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Hoshi Stars星

The stars you can see without a telescope, with names, colours and distances; the 88 constellations with their lines and boundaries; the Messier objects; and seven map projections to draw them on.

Hoshi is the Japanese word 星 for a star. About the name

Contents

Reference · What you can see tonight: the stars above the horizon of a place and a moment that the Sun's light, the sky's darkness and the air still let through, with the twilight, each star's altitude and azimuth and how easy it is to see

visibleStarsfunction

The stars you can see from a place at a moment: above the horizon (or minAltitude), with the Sun low enough, and brighter than the sky's limit once the air has dimmed them (airmass, 0.2 magnitude an airmass above the zenith's one). Each star carries its altitude, azimuth, airmass, apparent magnitude and how easy it is to see; the list is brightest first. The star's proper motion is added. Accurate to a few arc-minutes in position; the limit is an approximation (see the guide), good for "will I see Orion", not for the faintest star at the threshold. No clock is read: the moment is passed in.

Import it

import { visibleStars } from "@johnmorrisdotca/hoshi-stars/tonight";

Definition

function visibleStars(query: { observer: Observer; when: When; sky?: TonightOptions; }): TonightSky

Parameters

NameTypeDescription
query{ observer: Observer; when: When; sky?: TonightOptions; }

observer (latitude north, longitude east, degrees), when (a Date or milliseconds since 1970) and sky (TonightOptions, all optional).

Returns

TonightSky

The Sun's altitude, the twilight, the limiting magnitude and the stars.

Examples

import { visibleStars } from "@johnmorrisdotca/hoshi-stars/tonight";

const vancouver = { latitude: 49.28, longitude: -123.12 };
const sky = visibleStars({ observer: vancouver, when: new Date("2026-11-08T08:00:00Z"), sky: { limit: "suburb" } });
console.log(sky.twilight, sky.stars[0]?.star.name); // night Sirius
night Sirius

What it prints (run when this page was built)

View sourceEdit on GitHubMade from the source of @johnmorrisdotca/hoshi-stars 0.47.0.