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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

TonightSkytype

The answer to "what can I see from here, now".

Import it

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

Definition

interface TonightSky {
    sunAltitude: number;
    twilight: Twilight;
    limitingMagnitude: number;
    stars: VisibleStar[];
}

Members

NameTypeDescription
sunAltitudenumber

The Sun's altitude in degrees, geometric.

twilightTwilight

The kind of darkness that gives.

limitingMagnitudenumber

The faintest apparent magnitude seen now: the site's limit lowered by twilight and the Moon. Below -5 when it is day, so nothing but Venus and the Moon would show.

starsVisibleStar[]

The stars, brightest first (by apparent magnitude). Only the visible ones unless all was asked for.

Examples

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

const sky: TonightSky = visibleStars({ observer: { latitude: 49.28, longitude: -123.12 }, when: Date.UTC(2026, 10, 8, 6) });
console.log(sky.twilight, sky.stars.length);
night 1748

What it prints (run when this page was built)

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