Asteroids in Astrology
Asteroids are small rocky bodies that orbit the Sun. Most of them lie in the main belt between Mars and Jupiter. Giuseppe Piazzi found the first, Ceres, on 1 January 1801. Pallas (1802), Juno (1804) and Vesta (1807) followed. Since 2006 Ceres has been classed as a dwarf planet.
These four came late to astrology because there was no reliable ephemeris. Eleanor Bach's asteroid ephemeris of 1973 and Demetra George's Asteroid Goddesses of 1986 brought them into modern natal work. The classical tradition has no place for asteroids: rulership, exaltation and the other dignities belong to the seven planets alone. Asteroids are a modern layer of interpretation added to the chart. The article Lilith, Asteroids, and Hypothetical Points looks at them from the classical side. The myths of the four goddesses and of other asteroids are on the Asteroid Mythology pages.
Charles Kowal discovered Chiron in 1977. It is a centaur orbiting between Saturn and Uranus, and it carries both an asteroid number (2060 Chiron) and a comet name (95P/Chiron). Astrologers usually read it together with the asteroids, which is why it is in the default list.
How asteroids are numbered
Once its orbit is known well enough, an asteroid receives a permanent number from the Minor Planet Center, which works under the International Astronomical Union. The number follows the order in which orbits were secured, not the date of discovery: 1 Ceres, 2 Pallas, 3 Juno, 4 Vesta. The name is usually proposed by the discoverer and approved by the relevant IAU working group.
Every named asteroid has a number, but not every numbered asteroid has a name. Numbered asteroids now run into the hundreds of thousands, and more are added every month. Unnamed ones go by their discovery designation. 1977 UB, for example, is Chiron's. Any numbered asteroid can be calculated here. If it has no name, it is added by its number.
Data source: NASA JPL
Name and number searches use JPL's Small-Body Database, and positions come from the JPL Horizons system. Horizons integrates each asteroid's orbit numerically together with the pull of the planets. The tool takes the geocentric apparent position for the moment of birth: light travel time and the shift caused by the Earth's own motion are included, and the longitude is given for the equinox of date, that is, in the tropical zodiac.
Compared with the Swiss Ephemeris for ten asteroids (Ceres, Pallas, Juno, Vesta, Chiron, Eros, Psyche, Lilith, Sappho, Hygiea), the difference stayed below 3 arcseconds. For faint, distant bodies with few observations, JPL's current orbit is more reliable than older ephemeris files. If JPL cannot be reached at that moment, the site's own ephemeris is used for Ceres, Pallas, Juno, Vesta and Chiron (1900 to 2099), and the table says so.
Asteroid Lilith is not Black Moon Lilith
1181 Lilith is a real asteroid discovered in 1927. Black Moon Lilith is the point of the Moon's orbit farthest from the Earth and is not a physical body. This tool calculates the asteroid only.
Reading the results
The table gives each asteroid's sign and degree, whether it is direct or retrograde, and its house when the birth time is known. The contacts list shows the aspects the asteroids make to your natal planets and angles, starting with the tightest orb. An applying aspect is not yet exact, a separating one has already passed exactness. On the wheel the asteroids appear by short name in the outer ring and as small gold dots in the inner circle.