
The altitude of a body is its angular height above the horizon.
The meridian is the great circle passing through the celestial poles and the zenith of the observer.
The culmination of a star is its passage across the observer’s meridian.
The knowledge of spherical trigonometry is essential for solving astronomical problems.
I have used the sine theorem to compute arcs and angles on the celestial sphere.
The motion of the planets in latitude is governed by the inclination of their orbits to the ecliptic.
The nodes of the moon’s orbit regress along the ecliptic, completing a revolution in about 18.6 years.
The solar and lunar theories are the foundation upon which the entire science of astronomy is built.
The fixed stars retain their relative positions, but their longitudes increase uniformly due to precession.