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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

VisibleStartype

A star above the horizon and how it looks from there.

Import it

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

Definition

interface VisibleStar {
    star: Star;
    altitude: number;
    azimuth: number;
    airmass: number;
    apparentMagnitude: number;
    ease: Ease;
}

Members

NameTypeDescription
starStar

The catalogue star.

altitudenumber

Degrees above the horizon (geometric, no refraction).

azimuthnumber

Degrees from north through east.

airmassnumber

The airmass along the line of sight: 1 at the zenith, about 38 at the horizon.

apparentMagnitudenumber

The magnitude after the air has dimmed it: star.magnitude plus the extinction's share above the zenith's.

easeEase

How easy it is to see.

Examples

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

const first: VisibleStar | undefined = visibleStars({ observer: { latitude: 49.28, longitude: -123.12 }, when: Date.UTC(2026, 10, 8, 6) }).stars[0];
console.log(first?.star.name, first?.altitude);
Capella 47.25276501952862

What it prints (run when this page was built)

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