# Moontool

[![license: 0BSD](https://img.shields.io/badge/license-0BSD-blue)](https://opensource.org/license/0BSD)
[![crates.io](https://img.shields.io/crates/d/moontool?logo=rust&logoColor=white&color=orange)](https://crates.io/crates/moontool)

John Walker's moontool.c astronomical calculation routines, extracted
and ported to Rust.

## Original

The original versions, [moontool](https://www.fourmilab.ch/moontool/)
and [moontoolw](https://www.fourmilab.ch/moontoolw/), are available at
John Walker's [fourmilab.ch](https://www.fourmilab.ch/).

Backup copies are included in the [`original/`](../../original)
directory of this repository.

## License

Walker's program is in the public domain, and so is this project.

In Walker's words:

> Do what thou wilt shall be the whole of the law.

## CLI

This version includes functions that compute info about the Moon, in a
way similar to the original program.

The CLI wraps these functions.

```
$ moontool 1994-12-22T13:53:34

Phase
=====

Julian date:            2449709.07887   (0h variant: 2449709.57887)
Universal time:         Thursday  13:53:34 22 December 1994
Local time:             Thursday  14:53:34 22 December 1994

Age of moon:            18 days, 22 hours, 29 minutes.
Lunation:               64.13%   (🌖 Waning Gibbous)
Moon phase:             81.56%   (0% = New, 100% = Full)

Moon's distance:        386212 kilometres, 60.6 Earth radii.
Moon subtends:          0.5157 degrees.

Sun's distance:         147151251 kilometres, 0.984 astronomical units.
Sun subtends:           0.5420 degrees.

Moon Calendar
=============

Last new moon:          Friday    23:54 UTC  2 December 1994    Lunation: 890
First quarter:          Friday    21:06 UTC  9 December 1994
Full moon:              Sunday     2:18 UTC 18 December 1994
Last quarter:           Sunday    19:07 UTC 25 December 1994
Next new moon:          Sunday    10:56 UTC  1 January 1995     Lunation: 891
```

## Installation

```shell
# CLI, either of:
cargo install moontool
cargo install --git https://github.com/qrichert/moontool.git

# Library
cargo add moontool
```

This sets up both the CLI:

```console
$ moontool --help
```

And the library:

```rust
use moontool::moon::MoonPhase;

let phase = MoonPhase::now();
```

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