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Wakusei Planets惑星

The Sun, the planets and their moons as a clean line drawing, a shaded realistic drawing or a painted surface map, with real sizes, tilt and rotation, and the moons where they are at any date and time.

Wakusei is the Japanese word 惑星 for a planet. About the name

Contents

Reference · Julian dates (and the julian package's functions), calendars, time scales, sidereal time and Mars time

deltaTfunction

Delta T, terrestrial time minus universal time (UT1), in seconds. From 1972 it is the leap seconds plus 32.184 s less dut1 (UT1 minus UTC, which the IERS publishes and is under 0.9 s: leave it out and it is taken as 0), before 1972 the polynomials of Espenak and Meeus (NASA). After the last leap second it is held at 69.184 s, the assumption JPL Horizons makes.

Import it

import { deltaT } from "@johnmorrisdotca/wakusei-planets/time";

Definition

function deltaT(when: When, dut1?: number): number

Parameters

NameTypeDescription
whenWhen

A Date or milliseconds since 1970 (UTC).

dut1 (optional)number

UT1 minus UTC in seconds, from the IERS; default 0.

Returns

number

Seconds.

Examples

import { deltaT } from "@johnmorrisdotca/wakusei-planets/time";

console.log(deltaT(Date.UTC(1900, 0, 1)).toFixed(1), deltaT(Date.UTC(2026, 10, 7)));
-2.7 69.184

What it prints (run when this page was built)

View sourceEdit on GitHubMade from the source of @johnmorrisdotca/wakusei-planets 0.24.0.