What Changes in My Birth Chart If My Birth Time Is Approximate?

Usually the Sun and the slower planets keep their signs, the Moon sometimes changes, and the rising sign and houses are the most sensitive. The explorer below shows exactly which parts of your chart stay the same across your time range and which don't, without pretending to know the precise minute.

Which parts of a chart depend on the clock

A birth chart combines two kinds of motion. The planets move slowly through the zodiac: the Sun about one degree a day, the Moon about thirteen, and the outer planets far less. The rising sign comes from Earth's daily rotation instead: the eastern horizon sweeps through all twelve signs in about a day, so the rising sign typically changes every two hours or so, faster for some signs and at high latitudes. In Whole Sign houses, which Kosmo uses, the rising sign becomes the 1st house and each following sign the next house, so every house moves with it.

What the explorer calculates: for an approximate time, your range is real elapsed minutes on each side of your estimate. Every point is checked often enough that no sign change can slip between two checks, and each change is then located to the second. For an unknown time, it checks the whole local calendar day, which lasts 23 or 25 hours on clock-change days. Your entries stay on this page and are never stored, sent or added to the address.

Exact, approximate and unknown: three honest answers

With an exact time you get one chart, plus how long your rising sign holds around that time, so you can see how much margin a recorded time has. With an approximate time, a point counts as stable only if it stays in the same sign for the entire range, not just at the two ends. With an unknown time, the rising sign and houses are usually open, while the Sun and the slow planets typically keep one sign all day.

Midnight, clock changes and repeated hours

A range can cross midnight; the explorer follows it into the next or previous date as one continuous stretch. Daylight-saving changes need more care. A time that never existed on local clocks, such as 02:30 on a spring-forward night, gets no result, because any chart for it would be invented. A time that happened twice, on a fall-back night, isn't calculated until you choose the first or the second occurrence. Whenever the clocks changed inside your range, times are shown with their UTC offset.

What the explorer will not do

It never estimates your true birth time from personality traits, life events or a sign description you prefer. That practice, called rectification, depends on interpretation, and this tool deliberately leaves it out. Keep three layers apart: the positions are exact astronomy, your time range is an estimate, and the meaning of any sign is symbolic.

• Look for a written time on your birth certificate, hospital record or baby book.
• Ask relatives whether the time was recorded or remembered, and how precisely.
• If you only know part of the day, such as the morning, enter its middle with a range of up to three hours on each side.

When you're ready, the free report on this page maps your full chart. Without a birth time, it shows the signs your planets could be in that day and leaves out the rising sign and houses. It's free, unlimited and needs no account.