Astronoby
Ruby library to provide a useful API to compute astronomical calculations, based on astrometry books.
The main reference is:
- Astronomical Algorithms by Jean Meeus
- Celestial Calculations by J. L. Lawrence
- Practical Astronomy with your Calculator or Spreadsheet by Peter Duffet-Smith and Jonathan Zwart
Content
Installation
Install the gem and add to the application's Gemfile by executing:
$ bundle add astronoby
If bundler is not being used to manage dependencies, install the gem by executing:
$ gem install astronoby
Usage
This library is still in heavy development. The public is not stable, please be aware new minor versions will probably lead to breaking changes until a major one is released.
Angle manipulation
angle1 = Astronoby::Angle.from_degrees(90)
angle2 = Astronoby::Angle.from_radians(Math::PI / 2)
angle3 = Astronoby::Angle.from_hours(12)
angle1 == angle2
# => true
angle1 < angle3
# => true
angle = angle1 + angle2 + angle3
angle.cos
# => 1.0
Distance manipulation
distance1 = Astronoby::Distance.from_astronomical_units(1)
distance2 = Astronoby::Distance.from_kilometers(149_597_870.7)
distance3 = Astronoby::Distance.from_meters(300)
distance1 == distance2
# => true
distance1 > distance3
# => true
distance =
Astronoby::Distance.from_m(300) +
Astronoby::Distance.from_km(3)
distance.km
# => 3.3
Coordinates conversion
observer = Astronoby::Observer.new(
latitude: Astronoby::Angle.from_degrees(38),
longitude: Astronoby::Angle.from_degrees(-78)
)
equatorial = Astronoby::Coordinates::Equatorial.new(
right_ascension: Astronoby::Angle.from_hms(17, 43, 54),
declination: Astronoby::Angle.from_dms(-22, 10, 0)
)
horizontal = equatorial.to_horizontal(
time: Time.new(2016, 1, 21, 21, 30, 0, "-05:00"),
observer: observer
)
horizontal.altitude.str(:dms)
# => "-73° 27′ 19.1557″"
horizontal.azimuth.str(:dms)
# => "+341° 33′ 21.587″"
Sun
Sun's location in the sky
time = Time.utc(2023, 2, 17, 11, 0, 0)
observer = Astronoby::Observer.new(
latitude: Astronoby::Angle.from_degrees(48.8566),
longitude: Astronoby::Angle.from_degrees(2.3522)
)
sun = Astronoby::Sun.new(time: time)
horizontal_coordinates = sun.horizontal_coordinates(
observer: observer
)
horizontal_coordinates.altitude.degrees
# => 27.500082409271247
horizontal_coordinates.altitude.str(:dms)
# => "+27° 30′ 0.2966″"
Sunrise and sunset times and azimuths
time = Time.new(2015, 2, 5)
observer = Astronoby::Observer.new(
latitude: Astronoby::Angle.from_degrees(38),
longitude: Astronoby::Angle.from_degrees(-78)
)
sun = Astronoby::Sun.new(time: time)
observation_events = sun.observation_events(observer: observer)
observation_events.rising_time
# => 2015-02-05 12:12:59 UTC
observation_events.rising_azimuth.str(:dms)
# => "+109° 29′ 34.3674″"
observation_events.transit_time
# => 2015-02-05 17:25:59 UTC
observation_events.transit_altitude.str(:dms)
# => "+36° 8′ 15.8197″"
observation_events.setting_time
# => 2015-02-05 22:39:27 UTC
observation_events.setting_azimuth.str(:dms)
# => "+250° 40′ 42.8609″"
Twilight times
time = Time.new(2024, 1, 1)
sun = Astronoby::Sun.new(time: time)
observer = Astronoby::Observer.new(
latitude: Astronoby::Angle.from_degrees(48.8566),
longitude: Astronoby::Angle.from_degrees(2.3522)
)
twilight_events = sun.twilight_events(observer: observer)
twilight_events.morning_astronomical_twilight_time
# => 2024-01-01 05:49:25 UTC
twilight_events.morning_nautical_twilight_time
# => 2024-01-01 06:27:42 UTC
twilight_events.morning_civil_twilight_time
# => 2024-01-01 07:07:50 UTC
twilight_events.evening_civil_twilight_time
# => 2024-01-01 16:40:01 UTC
twilight_events.evening_nautical_twilight_time
# => 2024-01-01 17:20:10 UTC
twilight_events.evening_astronomical_twilight_time
# => 2024-01-01 17:58:26 UTC
Solstice and Equinox times
year = 2024
Astronoby::EquinoxSolstice.march_equinox(year)
# => 2024-03-20 03:05:08 UTC
Astronoby::EquinoxSolstice.june_solstice(year)
# => 2024-06-20 20:50:18 UTC
Moon
Moon's location in the sky
time = Time.utc(2023, 2, 17, 11, 0, 0)
observer = Astronoby::Observer.new(
latitude: Astronoby::Angle.from_degrees(48.8566),
longitude: Astronoby::Angle.from_degrees(2.3522)
)
moon = Astronoby::Moon.new(time: time)
horizontal_coordinates = moon.horizontal_coordinates(
observer: observer
)
horizontal_coordinates.altitude.degrees
# => 10.277834691708053
horizontal_coordinates.altitude.str(:dms)
# => "+10° 16′ 40.2048″"
Moon's current attributes
time = Time.utc(2024, 6, 1, 10, 0, 0)
moon = Astronoby::Moon.new(time: time)
moon.illuminated_fraction.round(2)
# => 0.31
moon.distance.km.round
# => 368409
moon.phase_angle.degrees.round
# => 112
Moon's phases of the month
june_phases = Astronoby::Moon.monthly_phase_events(
year: 2024,
month: 6
)
june_phases.each { puts "#{_1.phase}: #{_1.time}" }
# new_moon: 2024-06-06 12:37:41 UTC
# first_quarter: 2024-06-14 05:18:28 UTC
# full_moon: 2024-06-22 01:07:53 UTC
# last_quarter: 2024-06-28 21:53:25 UTC
Moonrise and moonset times and azimuths
time = Time.utc(2024, 6, 1, 10, 0, 0)
observer = Astronoby::Observer.new(
latitude: Astronoby::Angle.from_degrees(48.8566),
longitude: Astronoby::Angle.from_degrees(2.3522)
)
moon = Astronoby::Moon.new(time: time)
observation_events = moon.observation_events(observer: observer)
observation_events.rising_time
# => 2024-06-01 00:35:36 UTC
observation_events.rising_azimuth.str(:dms)
# => "+93° 7′ 43.2347″"
observation_events.transit_time
# => 2024-06-01 02:42:43 UTC
observation_events.transit_altitude.str(:dms)
# => "+26° 59′ 30.9915″"
observation_events.setting_time
# => 2024-06-01 16:02:26 UTC
observation_events.setting_azimuth.str(:dms)
# => "+273° 29′ 30.0954″"
Precision
The current precision for the Sun's apparent location in the sky, compared to values computed by the IMCCE is approximately 1 arc minute. It corresponds to twice the apparent size of Jupiter when it is the closest to Earth.
While the precision is not enough for very high accuracy computations, it is equal to the Human naked eye's angular resolution.
Development
After checking out the repo, run bin/setup to install dependencies. Then, run
rake spec to run the tests. You can also run bin/console for an interactive
prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install. To
release a new version, update the version number in version.rb, and then run
bundle exec rake release, which will create a git tag for the version, push
git commits and the created tag, and push the .gem file to rubygems.org.
Contributing
Please see CONTRIBUTING.md.
License
The gem is available as open source under the terms of the MIT License.
Code of Conduct
Everyone interacting in the Astronoby project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.