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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 · The sky seen from another star: positions, distances and brightness from there, with the Sun among the stars

SeenStartype

One star as seen from a viewpoint: where it is in that sky, how far, and how bright.

Import it

import type { SeenStar } from "@johnmorrisdotca/hoshi-stars/sky-from";

Definition

interface SeenStar {
    id: string;
    name: string | undefined;
    designation: string | undefined;
    rightAscension: number;
    declination: number;
    lightYears: number;
    parsecs: number;
    magnitude: number;
    absoluteMagnitude: number;
    colourIndex: number | undefined;
    star: Star | NearbyStar | undefined;
}

Members

NameTypeDescription
idstring

A key that stays the same: hr-2491 for a bright star, gctp-3278 for a nearby star, sun for the Sun.

namestring | undefined

The common name, Sun for the Sun, else undefined.

designationstring | undefined

The Bayer letter or Flamsteed number and constellation (α CMa) where there is one, else undefined.

rightAscensionnumber

Right ascension in degrees seen from the viewpoint, 0 up to 360, on the same J2000 equatorial axes as the Earth's sky.

declinationnumber

Declination in degrees seen from the viewpoint, -90 to 90.

lightYearsnumber

The distance from the viewpoint in light-years.

parsecsnumber

The same distance in parsecs.

magnitudenumber

The apparent visual magnitude from the viewpoint: smaller is brighter. It is the absolute magnitude plus 5 log10(distance / 10 parsecs).

absoluteMagnitudenumber

The visual magnitude the star would have at 10 parsecs, worked out from its magnitude and distance from the Sun.

colourIndexnumber | undefined

The colour index B-V, or undefined where the catalogue has none. Colour does not change with distance.

starStar | NearbyStar | undefined

The catalogue's star, or undefined for the Sun. Its position, magnitude and distance are the view from the Sun; the ones above are from the viewpoint.

Examples

import { skyFrom, type SeenStar } from "@johnmorrisdotca/hoshi-stars/sky-from";

const sun: SeenStar = skyFrom("Rigil Kentaurus").find((star) => star.id === "sun")!;
console.log(sun.magnitude.toFixed(2));
0.45

What it prints (run when this page was built)

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