Attention deficit hyperactivity disorder (ADHD) should be diagnosed and treated in children as young as age 4, according to new guidelines from the American Academy of Pediatrics. Skip to main content
ephemeris. 1  a table showing the positions of a heavenly body on a number of dates in a regular sequence. 2  an astronomical almanac containing such tables. 3  Archaic. an almanac or calendar.
When software is used that does not contain an ephemeris, or if no software is used, position data for celestial objects may be obtained from the modern Nautical Almanac or Air Almanac. An ephemeris is usually only correct for a particular location on the Earth. In many cases, the differences are too small to matter.