Cool Moon Facts by Whip

Real astronomy and dated history, with sources. Documented traditions and folklore. Modern lunar astrology · symbolic, not predictive.

Chart basics · Houses · Beginner

Cusp

The boundary line where a house begins; loosely, the edge between two signs.

In a chart, the cusp of a house is the zodiac degree where that house starts. The cusps of the first, fourth, seventh and tenth houses coincide with the angles in quadrant systems such as Placidus. In everyday talk, being “born on the cusp” means being born near the day the Sun changes sign, but the Sun is always in one sign or the other at any instant.

How it is worked out
On this site, a body exactly on a cusp belongs to the house that the cusp begins.
  • Kind: Calculation
  • Tradition: Shared across Western traditions
  • In this site’s birth chart: used

Related: House, House system, Born on the cusp, Angles

Written for Cool Moon Facts in its own words. An astrology source documents what astrologers believe or practise; it does not establish that astrology works.

All terms · Your birth chart

Settings

Your location

Only used to work out rise and set times. It stays in this browser.

Moon orientation

Southern-hemisphere skies show the moon flipped. This follows your location automatically.

Saved facts

Everything saved here

This site keeps your location, your saved facts and your settings in this browser and nowhere else. Nothing is uploaded, and nothing here can be recovered once it is gone.

Cool Moon Facts · built by Whiptronics LLC

Gear that makes it better

Where these numbers come from